docs.sheetjs.com/docz/docs/03-demos/41-nosql.md

title
NoSQL Data Stores

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So-called "Schema-less" databases allow for arbitrary keys and values within the entries in the database. K/V stores and Objects add additional restrictions.

:::note

These data stores are capable of storing structured data. Those use cases are covered in the Database demo.

:::

Arbitrary Data to Spreadsheets

There is no natural way to translate arbitrarily shaped schemas to worksheets in a workbook. One common trick is to dedicate one worksheet to holding named keys. For example, considering the JS object:

{
  "title": "SheetDB",
  "metadata": {
    "author": "SheetJS",
    "code": 7262
  },
  "data": [
    { "Name": "Barack Obama", "Index": 44 },
    { "Name": "Donald Trump", "Index": 45 },
  ]
}

A dedicated worksheet should store the one-off named values:

XXX|        A        |    B    |
---+-----------------+---------+
 1 | Path            | Value   |
 2 | title           | SheetDB |
 3 | metadata.author | SheetJS |
 4 | metadata.code   |    7262 |

Data Stores

Redis

Redis has 5 core data types: "String", List", "Set", "Sorted Set", and "Hash". Since the keys and values are limited to simple strings (and numbers), it is possible to store complete databases in a single worksheet.

Mapping

The first row holds the data type and the second row holds the property name.

Strings can be stored in a unified String table. The first column holds keys and the second column holds values:

XXX|    A    |   B   |
---+---------+-------+
 1 | Strings |       |
 2 |         |       |
 3 | Hello   | World |
 4 | Sheet   | JS    |

The SheetJS array-of-arrays representation of the string table is an array of key/value pairs:

let aoa = ["Strings"]; aoa.length = 2; // [ "Strings", empty ]
const keys = await client.KEYS("*");
for(let key of keys) {
  const type = await client.TYPE(key);
  if(type == "string") aoa.push([key, await client.GET(key)]);
}

Lists are unidimensional and can be stored in their own columns.

XXX|    C    |
---+---------+
 1 | List    |
 2 | List1   |
 3 | List1V1 |
 4 | List1V2 |

The SheetJS array-of-arrays representation of lists is a column of values.

if(type == "list") {
  let values = await client.LRANGE(key, 0, -1);
  aoa = [ ["List"], [key] ].concat(values.map(v => [v]));
}

Sets are unidimensional and can be stored in their own columns.

XXX|   D   |
---+-------+
 1 | Set   |
 2 | Set1  |
 3 | Set1A |
 4 | Set1B |

The SheetJS array-of-arrays representation of sets is a column of values.

if(type == "set") {
  let values = await client.SMEMBERS(key);
  aoa = [ ["Set"], [key] ].concat(values.map(v => [v]));
}

Sorted Sets have an associated score which can be stored in the second column.

XXX|    E    | F |
---+---------+---+
 1 | Sorted  |   |
 2 | ZSet1   |   |
 3 | Key1    | 1 |
 4 | Key2    | 2 |

The SheetJS array-of-arrays representation is an array of key/score pairs.

if(type == "zset") {
  let values = await client.ZRANGE_WITHSCORES(key, 0, -1);
  aoa = [ ["Sorted"], [key] ].concat(values.map(v => [v.value, v.score]));
}

Hashes are stored like the string table, with key and value columns in order.

XXX|   G   |   H   |
---+-------+-------+
 1 | Hash  |       |
 2 | Hash1 |       |
 3 | Key1  | Val1  |
 4 | Key2  | Val2  |

The SheetJS array-of-arrays representation is an array of key/value pairs.

if(type == "hash") {
  let values = await client.HGETALL(key);
  aoa = [ ["Hash"], [key] ].concat(Object.entries(values));
}

Example

Complete Example (click to show)

0. Set up and start a local Redis server

1. Download the following scripts:

• SheetJSRedis.mjs
• SheetJSRedisTest.mjs

2. Install dependencies and run:

npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz redis
node SheetJSRedisTest.mjs

Inspect the output and compare with the data in SheetJSRedisTest.mjs.

Open SheetJSRedis.xlsx and verify the columns have the correct data

PouchDB

Database#allDocs is the standard approach for bulk data export. The generated row objects have additional _id and _rev keys that should be removed.

Nested objects must be flattened. The "Tutorial" includes an example of constructing a simple array.

function export_pouchdb_to_xlsx(db) {
  /* fetch all rows, including the underlying data */
  db.allDocs({include_docs: true}, function(err, doc) {

    /* pull the individual data rows */
    const aoo = doc.rows.map(r => {
      /* `rest` will include every field from `r` except for _id and _rev */
      const { _id, _rev, ...rest } = r;
      return rest;
    });

    /* generate worksheet */
    const ws = XLSX.utils.json_to_sheet(aoo);

    /* generate workbook and export */
    const wb = XLSX.utils.book_new();
    XLSX.utils.book_append_sheet(wb, ws, "Sheet1");
    XLSX.writeFile(wb, "SheetJSPouch.xlsx");
  });
}

Complete Example (click to show)

0. Download the "Working Version" from the Getting Started guide.

ZIP

The ZIP file should have MD5 checksum ac4da7cb0cade1be293ba222462f109c:

curl -LO https://github.com/nickcolley/getting-started-todo/archive/master.zip
md5sum master.zip || md5 master.zip
### the checksum will be printed

If the download is unavailable, a mirror is available at https://docs.sheetjs.com/pouchdb/master.zip

1. Unzip the master.zip file and enter the folder:

unzip master.zip
cd getting-started-todo-master

2. Edit index.html to reference the SheetJS library and add a button:

  <body>
<!-- highlight-start -->
    <script src="https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.full.min.js"></script>
    <button id="xport">Export!</button>
<!-- highlight-end -->
    <section id="todoapp">

3. Just before the end of app.js, add a click event listener:

  if (remoteCouch) {
    sync();
  }

  // highlight-start
  document.getElementById("xport").addEventListener("click", function() {
    db.allDocs({include_docs: true}, function(err, doc) {
      const aoo = doc.rows.map(r => {
        const { _id, _rev, ... rest } = r.doc;
        return rest;
      });
      const ws = XLSX.utils.json_to_sheet(aoo);
      const wb = XLSX.utils.book_new(); XLSX.utils.book_append_sheet(wb, ws, "Sheet1");
      XLSX.writeFile(wb, "SheetJSPouch.xlsx");
    });
  });
  // highlight-end
})();

4. Start a local web server:

npx http-server .

Access http://localhost:8080 from your browser. Add a few items and click the "Export!" button to generate a new file.