Adding custom components

Sometimes we need a custom component to show in our forms, here's how.

First, make sure the dependency @webcomponents/custom-elements is installed in your implementation.

Add the line the following line to your scripts array in the angular.json of your implementation if it's not already there:


Also, add the following line to polyfills.ts in the src folder of your implementation if it's not already there:

import '@webcomponents/custom-elements/custom-elements.min';

Create a custom component, and a registration definition according to this guide:

Add your custom component to the declarations array in your AppModule.

Finally, it is necessary to add the registration function, and your component selector under COMPONENT_OPTIONS, both exported from your registration definition file, to the environment file of your implementation under the key customFormioComponentRegistrations like in this example:

// environment.ts


import {RATING_COMPONENT_OPTIONS, registerRatingComponent} from '@app/custom-formio-rating';


export const environment: Environment = {
  customFormioComponentRegistrations: [{
    selector: RATING_COMPONENT_OPTIONS.selector,
    function: registerRatingComponent

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