NgRx Reducer - Make it array in the new syntax

Question

How i make an array in the new reducer?

With old syntax id do this:

    const initialState: Comment = {
      fullName: null,
      comment: null
    };

    export function commentReducer(state: Comment[] = [], action: CommentAction.Action) {
      switch (action.type) {
        case CommentAction.ADD_COMMENT:
          return [...state, action.payload];
        case CommentAction.REMOVE_COMMENT:
          state.splice(action.payload, 1);
          return state;
          default:
            return state;
      }

    }

Now in new reducer i do this but its not array

    export const initialState: Comment = {
      fullName: null,
      comment: 'null'
    };

    const commentReducer = createReducer(
      initialState,
      on(CommentAction.addcomment, (state, { fullName, comment }) => ({ fullName, comment }))
    );


    export function reducer(state: Comment | undefined, action: Action) {
      return commentReducer(state, action);
    }

I try to dispatch but its not add to array it just replace it. What i do wrong?

Answer 1

firstly: your initialState should be an array, secodly: just return an array

export const initialStat: Comment[] = [];

const commentReducer = createReducer(
      initialState,
      on(CommentAction.addcomment, (state, { fullName, comment }) => [...state, { fullName, comment }])
    );

  export function reducer(state: Comment[], action: Action) {
      return commentReducer(state, action);
    }

I also fixed types Comment to Comment[] where it was required