Prefilling through the form URL
You can prefill parent and child form fields using the form URL. This can be useful in a variety of use cases and can be achieved by appending the following to your form URL, where FieldName is the name of your Airtable field and Value is the value that you would like to prefill:
?prefill_FieldName=Value
You can also prefill multiple fields simultaneously, by appending each additional prefill with a & instead of the ? symbol.
An example URL could look like this:
https://web.miniextensions.com/yWo9TX3X8kH1bsKi2wok?prefill_Last%20Name=Doe&prefill_First%20Name=John
Prefilling hidden fields
To prefill hidden fields, enable Allow prefilling hidden fields from the Prefill section of the parent or child form. This setting allows you to prefill fields that are not part of your form's structure using the URL prefill parameter.
Prefilling new records created through a child form
When your form includes linked record fields and child forms, you can prefill records created in the linked table. To do this, simply add the prefill parameters in the Prefill New Records textbox located under the Prefill section of the child form. The syntax is the same as prefilling through the form URL.
Default field values
You can set default values for fields included in your form; they will populate the field when creating records or while editing if the field was left empty. Configure them in Default Value setting within the Standard Options section:
Automatically submit the form after prefill
Enabling this feature in the Prefill section will automatically submit the form after the prefill is applied, without requiring any further user interaction.
Troubleshooting:
1. Incorrect parameter syntax (most common)
The prefill function in the miniExtensions Form works in the same way as in the Airtable Form. In many cases, the issue is within the URL itself. If you're generating your URL using an Airtable formula, the ENCODE_URL_COMPONENT function in Airtable helps minimize improper syntax errors.
Common syntax issues:
Special characters are not encoded properly. A common issue is spaces not being encoded correctly. Please use %20 to represent any spaces in field names or data. (+ signs in field names will not work). Other special characters need to be encoded as well. You can find more information about this, as well as a list of common characters and their encoded value here.
The parameter ‘prefill_’ is not repeated for every field.
Field names are case-sensitive. Also, they have to match the actual field names in Airtable, not the custom titles you have on the form.
Commas in prefill values have to be wrapped in quotes. If the value itself has a comma, it has to be wrapped even if the comma is encoded as
%2C. This is because commas are used to separate different values, for example when linking multiple linked records to the same field or multiple options in a multi-select field.
Here's an example:
?prefill_Vendor=%22some%2C%20test%22,box
Value A:some, test
Value B:box
The prefill parameters are always the last part of the URL, so if you're editing a record and want to use prefills, the correct syntax would be:
https://web.miniextensions.com/extensionID/recordID?prefill_FieldX=y
Where extensionID is your extension ID, and recordID is the record ID of the record you want to edit. If you're using an Airtable formula to generate your URL, the syntax would look like this:
'https://web.miniextensions.com/extensionID/'& RECORD_ID() & '?prefill_FieldX=y'
💡 Note: You can see the encoded field names in the Prefill section.
2. Field Filters
Another reason you're having issues with your prefills could be the field's validation rules. Make sure that the value you're trying to prefill is 'selectable' if you try to add it to the form manually.
3. The field is read-only
If the field is set to read-only, you must enable the "Allow URL prefills" toggle to allow it to be prefilled.
4. Hidden fields
If the prefill fields are not part of the form, enable prefilling hidden fields.