TriggerPipelineOnCallback

The TriggerPipelineOnCallback pipeline trigger is an advanced component used internally to implement the nested pipelines.

To make it easier to explain how it works, let us take a look at how NestedPipeline is implemented in the package.

import React from 'react';
import useWillPipe from '../hooks/use-will-pipe';
import Pipeline from './Pipeline';
import TriggerPipelineOnCallback from '../triggers/TriggerPipelineOnCallback';

export default function NestedPipeline({ children }) {
  const callbackRef = React.useRef(null);

  const updateCallbackRef = (callback) => {
    callbackRef.current = callback;
  };

  useWillPipe(() => {
    if (callbackRef.current && typeof callbackRef.current === 'function') {
      callbackRef.current();
    }
  });

  return (
    <Pipeline>
      <TriggerPipelineOnCallback callback={updateCallbackRef} />
      {children}
    </Pipeline>
  );
}

The base functionality is this:

A callback function provided to the trigger as the callback prop will be executed on mount (in reality when a change to the pipeline context or the provided callback is changed).

In the above example, this is the updateCallbackRef function. It will get passed a new function when called. This passed function is the one we actually have to execute in order to trigger the pipeline.

In this case, we store it internally in a React ref hook for later use. We are using a ref instead of for instance a state to avoid rerendering our entire component. If we were using a state, we would also have to add the state variable as a dependency to the useWillPipe hook.

Whenever our component is then piping, it will call the function and trigger its child pipeline.

Instead of using useWillPipe as in our example, it could also be by any other event in the component.