Customizing form field content based on URL query parameters like utm_source

[bsabalaskey]

I am wanting to modify the donation form based on URL query parameters like utm_source=campaign1. These would be two added text/graphics fields and modifying the donation ask array (multi-level donation amounts). The backend would have a custom post type (CPT) with Advanced Custom Fields to provide the input to the form (with the set of URL query to match, and the various data mentioned below). So I need to:

a) add two text/graphic (HTML) fields programmatically, and then populate them with the backend CPT values
b) use the multi-level donation amounts set in the backed with the CPT values, thus overriding the defaults set in the form.
c) do I just modify a form I create (presumably) or have to programatically create a whole new form?

Do your hooks and internal API support that? If yes, what hooks would those be?
Regards,
Bruce

[kjohnson]

Hey @bsabalaskey

GiveWP recently released a Fields API for dynamically adding fields to the donation forms. With that, you can hook into different template locations within the form and register a new custom field - GiveWP will take care of the rest.

See give/src/Framework/FieldsAPI/ for supported field types.
See give'src/Form/LegacyConsumer/TemplateHooks.php for supported form template locations.

// Add field(s) before payment gateways
add_action( 'give_fields_payment_mode_before_gateways', function( $collection ) {

    // Append a required text field with the name myTextField
    $collection->append(
        give_field( 'text', 'myTextField' )
            ->label( 'My Text Field' )
            ->required() // Could instead be marked as readOnly() (optional)
            ->helpText( __( 'This is my custom text field.' ) )
    );
});

[kjohnson]

Also, the donation levels are stored as a serialized array in the _give_donation_levels form meta, which can be programmatically altered as post meta.