This is a plugin that only has a peer dependency to piral-core. What piral-feeds brings to the table is a set of Pilet API extensions that can be used with piral or piral-core.

By default, these API extensions are not integrated in piral, so you'd need to add them to your Piral instance.

A standard scenario that needs to be covered by most applications is:

1. Don't load data in the beginning, but just when a component requiring this data should be shown
2. When the component should be shown read data from the backend - in the meantime showing a loading spinner
3. When data was received from backend actually show the component with the provided data
4. When data was updated (e.g., by having a WebSocket connection to the backend) the shown component updates its information, data
5. When data was manipulated (e.g., by submitting a PUT or POST to the backend) the data is updated, too and the shown component updates

Quite often, this simple scenario involves quite some code and ceremony to be reliable. The whole scenario (lazy load of data, update management on the data) is what call a "data feed" or short "feed" (not to confuse with Pilet Feed service, which is the service provisioning the pilets).

piral-feeds is an abstraction over the state management. The abstraction is exposed to be used by pilets with the pilet API. It allows creating a connector that returns a higher-order component capable of connecting any React (view) component to the data management.

Alternatives: Expose your own state management solution to the pilets such that they can work directly on it. Or leave it to pilets to manage lazy loading and state management on their own.

We also have a video for this plugin:

@youtube

The following functions are brought to the Pilet API.

Creates a new feed connector, which is an abstraction over a state container driven by the typical lifecycle of a data feed connection.

Returns a higher-order component for providing a data prop that reflects the current feed data.

::: summary: For pilet authors

You can use the createConnector function from the Pilet API to create a global container managed data feed inside the Piral instance.

There are two kind of calls. The simple variant just uses a callback to populate the data via a lazy loading mechanism.

Example use:

import { PiletApi } from '<name-of-piral-instance>';
import { Page } from './Page';

export function setup(piral: PiletApi) {
  const connect = createConnector(() => fetch('http://example.com').then(res => res.json()));
  piral.registerPage('/sample', connect(Page));
}

The most powerful variant declares three different sections:

1. initialize to declare how data should be loaded initially (e.g., by loading from some API) required
2. connect to define how updates of the data should be retrieved (e.g., via a WebSocket connection) optional
3. update to handle the patching of data (e.g., combining the current data with the data retrieved from a WebSocket connection) optional

If you specify connect we recommend to also define update.

Example use:

import { PiletApi } from '<name-of-piral-instance>';
import { Page } from './Page';

export function setup(piral) {
  const connect = createConnector({
    initialize() {
      return fetch('http://example.com').then(res => res.json());
    },
    connect(cb) {
      const ws = new WebSocket();
      ws.onmessage = e => cb(JSON.parse(e.data));
      return () => ws.close();
    },
    update(data, item) {
      return [...data, item];
    },
  });
  piral.registerPage('/sample', connect(({ data }) => <Page items={data} />));
}

Calling createConnector returns a higher-order component that injects a new prop called data into the component.

Furthermore two more options are available:

• immediately optionally avoids lazy loading and fetches the data immediately.
• reducers allows to extend the HOC with some actions triggering the provided reducer functions.

The latter can be used like in the following example:

import { PiletApi } from '<name-of-piral-instance>';

export function setup(piral: PiletApi) {
  const connect = piral.createConnector({
    initialize() {
      return Promise.resolve([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]);
    },
    update(data: Array<number>) {
      return data;
    },
    reducers: {
      shuffle(data) {
        return data.slice().sort(() => Math.random() - 0.5);
      },
    },
  });

  piral.registerPage(
    "/sample",
    connect(({ data }) => (
      <>
        <ul>
          {data.map((i) => (
            <li key={i}>{i}</li>
          ))}
        </ul>
        <button onClick={connect.shuffle}>Shuffle</button>
      </>
    ))
  );
}

:::

::: summary: For Piral instance developers

The provided library only brings API extensions for pilets to a Piral instance.

For the setup of the library itself you'll need to import createFeedsApi from the piral-feeds package.

import { createFeedsApi } from 'piral-feeds';

The integration looks like:

const instance = createInstance({
  // important part
  plugins: [createFeedsApi()],
  // ...
});

There are no options available.

:::

Piral is released using the MIT license. For more information see the license file.