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Autofill API (Beta)

Describes the Autofill API, used to prefill an element with a value from an external system.



Optimizely Forms is only supported by MVC-based websites and HTML5-compliant browsers.

This is a Beta feature, which means that it is still in development.

In Forms.Core, DataElementBlockBase uses Autofill to prefill an element with a value from an external system.

AutofillService finds AutofillProvider based on the MappingTable as input, and gets suggestions from them. For example, if formElement is set to Email, AutofillProvider checks the CRM system and selects Email data from the ContactTables and returns a suggestion.



Render <datalist> as suggestions for a visitor that views a form in View mode.

An element rendered in View mode can have a pre-selected value that is determined by the following input (by priority):

  • Manual input from a user
    When a visitor selects a value, it is retained in the element.

  • External system autofill
    If a form is connected to a Marketing Automation (MA) system, the MA system can provide information about the visitor to prefill into the element value as the selected value. The first suggestion is set automatically in the input as a predefined value.

  • Predefined value
    An editor sets it in edit view.

  • In the demo project
    DemoSystem acts like both IExternalSystem and IAutofillProvider.