ngrx update array of objects - map does not exist on state

Question

Trying to update an array of objects via ngrx-reducer I found some examples in the web (e.g. https://blog.strongbrew.io/Redux-best-practices/)

Some of them try to perform state.map, but I get an error "property 'map' does not exist on type 'state'".

In an array of objects, I would like to update the property languageStrg of one of the objects. Here is my code:

export function langsReducer(state = initialState, action: LangsActions): State {
    switch (action.type) {
        case ActionTypes.SETLANG: {
            return state.map(obj =>
                obj.languagePurpose === action.payload.languagePurpose ?
                {...state, languageStrg: action.payload.languageStrg} :
                obj);
            }
}

How could I rewrite the code so that the update works?

Answer 1

In your case it will be

export function langsReducer(state = initialState, action: LangsActions): State {
    switch (action.type) {
        case ActionTypes.SETLANG: {
            return {
                ...state,
                languages: state.languages.map(obj =>
                    obj.languagePurpose === action.payload.languagePurpose
                        ? {...obj, languageStrg: action.payload.languageStrg}
                        : obj
                    )
            };
        }
        default:
            return state;
    }
}