This documentation is for the old Kea 1.0. To see the latest docs for 2.0, click here!

NB! See the plugins API page for a list of everything that plugins can do.

Requests plugin

In this guide we will write a simple plugin called "requests" that takes as input an action and creates 3 actions for different states of this action. Something like this:

// this input:
kea({
  requests: () => ({
    fetchArticle: (id) => api.fetchArticle(id)
    fetchComments: (id) => api.fetchComments(id),
    postComment: (id, comment) => api.postComment(id, comment)
  })
})

// will be converted to this output:
kea({
  actions: () => ({
    fetchArticle: (id) => ({ id }),
    fetchArticleSuccess: (request, response) => ({ request, response }),
    fetchArticleFailure: (error) => ({ error })

    fetchComments: (id) => ({ id }),
    fetchCommentsSuccess: (request, response) => ({ request, response }),
    fetchCommentsFailure: (error) => ({ error })

    postComment: (id, comment) => ({ id, comment }),
    postCommentSuccess: (request, response) => ({ request, response }),
    postCommentFailure: (error) => ({ error })
  })
})

The first step in authoring a plugin is to create a blank plugin and add it to the plugins array in resetContext.

Here's a sample skeleton structure for a plugin, extracted from the code on the plugins API page. See that page for all that you can do with plugins.

const requestsPlugin = (/* { options } */) => ({
  // Required: name of the plugin
  name: 'requests'

  // default values for output in logic,
  // also used to register keys that the plugin exports on the logic
  defaults: () => ({
  }),

  // when are the build steps run
  // (skip this and they are appended to the end)
  buildOrder: {
  },

  // steps that are performed when building the logic
  buildSteps: {
  }

  // various other events that the plugin can hook into
  events: {
  }
})


// later:
resetContext({
  createStore: true,
  plugins: [ requestsPlugin ]
})

This time we're only interested in the afterLogic event. We will take the input from our "requests" object and extend the logic with the actions that we generate from it.

const requestsPlugin = (/* { options } */) => ({
  name: 'requests'

  events: {
    afterLogic (logic, input) {
      // skip if there are no requests in the input
      if (!input.requests) {
        return
      }

      // run the requests function with the already created logic as an input,
      // so it can do ({ actions, ... }) => ({ ... })
      const requests = input.requests(logic)

      // TODO: convert requests into newActions
      let newActions = {}

      // extend the logic with these actions
      logic.extend({
        actions: () => newActions
      })
    }
  }
})

TODO This documentation is still a work in progress... but I hope you can imagine what happens next :)