Returning a promise in a Redux thunk with typescript

Question

I am getting this typescript error: Property 'then' does not exist on type 'ThunkAction<Promise<boolean>, IinitialState, undefined, any>'.

Please help!

How I have configured my store and included the type:

    return createStore(
      rootReducer,
      intialState,
      require('redux-devtools-extension').composeWithDevTools(
        applyMiddleware(
          thunk as ThunkMiddleware<IinitialState, any>,
          require('redux-immutable-state-invariant').default()
        )
      )

Action Creator:

type ThunkResult<R> = ThunkAction<R, IinitialState, undefined, any>;

export function anotherThunkAction(): ThunkResult<Promise<boolean>> {
  return (dispatch, getState) => {
    return Promise.resolve(true);
  }
}

then in my component I have a prop interface:

interface IProps {
  anotherThunkAction: typeof anotherThunkAction;
}

Then:

  componentWillMount() {
    this.props.anotherThunkAction().then(() => {console.log('hello world')})
  }

Connect where I am using react-i18next as well:

export default translate('manageInventory')(
  connect(
    mapStateToProps,
    {
      anotherThunkAction
    }
  )(ManageInventory)
);

Answer 1

I don't think you're dispatching things properly... you are calling your action without passing it through the store.

If you call the action directly, you'll get back :

ThunkAction<Promise<boolean>, IinitialState, undefined, any>

Which as tsc is telling you, doesn't have a then function. When you run something through dispatch it turns ThunkResult<R> into R

You haven't shown how you connect your component to the store - but I think this is where the problem lies. Here is a sample:

type MyThunkDispatch = ThunkDispatch<IinitialState, undefined, any>

const mapDispatchToProps = (dispatch: MyThunkDispatch) => ({
  anotherThunkAction: () => dispatch(anotherThunkAction())
})

connect(null, mapDispatchToProps)(MyComponent)

This will add anotherThunkAction to props and you can call it and it'll call into your action properly and return the promise.