How to alter array within an object of a state using redux toolkit

Question

How to alter likes array within a post element of the state using redux toolkit in reactjs?

Data:

postLists: [
      {
        _id: '61978be44ad9dcef6ea24bb1',
        title: 'Welcome Nuxt Js',
        category: 'Nuxt JS',
        isLiked: false,
        isDisLiked: false,
        numViews: 1,
        likes: [],
        disLikes: [],
        user: '619094623616b44ff3eb80f8',
        description: 'Welcome to new web development framework called Nuxt JS. It is built on top of Node JS.',
        image: '',
        createdAt: '2021-11-19T11:35:00.976Z',
        updatedAt: '2022-02-01T07:12:33.269Z',
        __v: 0,
        likesCount: 0,
        commentsCount: 2,
        id: '61978be44ad9dcef6ea24bb1'
      },
]

I tried to add likes like below but it isn't updating the likes array:

    //Likes
    builder.addCase(toggleAddLikesToPost.pending, (state, action) => {
      state.loading = true;
    });
    builder.addCase(toggleAddLikesToPost.fulfilled, (state, action) => {
      console.log('action', action);
      // state.likes = action?.payload;
      state.posts.find((post) =>
        post._id === action.meta.arg[0]
          ? { ...post, likes: [...action.payload.user] }
          : post
      );

      console.log('state', state.posts);

      state.loading = false;
      state.appErr = undefined;
      state.serverErr = undefined;
    });
    builder.addCase(toggleAddLikesToPost.rejected, (state, action) => {
      state.loading = false;
      state.appErr = action?.payload?.message;
      state.serverErr = action?.error?.message;
    });

Answer 1

state.posts = state.posts
  .map((post) => post._id === action.meta.arg[0]
      ? { ...post, likes: [...action.payload.user] } : post
  );

Answer 2

const found = state.posts.find((post) => post._id === action.meta.arg[0])

if (found) {
  // modify it here - completely replace it with `user`:
  found.likes = action.payload.user;
  // or add it at the end:
  found.likes.push(action.payload.user)
}