extract-object-from-form-data

Utility for turning values from FormData into a JavaScript object.

Why?

The initial motivation for this utility is to handle form submissions in Remix/React Router v7. Instead of form submissions coming in the form of application/json, Remix form submissions are sent as FormData. There are lots of reasons why this method of form submission is great, but pulling the data out of the FormData object is not one of them, especially with large forms:

const firstName = formData.get('firstName');
const lastName = formData.get('lastName');
const email = formData.get('email');

// etc. etc. etc.

const lastValue = formData.get('lastValue');

Installation

$ npm install extract-object-from-form-data

Importing

import { extractObjectFromFormData } from 'extract-object-from-form-data';

Usage

Extracting values from a simple form (like the example above):

<input type="text" name="firstName" />
<input type="text" name="lastName" />
<input type="text" name="email" />
<!--  some other inputs here-->
<input type="text" name="lastValue" />

// When handling the form submission
const formData = await request.formData();
const { firstName, lastName, email, lastValue, ...rest } = extractObjectFromFormData(formData);

Nested data

You can create nested data by giving your form inputs the right names:

<input type="text" name="id" />
<input type="text" name="name.first" />
<input type="text" name="name.last" />
<input type="text" name="contact.email" />
<!--  some other inputs here-->
<input type="text" name="lastValue" />

// When handling the form submission
const formData = await request.formData();
const userData = extractObjectFromFormData(formData);

/**
  Example output
{
  id: 'user-123',
  name: {
    first: 'John',
    last: 'Lennon'
  },
  contact: {
    email: 'john@example.com'
  },
  lastValue: 'the end'
}
*/

Lists

You can create lists of values:

<input type="text" name="id" />
<input type="text" name="names[0]" />
<input type="text" name="name[1]" />
<input type="text" name="contact[0].email" />
<input type="text" name="contact[0].phone" />
<!--  some other inputs here-->
<input type="text" name="lastValue" />

// When handling the form submission
const formData = await request.formData();
const userData = extractObjectFromFormData(formData);

/**
  Example output
{
  id: 'user-123',
  name: [ 'John', 'Lennon' ],
  contact: [{
    email: 'john@example.com',
    phone: '555-555-1234'
  }],
  lastValue: 'the end'
}
*/

Booleans (checkboxes)

Checkboxes are difficult, because if they checkbox is not checked, then the name/value pair is not present in the FormData. To make your checkboxes always show up in the output of extractObjectFromFormData, you can add a type="hidden" Input along with the checkbox. It needs to have the same name, plus .isCheckbox, then set the value of the checkbox input to isChecked Please see the example below:

<input type="checkbox" name="likesTheBeatles" value="isChecked" />
<input type="hidden" name="likesTheBeatles.isCheckbox" />

// When handling the form submission
const formData = await request.formData();
const userData = extractObjectFromFormData(formData);

/**
  Example output if the checkbox is checked
{
  likesTheBeatles: true,
}
*/

/**

  Example output if the checkbox is not checked
{
  likesTheBeatles: false,
}
*/

Contributing

PRs, bug reports, and feature requests are welcome. To get started contributing, check out the GitHub repo, then:

$ npm install

To run tests (and typecheck and lint)

$ npm run typecheck && npm run lint && npm run test