forked from sheetjs/docs.sheetjs.com
89 lines
2.9 KiB
JavaScript
89 lines
2.9 KiB
JavaScript
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const Knex = require('knex');
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const XLSX = require("xlsx");
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/* read file and get first worksheet */
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const oldwb = XLSX.readFile("pres.numbers");
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const oldws = oldwb.Sheets[oldwb.SheetNames[0]];
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/* create table and load data given an array of objects and a Knex connection */
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async function aoo_to_knex_table(knex, aoo, table_name) {
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/* define types that can be converted (e.g. boolean can be stored in float) */
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const T_FLOAT = ["float", "boolean"];
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const T_BOOL = ["boolean"];
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/* types is a map from column headers to Knex schema column type */
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const types = {};
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/* names is an ordered list of the column header names */
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const names = [];
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/* loop across each row object */
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aoo.forEach(row =>
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/* Object.entries returns a row of [key, value] pairs */
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Object.entries(row).forEach(([k,v]) => {
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/* If this is first occurrence, mark unknown and append header to names */
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if(!types[k]) { types[k] = ""; names.push(k); }
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/* skip null and undefined values */
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if(v == null) return;
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/* check and resolve type */
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switch(typeof v) {
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/* change type if it is empty or can be stored in a float */
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case "number": if(!types[k] || T_FLOAT.includes(types[k])) types[k] = "float"; break;
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/* change type if it is empty or can be stored in a boolean */
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case "boolean": if(!types[k] || T_BOOL.includes(types[k])) types[k] = "boolean"; break;
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/* no other type can hold strings */
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case "string": types[k] = "text"; break;
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default: types[k] = "text"; break;
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}
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})
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);
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/* Delete table if it exists in the DB */
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await knex.schema.dropTableIfExists(table_name);
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/* use column type info to create table */
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await knex.schema.createTable(table_name, (table) => {
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names.forEach(h => {
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/* call schema function e.g. table.text("Name"); table.float("Index"); */
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table[types[h] || "text"](h);
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});
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});
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/* insert each row */
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await knex.insert(aoo).into(table_name);
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return knex;
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}
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(async() => {
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/* open connection to SheetJSKnex.db */
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let knex = Knex({ client: 'better-sqlite3', connection: { filename: "SheetJSKnex.db" }, useNullAsDefault: true });
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try {
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/* generate array of objects from worksheet */
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const aoo = XLSX.utils.sheet_to_json(oldws);
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/* create table and load data */
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await aoo_to_knex_table(knex, aoo, "Test_Table");
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} finally {
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/* disconnect */
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knex.destroy();
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}
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/* reconnect to SheetJSKnex.db */
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knex = Knex({ client: 'better-sqlite3', connection: { filename: "SheetJSKnex.db" }, useNullAsDefault: true });
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try {
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/* get data from db */
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const aoo = await knex.select("*").from("Test_Table");
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/* export to file */
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const newws = XLSX.utils.json_to_sheet(aoo);
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const newwb = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(newwb, newws, "Export");
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XLSX.writeFile(newwb, "SheetJSKnex.xlsx");
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} finally { knex.destroy(); }
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})();
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