# Pre-fill data in a form

This will only work with **custom fields** in your form (not core fields or action-only fields)

- If the field name has spaces in it, then you need to use %20 in the URL for each space.
- If the URL is case sensitive, e.g. use Region, not region if you were to pre-fill that particular field

A current example of this is the volunteer form for Upgrade Democracy and here is a URL that allows for the first question to be auto-filled.

The custom field is `ASUD_PrefRole` and the url mechanism is

`source=ASUD_PrefRole=Steward`

Here is the full URL (with an extra source parameter showing the person is signing up from the Rebel Toolkit):

`https://actionnetwork.org/forms/upgrade-democracy-crew-signup?source=RTUDCrew&ASUD_PrefRole=Steward&`

You can see this and various other pre-selected choices on the Upgrade Democracy [volunteering page](https://rebeltoolkit.extinctionrebellion.uk/books/upgrade-democracy/page/volunteer-roles-at-upgrade-democracy)

[More information on custom fields is here](https://rebeltoolkit.extinctionrebellion.uk/link/655#bkmrk-page-title)