---
title: Spreadsheets in Dropbox
sidebar_label: Dropbox
pagination_prev: demos/local/index
pagination_next: demos/extensions/index
---

<head>
  <script type="text/javascript" src="https://www.dropbox.com/static/api/2/dropins.js" id="dropboxjs" data-app-key="6msofx0wc1zd7da"></script>
</head>

[Dropbox](https://www.dropbox.com/) is a file hosting service that offers APIs
for programmatic file access.

[SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing
data from spreadsheets.

This demo uses SheetJS to read and write spreadsheets stored on Dropbox. We'll
explore two Dropbox API workflows:

- A "Chooser"[^1] application allows users to select files from their Dropbox
accounts. This demo will fetch and parse the selected file.

- A "Saver"[^2] application allows users to save a generated spreadsheet to
their Dropbox account. This demo will generate a XLS workbook using SheetJS.

## Integration Details

"Dropbox Apps" are the standard way to interact with the service.  The
["Dropbox App"](#dropbox-app) section describes how this demo was configured.

:::info pass

The Dropbox API script is loaded in this page with

```html
<script type="text/javascript" src="https://www.dropbox.com/static/api/2/dropins.js" id="dropboxjs" data-app-key="6msofx0wc1zd7da"></script>
```

The `data-app-key` used in this demo is a "Development" key associated with the
`localhost` and `docs.sheetjs.com` domains.  Dropbox API does not require
"Production" approval for the Chooser or Saver.

:::

The live demos require a Dropbox account.

### Reading Files

"Chooser" is a small library that lets users select a file from their account.
`Dropbox.createChooseButton` is a function that accepts an options argument and
returns a DOM element that should be added to the page:

```js
var button = Dropbox.createChooseButton({
  /* ... options described below ... */
});
document.appendChild(button);
```

The following options must be set:

- `multiselect: false` ensures only one file can be selected
- `folderselect: false` limits selection to real files
- `linkType: "direct"` ensures the link points to a raw file
- `success` method is called when the user selects a file

The following options are optional:

- `extensions: ['.xlsx', '.xls']` limits the file types for selection

#### Chooser Callback

The `success` callback method receives an array of File objects even if only one
file is selected. This file object has the following properties:

- `name` is the name of the selected file
- `link` is a temporary URL that can be fetched

This demo fetches the link using the `fetch` API, parses the raw data using the
SheetJS `read` function[^3] and generates a HTML table using `sheet_to_html`[^4]

```js
async(files) => {
  /* get file entry -- note that dropbox API always passes an array */
  var file = files[0];
  console.log(`Selected ${file.name} ID=${file.id}`);

  /* fetch file and parse */
  var wb = XLSX.read(await (await fetch(file.link)).arrayBuffer());

  /* convert first sheet to HTML table and add to page */
  var html = XLSX.utils.sheet_to_html(wb.Sheets[wb.SheetNames[0]]);
  console.log(html);
}
```

#### Chooser Live Demo

:::caution pass

If the live demo shows a message

```
ReferenceError: Dropbox is not defined
```

please refresh the page.  This is a known bug in the documentation generator.

:::

```jsx live
function SheetJSChoisissez() {
  const [msg, setMsg] = React.useState("Press the button to show a Chooser");
  const btn = useRef(), tbl = useRef();
  React.useEffect(() => {
    if(typeof Dropbox == "undefined") return setMsg("Dropbox is not defined");
    /* create button */
    var button = Dropbox.createChooseButton({
      /* required settings */
      multiselect: false,
      folderselect: false,
      linkType: "direct",
      /* optional settings */
      extensions: ['.xlsx', '.xls', '.numbers'], // list of extensions

      /* event handlers */
      cancel: () => setMsg("User Canceled Selection!"),
      success: async(files) => {
        /* get file entry -- note that dropbox API always passes an array */
        var file = files[0];
        setMsg(`Selected ${file.name} ID=${file.id}`);

        /* fetch file and parse */
        var wb = XLSX.read(await (await fetch(file.link)).arrayBuffer());

        /* convert first sheet to HTML table and add to page */
        tbl.current.innerHTML = XLSX.utils.sheet_to_html(wb.Sheets[wb.SheetNames[0]]);
      }
    });
    /* add button to page */
    btn.current.appendChild(button);
  }, []);
  return ( <><b>{msg}</b><br/><div ref={btn}/><div ref={tbl}/></> );
}
```

### Writing Files

"Saver" is a small library that lets users save files to their account.
`Dropbox.createSaveButton` is a function that accepts three arguments and
returns a DOM element that should be added to the page:

```js
var button = Dropbox.createSaveButton(url, filename, options);
/* add button to page */
btn.current.appendChild(button);
```

`filename` will be the recommended filename in the Save window.

The options object supports two callbacks: `success` (if the save succeeded) and
`cancel` (if the user cancels without saving).

#### URL

:::caution pass

The Dropbox API was not designed for writing files that are created in the web
browser.  The Data URI approach is a neat workaround but should not be used in
production for larger files.  It is better to create the files in the server
using NodeJS and generate a proper URL for Dropbox to fetch.

:::

The Dropbox API is designed to fetch data from a user-specified URL. Files are
not included in the request!

The SheetJS workaround involves the Data URI scheme[^5]. The main steps are:

1) Write a workbook using the SheetJS `write`[^6] method. The `type: "base64"`
option instructs the method to return a Base64-encoded string.

```js
/* write XLS workbook (Base64 string) */
const b64 = XLSX.write(workbook, { type: "base64", bookType: "xls" });
```

2) Construct a Data URL by prepending the `data` header:

```js
/* create data URI */
const url = "data:application/vnd.ms-excel;base64," + b64;
```

3) Create a button and add it to the page:

```js
/* create save button using the concise function call */
var button = Dropbox.createSaveButton( url, "SheetJSDropbox.xls", {
  success: () => setMsg("File saved successfully!"),
  cancel: () => setMsg("User Canceled Selection!"),
});
document.appendChild(button);
```

:::info pass

The file must be written before the Save button is created.

:::

#### Saver Live Demo

This demo seeds data by fetching a file and writing to HTML table. The generated
table is scraped to create a new workbook that is written to XLS.

:::caution pass

If the live demo shows a message

```
ReferenceError: Dropbox is not defined
```

please refresh the page.  This is a known bug in the documentation generator.

:::

```jsx live
function SheetJSEnregistrez() {
  const [msg, setMsg] = React.useState("Press the button to write XLS file");
  const btn = useRef(), tbl = useRef();
  React.useEffect(() => { (async() => {
    if(typeof Dropbox == "undefined") return setMsg("Dropbox is not defined");
    /* fetch data and write table (sample data) */
    const f = await(await fetch("https://sheetjs.com/pres.xlsx")).arrayBuffer();
    const wb = XLSX.read(f);
    tbl.current.innerHTML = XLSX.utils.sheet_to_html(wb.Sheets[wb.SheetNames[0]]);

    /* create workbook from table */
    const table = tbl.current.getElementsByTagName("TABLE")[0];
    const new_wb = XLSX.utils.table_to_book(table);

    /* write XLS workbook (Base64 string) */
    const b64 = XLSX.write(new_wb, { type: "base64", bookType: "xls" });

    /* create data URI */
    const url = "data:application/vnd.ms-excel;base64," + b64;

    /* create save button using the concise function call */
    var button = Dropbox.createSaveButton( url, "SheetJSDropbox.xls", {
      success: () => setMsg("File saved successfully!"),
      cancel: () => setMsg("User Canceled Selection!"),
    });
    /* add button to page */
    btn.current.appendChild(button);
  })(); }, []);
  return ( <><b>{msg}</b><br/><div ref={btn}/><div ref={tbl}/></> );
}
```

## Dropbox App

:::note Tested Deployments

This demo was last tested on 2023 November 30.

:::

This demo requires a "Dropbox app":

0) Create a Dropbox account and verify the associated email address. This demo
has been tested with a free Dropbox Basic plan account. The app installation
step can be safely skipped.

1) Create a Dropbox app in the Developer panel.

Click the `᎒᎒᎒` icon > App Center. In the next page, click "Build an App". In
the next page, click "Create Apps".

In the App creation wizard, select the following options:

- "Choose an API": "Scoped access"
- "Choose the type of access you need": "Full Dropbox"
- "Name": (enter any name) "SheetJS Docs"

:::caution pass

The Dropbox API Terms and Conditions should be reviewed before acceptance.

:::

Click "Create App" to create the app.

2) Configure the Dropbox app in the Developer tools.

The following permissions should be selected in the "Permissions" tab

- `files.metadata.write` (View and edit information about your Dropbox files and folders)
- `files.metadata.read` (View information about your Dropbox files and folders)
- `files.content.write` (Edit content of your Dropbox files and folders)
- `files.content.read` (View content of your Dropbox files and folders)

In the settings tab, under "Chooser / Saver / Embedder domains", the desired
public domains should be added. `localhost` must also be added for development
use (it is not automatically enabled).

For public use, select "Enable Additional Users".

3) Copy the "App key" and add it to the `data-app-key` attribute of the Dropbox
integration script reference.

[^1]: See ["Chooser"](https://www.dropbox.com/developers/chooser) in the Dropbox Developers Documentation
[^2]: See ["Saver"](https://www.dropbox.com/developers/saver) in the Dropbox Developers Documentation
[^3]: See [`read` in "Reading Files"](/docs/api/parse-options)
[^4]: See [`sheet_to_html` in "Utilities"](/docs/api/utilities/html#html-table-output)
[^5]: See ["Data URLs"](https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs) in the "MDN web docs"
[^6]: See [`writeFile` in "Writing Files"](/docs/api/write-options)