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SheetJS 2023-10-16 05:12:56 -04:00
parent 009d4e0a21
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---
title: Bun
pagination_prev: getting-started/index
pagination_next: getting-started/examples/index
sidebar_position: 7
@ -9,8 +10,6 @@ sidebar_custom_props:
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
# Bun
Tarballs are available on <https://cdn.sheetjs.com>.
<p><a href={`https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz`}>https://cdn.sheetjs.com/xlsx-{current}/xlsx-{current}.tgz</a> is the URL for version {current}</p>
@ -85,5 +84,5 @@ import * as cpexcel from 'xlsx/dist/cpexcel.full.mjs';
XLSX.set_cptable(cpexcel);
```
[^1]: Bun releases before the official 1.0.0 release did not support tarball dependencies. If a pre-1.0.0 release must be used, the module can be installed with a package manager like Yarn or the ESM script can be vendored.
[^1]: Bun releases before the official 1.0.0 release did not support tarball dependencies. If a pre-1.0.0 release must be used, the [ES Module script can be vendored](/docs/getting-started/installation/standalone#ecmascript-module-imports) or the [NodeJS module can be installed with a NodeJS-compatible package manager](/docs/getting-started/installation/nodejs).
[^2]: See [the relevant issue in the Bun issue tracker](https://github.com/oven-sh/bun/issues/101)

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---
title: HTTP Network Requests
pagination_next: demos/net/server/index
---
<head>

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---
title: HTTP Server Processing
---
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
Server-Side JS platforms like NodeJS and Deno have built-in APIs for listening
on network interfaces. They provide wrappers for requests and responses.
## Overview
#### Reading Data
Typically servers receive form data with content type `multipart/form-data` or
`application/x-www-form-urlencoded`. The platforms themselves typically do not
provide "body parsing" functions, instead leaning on the community to supply
modules to take the encoded data and split into form fields and files.
NodeJS servers typically use a parser like `formidable`. In the example below,
`formidable` will write to file and `XLSX.readFile` will read the file:
```js
var XLSX = require("xlsx"); // This is using the CommonJS build
var formidable = require("formidable");
require("http").createServer(function(req, res) {
if(req.method !== "POST") return res.end("");
/* parse body and implement logic in callback */
// highlight-next-line
(new formidable.IncomingForm()).parse(req, function(err, fields, files) {
/* if successful, files is an object whose keys are param names */
// highlight-next-line
var file = files["upload"]; // <input type="file" id="upload" name="upload">
/* file.path is a location in the filesystem, usually in a temp folder */
// highlight-next-line
var wb = XLSX.readFile(file.filepath);
// print the first worksheet back as a CSV
res.end(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
}).listen(process.env.PORT || 3000);
```
`XLSX.read` will accept NodeJS buffers as well as `Uint8Array`, Base64 strings,
binary strings, and plain Arrays of bytes. This covers the interface types of
a wide variety of frameworks.
#### Writing Data
Typically server libraries use a response API that accepts `Uint8Array` data.
`XLSX.write` with the option `type: "buffer"` will generate data. To force the
response to be treated as an attachment, set the `Content-Disposition` header:
```js
var XLSX = require("xlsx"); // This is using the CommonJS build
require("http").createServer(function(req, res) {
if(req.method !== "GET") return res.end("");
var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
// highlight-start
res.setHeader('Content-Disposition', 'attachment; filename="SheetJS.xlsx"');
res.end(XLSX.write(wb, {type:"buffer", bookType: "xlsx"}));
// highlight-end
}).listen(process.env.PORT || 3000);
```
## NodeJS
When processing small files, the work is best handled in the server response
handler function. This approach is used in the "Framework Demos" section.
When processing large files, the direct approach will freeze the server. NodeJS
provides ["Worker Threads"](#worker-threads) for this exact use case.
### Framework Demos
#### Express
:::note
This demo was verified on 2023 August 27 using `express-formidable@1.2.0` and
ExpressJS `4.18.2`
:::
The `express-formidable` middleware is powered by the `formidable` parser. It
adds a `files` property to the request.
When downloading binary data, Express handles `Buffer` data in `res.end`. The
convenience `attachment` method adds the required header:
```js
// Header 'Content-Disposition: attachment; filename="SheetJS.xlsx"'
res.attachment("SheetJS.xlsx");
```
The following demo Express server will respond to POST requests to `/upload`
with a CSV output of the first sheet. It will also respond to GET requests to
`/download`, responding with a fixed XLSX worksheet:
```js title="SheetJSExpressCSV.js"
var XLSX = require('xlsx'), express = require('express');
/* create app */
var app = express();
/* add express-formidable middleware */
// highlight-next-line
app.use(require('express-formidable')());
/* route for handling uploaded data */
app.post('/upload', function(req, res) {
// highlight-start
var f = req.files["upload"]; // <input type="file" id="upload" name="upload">
var wb = XLSX.readFile(f.path);
// highlight-end
/* respond with CSV data from the first sheet */
res.status(200).end(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
app.get('/download', function(req, res) {
/* generate workbook object */
var ws = XLSX.utils.aoa_to_sheet(["SheetJS".split(""), [5,4,3,3,7,9,5]]);
var wb = XLSX.utils.book_new(); XLSX.utils.book_append_sheet(wb, ws, "Data");
// highlight-start
/* generate buffer */
var buf = XLSX.write(wb, {type: "buffer", bookType: "xlsx"});
/* set headers */
res.attachment("SheetJSExpress.xlsx");
/* respond with file data */
res.status(200).end(buf);
// highlight-end
});
app.listen(+process.env.PORT||3000);
```
<details><summary><b>Testing</b> (click to show)</summary>
0) Save the code sample to `SheetJSExpressCSV.js`
1) Install dependencies:
<CodeBlock language="bash">{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz express@4.18.2 express-formidable@1.2.0`}
</CodeBlock>
2) Start server (note: it will not print anything to console when running)
```bash
node SheetJSExpressCSV.js
```
3) Test POST requests using <https://sheetjs.com/pres.numbers>:
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:3000/upload
```
The response should show the data in CSV rows.
4) Test GET requests by opening `http://localhost:3000/download` in your browser.
It should prompt to download `SheetJSExpress.xlsx`
</details>
#### NestJS
:::note
This demo was verified on 2023 August 27 using NestJS `10.2.0` and Multer.
:::
[The NestJS docs](https://docs.nestjs.com/techniques/file-upload) have detailed
instructions for file upload support. In the controller, the `path` property
works with `XLSX.readFile`.
When downloading binary data, NestJS expects `StreamableFile`-wrapped Buffers.
The following demo NestJS Controller will respond to POST requests to `/upload`
with a CSV output of the first sheet. It will also respond to GET requests to
`/download`, responding with a fixed export:
```ts title="src/sheetjs/sheetjs.controller.js"
import { Controller, Get, Header, Post, StreamableFile, UploadedFile, UseInterceptors } from '@nestjs/common';
import { FileInterceptor } from '@nestjs/platform-express';
import { readFile, utils, write } from 'xlsx';
@Controller('sheetjs')
export class SheetjsController {
@Post('upload') // <input type="file" id="upload" name="upload">
@UseInterceptors(FileInterceptor('upload'))
async uploadXlsxFile(@UploadedFile() file: Express.Multer.File) {
/* file.path is a path to the workbook */
// highlight-next-line
const wb = readFile(file.path);
/* generate CSV of first worksheet */
return utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]);
}
@Get('download')
@Header('Content-Disposition', 'attachment; filename="SheetJSNest.xlsx"')
async downloadXlsxFile(): Promise<StreamableFile> {
var ws = utils.aoa_to_sheet(["SheetJS".split(""), [5,4,3,3,7,9,5]]);
var wb = utils.book_new(); utils.book_append_sheet(wb, ws, "Data");
// highlight-start
/* generate buffer */
var buf = write(wb, {type: "buffer", bookType: "xlsx"});
/* Return a streamable file */
return new StreamableFile(buf);
// highlight-end
}
}
```
<details><summary><b>Testing</b> (click to show)</summary>
1) Create a new project:
<CodeBlock language="bash">{`\
npx @nestjs/cli new -p npm sheetjs-nest
cd sheetjs-nest
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz
npm i --save-dev @types/multer
mkdir -p upload`}
</CodeBlock>
2) Create a new controller and a new module:
```bash
npx @nestjs/cli generate module sheetjs
npx @nestjs/cli generate controller sheetjs
```
3) Add `multer` to the new module by editing `src/sheetjs/sheetjs.module.ts`.
The highlighted lines should be added to the file:
```ts title="src/sheetjs/sheetjs.module.ts"
import { Module } from '@nestjs/common';
import { SheetjsController } from './sheetjs.controller';
// highlight-next-line
import { MulterModule } from '@nestjs/platform-express';
@Module({
// highlight-start
imports: [
MulterModule.register({
dest: './upload',
}),
],
// highlight-end
controllers: [SheetjsController]
})
export class SheetjsModule {}
```
4) Copy the `src/sheetjs/sheetjs.controller.ts` example from earlier, replacing
the contents of the existing file.
5) Start the server with
```bash
npx @nestjs/cli start
```
3) Test POST requests using <https://sheetjs.com/pres.numbers>:
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:3000/sheetjs/upload
```
The response should show the data in CSV rows.
4) Test GET requests by opening `http://localhost:3000/sheetjs/download` in your browser.
It should prompt to download `SheetJSNest.xlsx`
</details>
#### Fastify
:::note
This demo was verified on 2023 August 27 using `fastify@4.22.0`
:::
_Reading Data_
`@fastify/multipart`, which uses `busbuy` under the hood, can be registered:
```js
/* load SheetJS Library */
const XLSX = require("xlsx");
/* load fastify and enable body parsing */
const fastify = require('fastify')({logger: true});
// highlight-next-line
fastify.register(require('@fastify/multipart'), { attachFieldsToBody: true });
```
Once registered with the option `attachFieldsToBody`, route handlers can use
`req.body` directly:
```js
/* POST / reads submitted file and exports to requested format */
fastify.post('/', async(req, reply) => {
/* "file" is the name of the field in the HTML form*/
const file = req.body.upload;
/* toBuffer returns a promise that resolves to a Buffer */
// highlight-next-line
const buf = await file.toBuffer();
/* `XLSX.read` can read the Buffer */
const wb = XLSX.read(buf);
/* reply with a CSV */
reply.send(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
```
:::caution pass
Out of the box, Fastify will return an error `FST_ERR_CTP_BODY_TOO_LARGE` when
processing large spreadsheets (`statusCode 413`). This is a Fastify issue.
The default body size limit (including all uploaded files and fields) is 1 MB.
It can be increased by setting the `bodyLimit` option during server creation:
```js
/* increase request body size limit to 5MB = 5 * 1024 * 1024 bytes */
const fastify = require('fastify')({bodyLimit: 5 * 1024 * 1024});
```
:::
_Writing Data_
The `Content-Disposition` header must be set manually:
```js
/* GET / returns a workbook */
fastify.get('/', (req, reply) => {
/* make a workbook */
var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
/* write to Buffer */
const buf = XLSX.write(wb, {type:"buffer", bookType: "xlsx"});
/* set Content-Disposition header and send data */
// highlight-next-line
reply.header('Content-Disposition', 'attachment; filename="SheetJSFastify.xlsx"').send(buf);
});
```
<details><summary><b>Testing</b> (click to show)</summary>
0) Save the following snippet to `SheetJSFastify.js`:
```js title="SheetJSFastify.js"
/* load SheetJS Library */
const XLSX = require("xlsx");
/* load fastify and enable body parsing */
const fastify = require('fastify')({logger: true});
fastify.register(require('@fastify/multipart'), { attachFieldsToBody: true });
/* GET / returns a workbook */
fastify.get('/', (req, reply) => {
/* make a workbook */
var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
/* write to Buffer */
const buf = XLSX.write(wb, {type:"buffer", bookType: "xlsx"});
/* set Content-Disposition header and send data */
reply.header('Content-Disposition', 'attachment; filename="SheetJSFastify.xlsx"').send(buf);
});
/* POST / reads submitted file and exports to requested format */
fastify.post('/', async(req, reply) => {
/* "file" is the name of the field in the HTML form*/
const file = req.body.upload;
/* toBuffer returns a promise that resolves to a Buffer */
const wb = XLSX.read(await file.toBuffer());
/* send back a CSV */
reply.send(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
/* start */
fastify.listen({port: process.env.PORT || 3000}, (err, addr) => { if(err) throw err; });
```
1) Install dependencies:
<CodeBlock language="bash">{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz fastify @fastify/multipart`}
</CodeBlock>
2) Start server
```bash
node SheetJSFastify.js
```
3) Test POST requests using <https://sheetjs.com/pres.numbers>:
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:3000/
```
The response should show the data in CSV rows.
4) Test GET requests by opening `http://localhost:3000/` in your browser.
It should prompt to download `SheetJSFastify.xlsx`
</details>
### Worker Threads
NodeJS "Worker Threads" were introduced in v14 and eventually marked as stable
in v16. Coupled with `AsyncResource`, a simple thread pool enables processing
without blocking the server! The official NodeJS docs include a sample worker
pool implementation.
This example uses ExpressJS to create a general XLSX conversion service, but
the same approach applies to any NodeJS server side framework.
When reading large files, it is strongly recommended to run the body parser in
the main server process. Body parsers like `formidable` will write uploaded
files to the filesystem, and the file path should be passed to the worker (and
the worker would be responsible for reading and cleaning up the files).
:::note pass
The `child_process` module can also spawn [command-line tools](/docs/demos/cli).
That approach is not explored in this demo.
:::
<details><summary><b>Complete Example</b> (click to show)</summary>
:::note
This demo was last tested on 2023 August 27 with NodeJS 20.5.1 + ExpressJS
4.18.2 + Formidable 2.1.1
:::
0) Create a simple ECMAScript-Module-enabled `package.json`:
```json title="package.json"
{ "type": "module" }
```
1) Install the dependencies:
<CodeBlock language="bash">{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz express@4.18.2 formidable@2.1.1`}
</CodeBlock>
2) Create a worker script `worker.js` that listens for messages. When a message
is received, it will read the file from the filesystem, generate and pass back a
new XLSX file, and delete the original file:
```js title="worker.js"
/* load the worker_threads module */
import { parentPort } from 'node:worker_threads';
/* load the SheetJS module and hook to FS */
import { set_fs, readFile, write } from 'xlsx';
import * as fs from 'fs';
set_fs(fs);
/* the server will send a message with the `path` field */
parentPort.on('message', (task) => {
/* highlight-start */
// read file
const wb = readFile(task.path, { dense: true });
// send back XLSX
parentPort.postMessage(write(wb, { type: "buffer", bookType: "xlsx" }));
/* highlight-end */
// remove file
fs.unlink(task.path, ()=>{});
});
```
3) Download [`worker_pool.js`](pathname:///server/worker_pool.js):
```bash
curl -LO https://docs.sheetjs.com/server/worker_pool.js
```
(this is a slightly modified version of the example in the NodeJS docs)
4) Save the following server code to `main.mjs`:
```js title="main.mjs"
/* load dependencies */
import os from 'node:os';
import process from 'node:process'
import express from 'express';
import formidable from 'formidable';
/* load worker pool */
import WorkerPool from './worker_pool.js';
const pool = new WorkerPool(os.cpus().length);
process.on("beforeExit", () => { pool.close(); })
/* create server */
const app = express();
app.post('/', (req, res, next) => {
// parse body
const form = formidable({});
form.parse(req, (err, fields, files) => {
// look for "upload" field
if(err) return next(err);
if(!files["upload"]) return next(new Error("missing `upload` file"));
// send a message to the worker with the path to the uploaded file
// highlight-next-line
pool.runTask({ path: files["upload"].filepath }, (err, result) => {
if(err) return next(err);
// send the file back as an attachment
res.attachment("SheetJSPool.xlsx");
res.status(200).end(result);
});
});
});
// start server
app.listen(7262, () => { console.log(`Example app listening on port 7262`); });
```
5) Run the server:
```bash
node main.mjs
```
Test with the [`pres.numbers` sample file](https://sheetjs.com/pres.numbers):
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:7262/ -J -O
```
This will generate `SheetJSPool.xlsx`.
</details>
## Deno
:::caution pass
Many hosted services like Deno Deploy do not offer filesystem access.
This breaks web frameworks that use the filesystem in body parsing.
:::
Deno provides the basic elements to implement a web server. It does not provide
a body parser out of the box.
#### Drash
In testing, [Drash](https://drash.land/drash/) had an in-memory body parser
which could handle file uploads on hosted services like Deno Deploy.
_Reading Data_
`Request#bodyParam` reads body parameters. For uploaded files, the `content`
property is a `Uint8Array` which can be parsed with the SheetJS `read` method[^1].
This example server responds to POST requests. The server will look for a file
in the request body under the `"upload"` key. If a file is present, the server
will parse the file, generate an HTML table using the `sheet_to_html` method[^2]
and respond with the HTML code:
<CodeBlock language="ts">{`\
// @deno-types="https://cdn.sheetjs.com/xlsx-${current}/package/types/index.d.ts"
import { read, utils } from 'https://cdn.sheetjs.com/xlsx-${current}/package/xlsx.mjs';
\n\
import * as Drash from "https://cdn.jsdelivr.net/gh/drashland/drash@v2.8.0/mod.ts";
\n\
class ParseResource extends Drash.Resource {
public paths = ["/"];
\n\
public POST(request: Drash.Request, response: Drash.Response) {
// assume a form upload like <input type="file" id="upload" name="upload">
// highlight-next-line
const file = request.bodyParam<Drash.Types.BodyFile>("upload");
if (!file) throw new Error("File is required!");
// highlight-next-line
var wb = read(file.content);
return response.html(utils.sheet_to_html(wb.Sheets[wb.SheetNames[0]]));
}
}`}
</CodeBlock>
_Writing Data_
Headers are manually set with `Response#headers.set` while the raw body is set
with `Response#send`. The raw body can be `Uint8Array` or `ArrayBuffer` objects.
Given a SheetJS workbook object, the `write` method using `type: "buffer"`[^3]
generates data objects compatible with Drash.
This example server responds to GET requests. The server will generate a SheetJS
worksheet object from an array of arrays[^4], build up a new workbook using the
`book_new`[^5] and `book_append_sheet`[^6] utility methods, generate a XLSX file
using `write`, and send the file with appropriate headers to initiate a download
with file name `"SheetJSDrash.xlsx"`:
<CodeBlock language="ts">{`\
// @deno-types="https://cdn.sheetjs.com/xlsx-${current}/package/types/index.d.ts"
import { utils, write } from 'https://cdn.sheetjs.com/xlsx-${current}/package/xlsx.mjs';
\n\
import * as Drash from "https://cdn.jsdelivr.net/gh/drashland/drash@v2.8.0/mod.ts";
\n\
class WriteResource extends Drash.Resource {
public paths = ["/export"];
\n\
public GET(request: Drash.Request, response: Drash.Response): void {
// create some fixed workbook
const data = ["SheetJS".split(""), [5,4,3,3,7,9,5]];
const ws = utils.aoa_to_sheet(data);
const wb = utils.book_new(); utils.book_append_sheet(wb, ws, "data");
// write the workbook to XLSX as a Uint8Array
// highlight-next-line
const file = write(wb, { bookType: "xlsx", type: "buffer"});
// set headers
response.headers.set("Content-Disposition", 'attachment; filename="SheetJSDrash.xlsx"');
// send data
// highlight-next-line
return response.send("application/vnd.ms-excel", file);
}
}`}
</CodeBlock>
<details><summary><b>Complete Example</b> (click to show)</summary>
:::note
This demo was last tested on 2023 August 18 against Drash 2.8.0 and Deno 1.36.1.
:::
1) Download [`SheetJSDrash.ts`](pathname:///server/SheetJSDrash.ts):
```bash
curl -LO https://docs.sheetjs.com/server/SheetJSDrash.ts
```
2) Run the server:
```bash
deno run --allow-net SheetJSDrash.ts
```
3) Download the test file <https://sheetjs.com/pres.numbers>
4) Open `http://localhost:7262/` in your browser.
Click "Choose File" and select `pres.numbers`. Then click "Submit"
The page should show the contents of the file as an HTML table.
5) Open `http://localhost:7262/export` in your browser.
The page should attempt to download `SheetJSDrash.xlsx` . Open the new file.
</details>
[^1]: See [`read` in "Reading Files"](/docs/api/parse-options)
[^2]: See [`sheet_to_html` in "Utilities"](/docs/api/utilities/html#html-table-output)
[^3]: See [`write` in "Writing Files"](/docs/api/write-options)
[^4]: See [`aoa_to_sheet` in "Utilities"](/docs/api/utilities/array#array-of-arrays-input)
[^5]: See [`book_new` in "Utilities"](/docs/api/utilities/wb)
[^6]: See [`book_append_sheet` in "Utilities"](/docs/api/utilities/wb)

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@ -0,0 +1,174 @@
---
title: Sheets in ExpressJS
sidebar_label: ExpressJS
pagination_prev: demos/net/network
pagination_next: demos/net/email
---
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
[ExpressJS](https://expressjs.com/) is a lightweight NodeJS framework for
building server-side applications.
[SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing
data from spreadsheets.
This demo uses ExpressJS and SheetJS to read and write data. We'll explore how
to parse uploaded files in a POST request handler and respond to GET requests
with downloadable spreadsheets.
The ["Complete Example"](#complete-example) section includes a complete server.
:::note
This demo was tested on 2023 October 16 using `express-formidable@1.2.0` and
ExpressJS `4.18.2`
:::
## Integration Details
The [SheetJS NodeJS module](/docs/getting-started/installation/nodejs) can be
imported from scripts that use ExpressJS.
### Exporting Data to Workbooks (GET)
The SheetJS `write` method[^1] with the option `type: "buffer"` generates NodeJS
Buffer objects containing the raw file data.
ExpressJS can directly handle `Buffer` data in `Response#end`[^2].
The exported filename can be specified using `Response#attachment`[^3].
The following demo ExpressJS server will respond to GET requests to `/download`
with a XLSX spreadsheet. In this example, the SheetJS `aoa_to_sheet` method[^4]
generates a sheet object and the `book_new` and `book_append_sheet` helpers[^5]
build the workbook object.
```js
var XLSX = require('xlsx'), express = require('express');
/* create app */
var app = express();
app.get('/download', function(req, res) {
/* generate workbook object */
var ws = XLSX.utils.aoa_to_sheet(["SheetJS".split(""), [5,4,3,3,7,9,5]]);
var wb = XLSX.utils.book_new(); XLSX.utils.book_append_sheet(wb, ws, "Data");
// highlight-start
/* generate buffer */
var buf = XLSX.write(wb, {type: "buffer", bookType: "xlsx"});
/* set headers */
res.attachment("SheetJSExpress.xlsx");
/* respond with file data */
res.status(200).end(buf);
// highlight-end
});
app.listen(+process.env.PORT||3000);
```
### Parsing Uploaded Files (POST)
The `express-formidable` middleware is powered by the `formidable` parser. It
adds a `files` object to the request.
Each value in the `files` object has a `path` property which represents the path
to the file in the filesystem. The SheetJS `readFile` method[^6] can read the
file and generate a workbook object[^7].
The following demo ExpressJS server will respond to POST requests to `/upload`.
Assuming the `upload` field of the form data is the file, the SheetJS `read`
method will parse the file. CSV rows are generated from the first worksheet
using the SheetJS `sheet_to_csv` method[^8].
```js
var XLSX = require('xlsx'), express = require('express');
/* create app */
var app = express();
/* add express-formidable middleware */
// highlight-next-line
app.use(require('express-formidable')());
/* route for handling uploaded data */
app.post('/upload', function(req, res) {
// highlight-start
var f = req.files["upload"]; // <input type="file" id="upload" name="upload">
var wb = XLSX.readFile(f.path);
// highlight-end
/* respond with CSV data from the first sheet */
res.status(200).end(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
app.listen(+process.env.PORT||3000);
```
## Complete Example
1) Save the code sample to `SheetJSExpressCSV.js`:
```js title="SheetJSExpressCSV.js"
var XLSX = require('xlsx'), express = require('express');
/* create app */
var app = express();
/* add express-formidable middleware */
// highlight-next-line
app.use(require('express-formidable')());
/* route for handling uploaded data */
app.post('/upload', function(req, res) {
// highlight-start
var f = req.files["upload"]; // <input type="file" id="upload" name="upload">
var wb = XLSX.readFile(f.path);
// highlight-end
/* respond with CSV data from the first sheet */
res.status(200).end(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
app.get('/download', function(req, res) {
/* generate workbook object */
var ws = XLSX.utils.aoa_to_sheet(["SheetJS".split(""), [5,4,3,3,7,9,5]]);
var wb = XLSX.utils.book_new(); XLSX.utils.book_append_sheet(wb, ws, "Data");
// highlight-start
/* generate buffer */
var buf = XLSX.write(wb, {type: "buffer", bookType: "xlsx"});
/* set headers */
res.attachment("SheetJSExpress.xlsx");
/* respond with file data */
res.status(200).end(buf);
// highlight-end
});
app.listen(+process.env.PORT||3000);
```
2) Install dependencies:
<CodeBlock language="bash">{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz express@4.18.2 express-formidable@1.2.0`}
</CodeBlock>
3) Start server (note: it will not print anything to console when running)
```bash
node SheetJSExpressCSV.js
```
4) Test POST requests using <https://sheetjs.com/pres.numbers>:
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:3000/upload
```
The response should show the data in CSV rows.
5) Test GET requests by opening `http://localhost:3000/download` in your browser.
It should prompt to download `SheetJSExpress.xlsx`
[^1]: See [`write` in "Writing Files"](/docs/api/write-options)
[^2]: See [`res.end`](https://expressjs.com/en/4x/api.html#res.end) in the ExpressJS documentation.
[^3]: See [`res.attachment`](https://expressjs.com/en/4x/api.html#res.attachment) in the ExpressJS documentation.
[^4]: See [`aoa_to_sheet` in "Utilities"](/docs/api/utilities/array#array-of-arrays-input)
[^5]: See ["Workbook Helpers" in "Utilities"](/docs/api/utilities/wb) for details on `book_new` and `book_append_sheet`.
[^6]: See [`readFile` in "Reading Files"](/docs/api/parse-options)
[^7]: See ["Workbook Object"](/docs/csf/book)
[^8]: See [`sheet_to_csv` in "CSV and Text"](/docs/api/utilities/csv#delimiter-separated-output)

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@ -0,0 +1,143 @@
---
title: Sheets in Drash
sidebar_label: Drash
pagination_prev: demos/net/network
pagination_next: demos/net/email
---
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
[Drash](https://drash.land/drash/) is a Deno server-side framework. The body
parser works in memory and can handle file uploads on hosted services.
[SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing
data from spreadsheets.
This demo uses Drash and SheetJS to read and write data. We'll explore how to
parse uploaded files in a POST request handler and respond to GET requests with
downloadable spreadsheets.
The ["Complete Example"](#complete-example) section includes a complete server.
:::note
This demo was last tested on 2023 October 16 against Drash 2.8.1 and Deno 1.37.2.
:::
## Integration Details
The [SheetJS Deno module](/docs/getting-started/installation/nodejs) can be
imported from Drash server scripts.
### Reading Data
`Request#bodyParam` reads body parameters. For uploaded files, the `content`
property is a `Uint8Array` which can be parsed with the SheetJS `read` method[^1].
This example server responds to POST requests. The server will look for a file
in the request body under the `"upload"` key. If a file is present, the server
will parse the file, generate an HTML table using the `sheet_to_html` method[^2]
and respond with the HTML code:
<CodeBlock language="ts">{`\
// @deno-types="https://cdn.sheetjs.com/xlsx-${current}/package/types/index.d.ts"
import { read, utils } from 'https://cdn.sheetjs.com/xlsx-${current}/package/xlsx.mjs';
\n\
import * as Drash from "https://cdn.jsdelivr.net/gh/drashland/drash@v2.8.1/mod.ts";
\n\
class ParseResource extends Drash.Resource {
public paths = ["/"];
\n\
public POST(request: Drash.Request, response: Drash.Response) {
// assume a form upload like <input type="file" id="upload" name="upload">
// highlight-next-line
const file = request.bodyParam<Drash.Types.BodyFile>("upload");
if (!file) throw new Error("File is required!");
\n\
// read file
// highlight-next-line
var wb = read(file.content);
\n\
// respond with HTML from first worksheet
var ws = wb.Sheets[wb.SheetNames[0]];
var html = utils.sheet_to_html(html)
return response.html(html);
}
}`}
</CodeBlock>
### Writing Data
Headers are manually set with `Response#headers.set` while the raw body is set
with `Response#send`. The raw body can be `Uint8Array` or `ArrayBuffer` objects.
Given a SheetJS workbook object, the `write` method using `type: "buffer"`[^3]
generates data objects compatible with Drash.
This example server responds to GET requests. The server will generate a SheetJS
worksheet object from an array of arrays[^4], build up a new workbook using the
`book_new`[^5] and `book_append_sheet`[^6] utility methods, generate a XLSX file
using `write`, and send the file with appropriate headers to initiate a download
with file name `"SheetJSDrash.xlsx"`:
<CodeBlock language="ts">{`\
// @deno-types="https://cdn.sheetjs.com/xlsx-${current}/package/types/index.d.ts"
import { utils, write } from 'https://cdn.sheetjs.com/xlsx-${current}/package/xlsx.mjs';
\n\
import * as Drash from "https://cdn.jsdelivr.net/gh/drashland/drash@v2.8.1/mod.ts";
\n\
class WriteResource extends Drash.Resource {
public paths = ["/export"];
\n\
public GET(request: Drash.Request, response: Drash.Response): void {
// create some fixed workbook
const data = ["SheetJS".split(""), [5,4,3,3,7,9,5]];
const ws = utils.aoa_to_sheet(data);
const wb = utils.book_new(); utils.book_append_sheet(wb, ws, "data");
\n\
// write the workbook to XLSX as a Uint8Array
// highlight-next-line
const file = write(wb, { bookType: "xlsx", type: "buffer"});
// set headers
response.headers.set("Content-Disposition", 'attachment; filename="SheetJSDrash.xlsx"');
// send data
// highlight-next-line
return response.send("application/vnd.ms-excel", file);
}
}`}
</CodeBlock>
## Complete Example
1) Download [`SheetJSDrash.ts`](pathname:///drash/SheetJSDrash.ts):
```bash
curl -LO https://docs.sheetjs.com/drash/SheetJSDrash.ts
```
2) Run the server:
```bash
deno run --allow-net SheetJSDrash.ts
```
3) Download the test file <https://sheetjs.com/pres.numbers>
4) Open `http://localhost:7262/` in your browser.
Click "Choose File" and select `pres.numbers`. Then click "Submit"
The page should show the contents of the file as an HTML table.
5) Open `http://localhost:7262/export` in your browser.
The page should attempt to download `SheetJSDrash.xlsx` . Open the new file.
[^1]: See [`read` in "Reading Files"](/docs/api/parse-options)
[^2]: See [`sheet_to_html` in "Utilities"](/docs/api/utilities/html#html-table-output)
[^3]: See [`write` in "Writing Files"](/docs/api/write-options)
[^4]: See [`aoa_to_sheet` in "Utilities"](/docs/api/utilities/array#array-of-arrays-input)
[^5]: See [`book_new` in "Utilities"](/docs/api/utilities/wb)
[^6]: See [`book_append_sheet` in "Utilities"](/docs/api/utilities/wb)

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@ -0,0 +1,233 @@
---
title: Sheets in NestJS
sidebar_label: NestJS
pagination_prev: demos/net/network
pagination_next: demos/net/email
---
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
[NestJS](https://nestjs.com/) is a NodeJS framework for building server-side
applications.
[SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing
data from spreadsheets.
This demo uses NestJS and SheetJS to read and write data. We'll explore how to
parse uploaded files in a POST request handler and respond to GET requests with
downloadable spreadsheets.
The ["Complete Example"](#complete-example) section includes a complete server.
:::note
This demo was tested on 2023 October 15 using NestJS `10.2.7`.
:::
## Integration Details
The [SheetJS NodeJS module](/docs/getting-started/installation/nodejs) can be
imported from NestJS controller scripts.
:::caution pass
NestJS does not follow the conventional NodeJS server code structure.
It is strongly recommended to review the official documentation. The official
documentation covers Controller structure and various JS Decorators.
:::
### Exporting Data to Workbooks (GET)
The SheetJS `write` method[^1] with the option `type: "buffer"` generates NodeJS
Buffer objects containing the raw file data.
NestJS strongly recommends wrapping the Buffer in a `StreamableFile` object[^2].
The exported filename can be specified in a `@Header` decorator[^3]
The following demo NestJS Controller will respond to GET requests to `/download`
with a XLSX spreadsheet. In this example, the SheetJS `aoa_to_sheet` method[^4]
generates a sheet object and the `book_new` and `book_append_sheet` helpers[^5]
build the workbook object.
```ts title="src/sheetjs/sheetjs.controller.js"
import { Controller, Get, Header, StreamableFile } from '@nestjs/common';
import { utils, write } from 'xlsx';
@Controller('sheetjs')
export class SheetjsController {
@Get('download')
@Header('Content-Disposition', 'attachment; filename="SheetJSNest.xlsx"')
async downloadXlsxFile(): Promise<StreamableFile> {
var ws = utils.aoa_to_sheet(["SheetJS".split(""), [5,4,3,3,7,9,5]]);
var wb = utils.book_new(); utils.book_append_sheet(wb, ws, "Data");
// highlight-start
/* generate buffer */
var buf = write(wb, {type: "buffer", bookType: "xlsx"});
/* Return a streamable file */
return new StreamableFile(buf);
// highlight-end
}
}
```
### Parsing Uploaded Files (POST)
:::note pass
[The NestJS documentation](https://docs.nestjs.com/techniques/file-upload) has
detailed instructions for file upload support.
:::
As explained in the NestJS documentation, in a POST request handler, the
`FileInterceptor` interceptor and `UploadedFile` decorator are used in tandem to
expose a file uploaded with a specified key.
The file object has a `buffer` property which represents the raw bytes. The
SheetJS `read` method[^6] can parse the Buffer into a workbook object[^7].
The following demo NestJS Controller will respond to POST requests to `/upload`.
Assuming the `upload` field of the form data is the file, the SheetJS `read`
method will parse the file. CSV rows are generated from the first worksheet
using the SheetJS `sheet_to_csv` method[^8].
```ts title="src/sheetjs/sheetjs.controller.js"
import { Controller, Post, UploadedFile, UseInterceptors } from '@nestjs/common';
import { FileInterceptor } from '@nestjs/platform-express';
import { read, utils } from 'xlsx';
@Controller('sheetjs')
export class SheetjsController {
@Post('upload') // <input type="file" id="upload" name="upload">
@UseInterceptors(FileInterceptor('upload'))
async uploadXlsxFile(@UploadedFile() file: Express.Multer.File) {
/* file.buffer is a Buffer */
// highlight-next-line
const wb = read(file.buffer);
/* generate CSV of first worksheet */
return utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]);
}
}
```
## Complete Example
1) Create a new NestJS project:
```bash
npx @nestjs/cli@latest new -p npm sheetjs-nest
cd sheetjs-nest
```
2) Install the `@types/multer` package as a development dependency:
```bash
npm i --save-dev @types/multer
```
3) Install the SheetJS library:
<CodeBlock language="bash">{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz`}
</CodeBlock>
4) Make a folder for uploaded files:
```bash
mkdir -p upload
```
5) Create a new controller:
```bash
npx @nestjs/cli generate controller sheetjs
```
6) Replace `src/sheetjs/sheetjs.controller.ts` with the following code block:
```ts title="src/sheetjs/sheetjs.controller.js"
import { Controller, Get, Header, Post, StreamableFile, UploadedFile, UseInterceptors } from '@nestjs/common';
import { FileInterceptor } from '@nestjs/platform-express';
import { read, utils, write } from 'xlsx';
@Controller('sheetjs')
export class SheetjsController {
@Post('upload') // <input type="file" id="upload" name="upload">
@UseInterceptors(FileInterceptor('upload'))
async uploadXlsxFile(@UploadedFile() file: Express.Multer.File) {
/* file.path is a path to the workbook */
const wb = read(file.buffer);
/* generate CSV of first worksheet */
return utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]);
}
@Get('download')
@Header('Content-Disposition', 'attachment; filename="SheetJSNest.xlsx"')
async downloadXlsxFile(): Promise<StreamableFile> {
var ws = utils.aoa_to_sheet(["SheetJS".split(""), [5,4,3,3,7,9,5]]);
var wb = utils.book_new(); utils.book_append_sheet(wb, ws, "Data");
/* generate buffer */
var buf = write(wb, {type: "buffer", bookType: "xlsx"});
/* Return a streamable file */
return new StreamableFile(buf);
}
}
```
7) Start the server with
```bash
npx @nestjs/cli start
```
:::note
In the most recent test, the process failed with a message referencing Multer:
```
src/sheetjs/sheetjs.controller.ts:9:54 - error TS2694: Namespace 'global.Express' has no exported member 'Multer'.
9 async uploadXlsxFile(@UploadedFile() file: Express.Multer.File) {
~~~~~~
```
This error indicates that `@types/multer` is not available.
**This is a bug in the `npm` client**
The recommended fix is to install `@types/multer` again:
```bash
npm i --save-dev @types/multer
```
:::
8) Test POST requests in the terminal with <https://sheetjs.com/pres.numbers>:
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:3000/sheetjs/upload
```
The response should show the data in CSV rows.
9) Test GET requests by opening `http://localhost:3000/sheetjs/download` in a
web browser.
The browser should attempt to download `SheetJSNest.xlsx`. Save the file and
open in a spreadsheet editor.
[^1]: See [`write` in "Writing Files"](/docs/api/write-options)
[^2]: See ["Streaming files"](https://docs.nestjs.com/techniques/streaming-files) in the NestJS documentation.
[^3]: See ["Headers"](https://docs.nestjs.com/controllers#headers) in the NestJS documentation.
[^4]: See [`aoa_to_sheet` in "Utilities"](/docs/api/utilities/array#array-of-arrays-input)
[^5]: See ["Workbook Helpers" in "Utilities"](/docs/api/utilities/wb) for details on `book_new` and `book_append_sheet`.
[^6]: See [`read` in "Reading Files"](/docs/api/parse-options)
[^7]: See ["Workbook Object"](/docs/csf/book)
[^8]: See [`sheet_to_csv` in "CSV and Text"](/docs/api/utilities/csv#delimiter-separated-output)

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@ -0,0 +1,187 @@
---
title: Sheets in FastifyJS
sidebar_label: FastifyJS
pagination_prev: demos/net/network
pagination_next: demos/net/email
---
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
[FastifyJS](https://openjsf.org/projects/) is a NodeJS web framework.
[SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing
data from spreadsheets.
This demo uses FastifyJS and SheetJS to read and write data. We'll explore how
to parse uploaded files in a POST request handler and respond to GET requests
with downloadable spreadsheets.
The ["Complete Example"](#complete-example) section includes a complete server.
:::note
This demo was verified on 2023 October 16 using `fastify@4.24.2`
:::
## Integration Details
The [SheetJS NodeJS module](/docs/getting-started/installation/nodejs) can be
imported from scripts that use FastifyJS.
### Exporting Data to Workbooks (GET)
The SheetJS `write` method[^1] with the option `type: "buffer"` generates NodeJS
Buffer objects containing the raw file data.
FastifyJS can directly handle `Buffer` data in `Response#end`
The exported filename can be specified using the `Content-Disposition` header.
The following demo FastifyJS server will respond to GET requests to `/download`
with a XLSX spreadsheet. In this example, the SheetJS `aoa_to_sheet` method[^2]
generates a sheet object and the `book_new` and `book_append_sheet` helpers[^3]
build the workbook object.
```js
/* GET / returns a workbook */
fastify.get('/', (req, reply) => {
/* make a workbook */
var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
/* write to Buffer */
const buf = XLSX.write(wb, {type:"buffer", bookType: "xlsx"});
/* set Content-Disposition header and send data */
// highlight-next-line
reply.header('Content-Disposition', 'attachment; filename="SheetJSFastify.xlsx"').send(buf);
});
```
### Parsing Uploaded Files (POST)
`@fastify/multipart`, which uses `busbuy` under the hood, must be registered:
```js
/* load SheetJS Library */
const XLSX = require("xlsx");
/* load fastify and enable body parsing */
const fastify = require('fastify')({logger: true});
// highlight-next-line
fastify.register(require('@fastify/multipart'), { attachFieldsToBody: true });
```
Once registered with the option `attachFieldsToBody`, route handlers can use
`req.body` directly.
Each file object in the body has a `toBuffer` method that resolves to a Buffer
object. The SheetJS `read` method[^4] can read the Buffer and generate a
workbook object[^5].
The following demo FastifyJS server will respond to POST requests to `/upload`.
Assuming the `upload` field of the form data is the file, the SheetJS `read`
method will parse the file. CSV rows are generated from the first worksheet
using the SheetJS `sheet_to_csv` method[^6].
```js
/* POST / reads submitted file and exports to requested format */
fastify.post('/', async(req, reply) => {
/* "file" is the name of the field in the HTML form*/
const file = req.body.upload;
/* toBuffer returns a promise that resolves to a Buffer */
// highlight-next-line
const buf = await file.toBuffer();
/* `XLSX.read` can read the Buffer */
const wb = XLSX.read(buf);
/* reply with a CSV */
reply.send(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
```
:::caution pass
Out of the box, Fastify will return an error `FST_ERR_CTP_BODY_TOO_LARGE` when
processing large spreadsheets (`statusCode 413`). This is a Fastify issue.
The default body size limit (including all uploaded files and fields) is 1 MB.
It can be increased by setting the `bodyLimit` option during server creation:
```js
/* increase request body size limit to 5MB = 5 * 1024 * 1024 bytes */
const fastify = require('fastify')({bodyLimit: 5 * 1024 * 1024});
```
:::
## Complete Example
0) Save the following snippet to `SheetJSFastify.js`:
```js title="SheetJSFastify.js"
/* load SheetJS Library */
const XLSX = require("xlsx");
/* load fastify and enable body parsing */
const fastify = require('fastify')({logger: true});
fastify.register(require('@fastify/multipart'), { attachFieldsToBody: true });
/* GET / returns a workbook */
fastify.get('/', (req, reply) => {
/* make a workbook */
var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
/* write to Buffer */
const buf = XLSX.write(wb, {type:"buffer", bookType: "xlsx"});
/* set Content-Disposition header and send data */
reply.header('Content-Disposition', 'attachment; filename="SheetJSFastify.xlsx"').send(buf);
});
/* POST / reads submitted file and exports to requested format */
fastify.post('/', async(req, reply) => {
/* "file" is the name of the field in the HTML form*/
const file = req.body.upload;
/* toBuffer returns a promise that resolves to a Buffer */
const wb = XLSX.read(await file.toBuffer());
/* send back a CSV */
reply.send(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
/* start */
fastify.listen({port: process.env.PORT || 3000}, (err, addr) => { if(err) throw err; });
```
1) Install dependencies:
<CodeBlock language="bash">{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz fastify@4.24.2 @fastify/multipart@8.0.0`}
</CodeBlock>
2) Start server
```bash
node SheetJSFastify.js
```
3) Test POST requests using <https://sheetjs.com/pres.numbers>:
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:3000/
```
The response should show the data in CSV rows.
4) Test GET requests by opening `http://localhost:3000/` in your browser.
It should prompt to download `SheetJSFastify.xlsx`
[^1]: See [`write` in "Writing Files"](/docs/api/write-options)
[^2]: See [`aoa_to_sheet` in "Utilities"](/docs/api/utilities/array#array-of-arrays-input)
[^3]: See ["Workbook Helpers" in "Utilities"](/docs/api/utilities/wb) for details on `book_new` and `book_append_sheet`.
[^4]: See [`readFile` in "Reading Files"](/docs/api/parse-options)
[^5]: See ["Workbook Object"](/docs/csf/book)
[^6]: See [`sheet_to_csv` in "CSV and Text"](/docs/api/utilities/csv#delimiter-separated-output)

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@ -0,0 +1,5 @@
{
"label": "HTTP Server Processing",
"collapsed": false,
"position": 2
}

View File

@ -0,0 +1,246 @@
---
title: HTTP Server Processing
pagination_prev: demos/net/network
pagination_next: demos/net/email
---
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
Server-Side JS platforms like NodeJS and Deno have built-in APIs for listening
on network interfaces. They provide wrappers for requests and responses.
## Overview
#### Parsing Files in POST Requests
Typically servers receive form data with content type `multipart/form-data` or
`application/x-www-form-urlencoded`. The platforms themselves typically do not
provide "body parsing" functions, instead leaning on the community to supply
modules to take the encoded data and split into form fields and files.
NodeJS servers typically use a parser like `formidable`. In the example below,
`formidable` will write to file and `XLSX.readFile` will read the file:
```js
var XLSX = require("xlsx"); // This is using the CommonJS build
var formidable = require("formidable");
require("http").createServer(function(req, res) {
if(req.method !== "POST") return res.end("");
/* parse body and implement logic in callback */
// highlight-next-line
(new formidable.IncomingForm()).parse(req, function(err, fields, files) {
/* if successful, files is an object whose keys are param names */
// highlight-next-line
var file = files["upload"]; // <input type="file" id="upload" name="upload">
/* file.path is a location in the filesystem, usually in a temp folder */
// highlight-next-line
var wb = XLSX.readFile(file.filepath);
// print the first worksheet back as a CSV
res.end(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
});
}).listen(process.env.PORT || 3000);
```
`XLSX.read` will accept NodeJS buffers as well as `Uint8Array`, Base64 strings,
binary strings, and plain Arrays of bytes. This covers the interface types of
a wide variety of frameworks.
#### Writing Files in GET Requests
Typically server libraries use a response API that accepts `Uint8Array` data.
`XLSX.write` with the option `type: "buffer"` will generate data. To force the
response to be treated as an attachment, set the `Content-Disposition` header:
```js
var XLSX = require("xlsx"); // This is using the CommonJS build
require("http").createServer(function(req, res) {
if(req.method !== "GET") return res.end("");
var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
// highlight-start
res.setHeader('Content-Disposition', 'attachment; filename="SheetJS.xlsx"');
res.end(XLSX.write(wb, {type:"buffer", bookType: "xlsx"}));
// highlight-end
}).listen(process.env.PORT || 3000);
```
## NodeJS
When processing small files, the work is best handled in the server response
handler function. This approach is used in the "Framework Demos" section.
When processing large files, the direct approach will freeze the server. NodeJS
provides ["Worker Threads"](#worker-threads) for this exact use case.
### Framework Demos
#### Express
**[The exposition has been moved to a separate page.](/docs/demos/net/server/express)**
#### NestJS
**[The exposition has been moved to a separate page.](/docs/demos/net/server/nestjs)**
#### Fastify
**[The exposition has been moved to a separate page.](/docs/demos/net/server/fastify)**
### Worker Threads
NodeJS "Worker Threads" were introduced in v14 and eventually marked as stable
in v16. Coupled with `AsyncResource`, a simple thread pool enables processing
without blocking the server! The official NodeJS docs include a sample worker
pool implementation.
This example uses ExpressJS to create a general XLSX conversion service, but
the same approach applies to any NodeJS server side framework.
When reading large files, it is strongly recommended to run the body parser in
the main server process. Body parsers like `formidable` will write uploaded
files to the filesystem, and the file path should be passed to the worker (and
the worker would be responsible for reading and cleaning up the files).
:::note pass
The `child_process` module can also spawn [command-line tools](/docs/demos/cli).
That approach is not explored in this demo.
:::
<details><summary><b>Complete Example</b> (click to show)</summary>
:::note
This demo was last tested on 2023 August 27 with NodeJS 20.5.1 + ExpressJS
4.18.2 + Formidable 2.1.1
:::
0) Create a simple ECMAScript-Module-enabled `package.json`:
```json title="package.json"
{ "type": "module" }
```
1) Install the dependencies:
<CodeBlock language="bash">{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz express@4.18.2 formidable@2.1.1`}
</CodeBlock>
2) Create a worker script `worker.js` that listens for messages. When a message
is received, it will read the file from the filesystem, generate and pass back a
new XLSX file, and delete the original file:
```js title="worker.js"
/* load the worker_threads module */
import { parentPort } from 'node:worker_threads';
/* load the SheetJS module and hook to FS */
import { set_fs, readFile, write } from 'xlsx';
import * as fs from 'fs';
set_fs(fs);
/* the server will send a message with the `path` field */
parentPort.on('message', (task) => {
/* highlight-start */
// read file
const wb = readFile(task.path, { dense: true });
// send back XLSX
parentPort.postMessage(write(wb, { type: "buffer", bookType: "xlsx" }));
/* highlight-end */
// remove file
fs.unlink(task.path, ()=>{});
});
```
3) Download [`worker_pool.js`](pathname:///server/worker_pool.js):
```bash
curl -LO https://docs.sheetjs.com/server/worker_pool.js
```
(this is a slightly modified version of the example in the NodeJS docs)
4) Save the following server code to `main.mjs`:
```js title="main.mjs"
/* load dependencies */
import os from 'node:os';
import process from 'node:process'
import express from 'express';
import formidable from 'formidable';
/* load worker pool */
import WorkerPool from './worker_pool.js';
const pool = new WorkerPool(os.cpus().length);
process.on("beforeExit", () => { pool.close(); })
/* create server */
const app = express();
app.post('/', (req, res, next) => {
// parse body
const form = formidable({});
form.parse(req, (err, fields, files) => {
// look for "upload" field
if(err) return next(err);
if(!files["upload"]) return next(new Error("missing `upload` file"));
// send a message to the worker with the path to the uploaded file
// highlight-next-line
pool.runTask({ path: files["upload"].filepath }, (err, result) => {
if(err) return next(err);
// send the file back as an attachment
res.attachment("SheetJSPool.xlsx");
res.status(200).end(result);
});
});
});
// start server
app.listen(7262, () => { console.log(`Example app listening on port 7262`); });
```
5) Run the server:
```bash
node main.mjs
```
Test with the [`pres.numbers` sample file](https://sheetjs.com/pres.numbers):
```bash
curl -LO https://sheetjs.com/pres.numbers
curl -X POST -F upload=@pres.numbers http://localhost:7262/ -J -O
```
This will generate `SheetJSPool.xlsx`.
</details>
## Other Platforms
### Deno
:::caution pass
Many hosted services like Deno Deploy do not offer filesystem access.
This breaks web frameworks that use the filesystem in body parsing.
:::
Deno provides the basic elements to implement a web server. It does not provide
a body parser out of the box.
#### Drash
In testing, [Drash](https://drash.land/drash/) had an in-memory body parser
which could handle file uploads on hosted services like Deno Deploy.
**[The exposition has been moved to a separate page.](/docs/demos/net/server/drash)**

View File

@ -1,5 +1,6 @@
---
title: Electronic Mail
pagination_prev: demos/net/server/index
---
import current from '/version.js';

View File

@ -15,8 +15,8 @@ sidebar_custom_props:
IndexedDB is a very low-level API.
Browser vendors recommend using libraries or [WebSQL](/docs/demos/data/websql)
in production applications.
Browser vendors recommend using [WebSQL](/docs/demos/local/websql) or wrapper
libraries in production applications.
:::

View File

@ -354,7 +354,8 @@ required in NodeJS scripts.
### Connecting to S3
The `aws-sdk` module includes a function `S3` that performs the connection.
The `aws-sdk` module exports a function `S3` that performs the connection. The
function expects an options object that includes an API version and credentials.
Access keys for an IAM user[^9] must be used:
```js
@ -370,7 +371,6 @@ var s3 = new AWS.S3({
apiVersion: '2006-03-01',
credentials: { accessKeyId, secretAccessKey }
});
```
### Downloading Data