Custom widgets

Creating new widget options in addition to the core widgets is crucial to getting the most from Apostrophe. Doing so allows developers to build the content structure a design requires while giving editors flexibility in how content will evolve over time.

Creating a widget type

Adding a new widget type involves creating a new module that extends the @apostrophecms/widget-type module. It also requires a template to render the editor input. The module configuration file will include a field schema with the appropriate fields.

We will use the example of a two column "layout widget." It is a fairly common and relatively simple use case that allows editors to visually align content in a row. This version of a layout widget consists of two areas next to one another. Each will allow either rich text and image widgets nested inside.

First create the module configuration file, extend the core widget type module, and add a widget label for editors. If you do not add a label, Apostrophe will attempt to generate one for the UI based on the module's name.

The module's name must end in -widget. It is a convention that supports core business logic around widgets and can help keep project code organized. This two-column widget is named two-column-widget.

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Generate the starter code using the official CLI with the command:

apos add widget two-column

// modules/two-column-widget/index.js
module.exports = {
  extend: '@apostrophecms/widget-type',
  options: {
    label: 'Two column'
  },
  // 👇 The widget type's field schema
  fields: {
    add: {
      // 👇 The first column area
      columnOne: {
        type: 'area',
        label: 'Column One',
        options: {
          widgets: {
            '@apostrophecms/rich-text': {},
            '@apostrophecms/image': {}
          }
        }
      },
      // 👇 The second column area
      columnTwo: {
        type: 'area',
        label: 'Column Two',
        options: {
          widgets: {
            '@apostrophecms/rich-text': {},
            '@apostrophecms/image': {}
          }
        }
      }
    }
  }
};

You may notice there is no group property to the field schema. The widget editing interface does not have field groups, so it is not necessary here.

You can then add this module to the app.js file to instantiate it.

// app.js
require('apostrophe')({
  shortName: 'my-website',
  modules: {
    'two-column-widget': {}
  }
});

Adding schema field placeholder content

Much like the core widgets, you can add placeholder content for many of the fields in your custom widgets. Within the widget options add placeholder: true. Then within individual fields add a placeholder property with a value appropriate to the type of schema field.

module.exports = {
  extend: '@apostrophecms/widget-type',
  options: {
    label: 'Custom Widget',
    icon: 'text-subject',
    placeholder: true,
    placeholderClass: 'my-custom-widget-placeholder'
  },
  fields: {
    add: {
      email: {
        type: 'email',
        placeholder: 'bob@email.com'
      },
      float: {
        type: 'float',
        placeholder: 0.05
      },
      integer: {
        type: 'integer',
        placeholder: 2
      },
      string: {
        type: 'string',
        placeholder: 'widget-with-placeholder placeholder'
      },
      url: {
        type: 'url',
        placeholder: 'https://example.com'
      }
    }
  }
};

This placeholder content will be present on the page when the widget is added. This content will never appear in the page preview. It will only appear on-page until you click Edit for that widget and save some real content. This data will also show up in the fields within the editor modal. The placeholder option can also be used to fill the editor modal fields with suggested content without also adding it to the page by setting it to false, but still adding placeholder content to each field.

INFO

If you set placeholder: true in the options and have either a date or time schema field, it will be populated with the current date/time on the page - not in the editor modal. Like the other fields, this content will not appear on the live page or in preview until you edit the widget and add actual content. It isn't possible to pass placeholder content into either of these fields.

The placeholderClass option can be used to add a class to the wrapper around the rendered display of the widget until it is edited for the first time.

Disabling the initial editor modal

Even when placeholder content is not needed, for some types of custom widgets, it may be useful to disable the automatic opening of the editor modal when it is first added to the page. This is similar to the behavior when adding placeholder content. The content is added to the page, but the Editor has to open the modal manually. For example, a widget to display a variable number of products set by default to five items. The Editor would only open the modal if they wanted to change this amount. The initialModal option is set to true by default, so to prevent initial modal opening, set the value to false.

INFO

Adding placeholder: true in the options for a widget automatically sets initialModal to false. This can not be overridden by passing a true value.

Widget templates

Before using the new widget type, it needs a template file, widget.html, in the module's views directory. A simple template for the two column widget might look like:

{# modules/two-column-widget/views/widget.html #}
<section class="two-col">
  <div class="two-col__column">
    {% area data.widget, 'columnOne' %}
  </div>
  <div class="two-col__column">
    {% area data.widget, 'columnTwo' %}
  </div>
</section>

Widget field values are available on data.widget in templates. Context options passed in are available on data.contextOptions.

INFO

Here are some two-column styles for people following along.

/* modules/two-column-widget/ui/src/index.scss */
.two-col {
  display: flex;
  flex-flow: row wrap;
  width: 100%;
}

.two-col__column {
  display: flex;
  flex-direction: column;
  flex: 1;
}

Client-side JavaScript for widgets

When adding client-side JavaScript for widget interaction, add a widget "player" to contain that code. The player will run only when the widget is used. It will also run when the editable area of the page is refreshed during editing.

We can use the example of a basic collapsible section widget, collapse-widget (also known as an "accordion" or "disclosure" widget). It will hide detail text until a user clicks the header/button.

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When using the official CLI to create a widget type, include widget player starter code with the --player option.

apos add widget collapse --player

Example collapsible widget code

Module configuration

// modules/collapse-widget/index.js
module.exports = {
  extend: '@apostrophecms/widget-type',
  options: {
    label: 'Collapsible section'
  },
  fields: {
    add: {
      heading: {
        type: 'string',
        required: true
      },
      detail: {
        type: 'string',
        required: true,
        textarea: true
      }
    }
  }
};

Module template

{# modules/collapse-widget/views/widget.html #}
<section data-collapser class="collapser">
  <h2>
    <button data-collapser-button aria-expanded="false">
      {{ data.widget.heading }}
    </button>
  </h2>
  <div hidden data-collapser-detail>
    {# `nlbr` and `safe` are core Nunjucks tag filters #}
    {{ data.widget.detail | nlbr | safe }}
  </div>
</section>

Module styles (see front end assets guide)

.collapser__detail {
  display: none;

  &.is-active {
    display: block;
  }
}

Widget player code can be added in any module's ui/src/index.js file, or a file imported by it. In this example it would be in modules/collapse-widget/ui/src/index.js.

The player code is added to an object of widget players, apos.util.widgetPlayers using the widget's name, excluding the -widget suffix. It is an object with two properties:

Property	Description
selector	A string selector for the player to find the widget as you would use in document.querySelector.
player	A function that takes the matching widget DOM element as an argument.

// modules/collapse-widget/ui/src/index.js
export default () => {
  apos.util.widgetPlayers.collapser = {
    selector: '[data-collapser]',
    player: function (el) {
      // ...
    }
  };
};

With some code to manage showing and hiding the detail, it would look like:

export default () => {
  apos.util.widgetPlayers.accordion = {
    selector: '[data-collapser]',
    player: function (el) {
      // Find our button
      const btn = el.querySelector('[data-collapser-button]');
      // Find our hidden text
      const target = el.querySelector('[data-collapser-detail]');

      btn.onclick = () => {
        const expanded = btn.getAttribute('aria-expanded') === 'true';
        // Update the button's aria attribute
        btn.setAttribute('aria-expanded', !expanded);
        // Update the `hidden` attribute on the detail
        target.hidden = expanded;
      };
    }
  };
};

Credit goes to Heydon Pickering for the accessible collapsible example.

Using widget data in players

Widget players do not have direct access to any widget data. If we want to use widget data in the player, we need to pass it in.

Template files on the other hand, do have access to widget data (they are rendered on the server). One good way to use data in a widget player is to insert it as a data attribute value in the template. The player can then look for that data attribute.

For example, we could change our collapse widget to include a color field value:

{# modules/collapse-widget/views/widget.html #}
<section data-collapser data-color="{{ data.widget.color }}" class="collapser">
  {# The rest of the code is the same... #}
</section>

We've added the data-color attribute to the widget wrapper with our color data. Then in the player code we could get the value with the wrapper element's dataset property.

export default () => {
  apos.util.widgetPlayers.accordion = {
    selector: '[data-collapser]',
    player: function (el) {
      const color = el.dataset.color || 'purple'
      // The rest of the code is the same...
    }
  };
};

The player does have access to the widget's wrapping element, so we use el.dataset.color to access the color data we stored on data-color.

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We can pass a string, number, or boolean value with a data attribute using the method shown above. If the value we need to use in the widget player is an array or object, it will need to become a properly escaped string first. Use the jsonAttribute template filter to do this.

<div data-config="{{ data.piece.someObjectOrArray | jsonAttribute }}"></div>

The value will be converted to a JSON string and escaped. The original value can retrieved in the player with JSON.parse.