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An opinionated approach to type actions and their payload in Redux with statically type checking in Typescript.

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Redux Typed Actions

An opinionated approach to type actions and their payload in Redux with statically type checking in Typescript. This approach removes the most possible boilerplate of your actions & their creators in React and any other frameworks.

Installation

Let's get started by installing it from npm repository

$ npm install --save-dev redux-typed-actions

or from yarn repository

$ yarn add --dev redux-typed-actions

Usage

Let's do a quick example to see how this approach can improve type checking of redux actions

  1. You have an ItemX interface:
    feature-x.types.ts

    export interface ItemX {
      title: string;
    }
  2. First we define our actions:
    feature-x.actions.ts

    import { defineAction, defineScenarioAction, defineSymbolAction } from 'redux-typed-actions';
    import { ItemX } from './feature-x.types';
    
    // For this action we will have number as our payload
    export const FeatureXAddTicketAction = defineAction<number>('[Feature X] Add Ticket');
    
    /**
     *  This action is special, it's called a scenario-like action
     *  It notifies the system with status of a process covering from start to end.
     *  You can get Start/Success/Failure/Cancel from this action generator/creator
     *  There are 4 types that belong respectively to Start/Success/Failure/Cancel
     *  Note: The default type for payload of success and failure is
     *  string so you can skip them like `defineScenarioAction('MyActionName')`
     */
    export const FeatureXLoadAction = defineScenarioAction<never, ItemX[], string>('[Feature X] Load');
    
    // Let's have a symbol action just for fun
    export const FeatureXDummySymbolAction = defineSymbolAction<ItemX[]>('[Feature X] Dummy Started');

    Note: You can setup your own suffix for Start/Success/Failure/Cancel of scenario actions as following example:

    import { factory } from 'redux-typed-actions';
    
    // You must set them before defining actions
    factory.setSuffixes({
      start: '_REQUEST',
      cancel: '_CANCEL',
      success: '_SUCCESS',
      failure: '_FAILURE',
    });
  3. Now we dispatch our actions:
    feature-x.component.ts

    import { ItemX } from './feature-x.types';
    import { FeatureXAddTicketAction, FeatureXLoadAction } from '../feature-x.actions';
    ...
    
    // React Redux solution to replace action creators:
    // Let's define our component's state
    interface FeatureXProps {
      ...
      addTicket: typeof FeatureXAddTicketAction.strictGet; // StrictGet makes the payload mandatory
    }
    
    ...
    class FeatureX extends React.Component<FeatureXProps> {
      ...
      addTicket = () => this.props.addTicket(1) // <- Static type checking
    
      render() {
        return (<button onClick={this.addTicket}>Add one ticket</button>); // />
      }
    }
    
    // Let's hook the action to redux, and we're done
    export default connect(undefined, { addTicket: FeatureXAddTicketAction.strictGet })(FeatureX);
    
    
    // All Typescript frameworks:
    // Dispatching a simple action
    store.dispatch(FeatureXAddTicketAction.get(100));
    
    // Let's start our scenario by dispatching our action
    store.dispatch(FeatureXLoadAction.get());
    
    // Now we dispatch the success action
    const payload: ItemX[] = [{ title: 'item 1' }, { title: 'item 2' }];
    dispatch(FeatureXLoadAction.success.get(payload));
    
    // or simply a failure
    dispatch(FeatureXLoadAction.failure.get('It failed because...'));
  4. Now let's take a look at our reducers to see how we can type check the payloads:
    feature-x.reducers.ts

    import { PlainAction } from 'redux-typed-actions';
    import { ItemX } from './feature-x.types';
    import { FeatureXLoadAction } from '../feature-x.actions';
    
    export interface ItemXState {
      items: ItemX[];
      loading: boolean;
    }
    
    export function reducer(state: ItemXState = InitialState, action: PlainAction): ItemXState {
      if (FeatureXLoadAction.is(action)) {
        // Within this branch our action variable has the right typings
        return {
          ...state,
          loading: true,
        };
    
      } else if (FeatureXLoadAction.success.is(action)) {
        return {
          ...state,
          loading: false,
          items: action.payload, // <- Here we are checking types strongly
        };
    
      } else {
        return state;
      }
    }
  5. If you're fan of redux-observables then this part is for you:
    feature-x.epics.ts

    (action$, store) => action$
       .ofType(FeatureXLoadAction.type)
       .map(action => FeatureXLoadAction.cast(action)) // <- from here we will have all the typings right :)
       .switchMap(action => Service()
           .map(value => FeatureXLoadAction.success.get(repos))
           .catch(() => Observable.of(FeatureXLoadAction.failure.get('Oops something went wrong!'))));
  6. That's it

Take a look at React or Angular examples for a closer look.

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An opinionated approach to type actions and their payload in Redux with statically type checking in Typescript.

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