Adding fields to all pieces

Apostrophe's schemas are a powerful way to add fields to any type of piece or page. But sometimes you'll have a field you want to add to every type of piece. Here's how to do that.

Adding a field to all pieces

As explained in the tutorials, the apostrophe-pieces module is a great way to create reusable content that appears all over the site — both on apostrophe-pieces-pages and in apostrophe-pieces-widgets.

We've seen how we can add fields to these by using the addFields option when configuring each module. But sometimes we want to add a field to every type of piece. We can do that by configuring the apostrophe-pieces module itself.

Any configuration we set for apostrophe-pieces becomes part of the configuration for all of the modules that extend it.

Our first idea might be to do this in app.js:

// lib/modules/apostrophe-pieces/index.js

// THIS WON'T WORK
modules: {
  'apostrophe-pieces': {
    addFields: [
      {
        type: 'string',
        name: 'author',
        label: 'Author'
      }
    ]
  }
}

This won't quite work. The reason is that the addFields option set for each subclass overrides it.

Another problem is that we wind up with "Pieces" on the admin bar. If we configure a module in app.js, Apostrophe assumes we want to use that module, not just extend it to create new modules.

So instead, we'll write a beforeConstruct function in lib/modules/apostrophe-pieces/index.js. The great thing about beforeConstruct is that it is called for the subclasses first. That means that by the time it is called for us, all the fields for the subclass are already in addFields. We can simply prepend our own:

// lib/modules/apostrophe-pieces/index.js

// THIS WILL WORK!
module.exports = {

  beforeConstruct: function(self, options) {
    options.addFields = [
      {
        type: 'string',
        name: 'author',
        label: 'Author'
      }
    ].concat(options.addFields || [])
  }
}

Making exceptions

If one of your subclasses of pieces doesn't need the author field, just use the removeFields option in that module.