NGRX Reducer Set array to Empty inside in the Object

Question

I have Store object structure as follows

{
   "fooObject":[
      {
         "id":1,
         "somefield":"bla bla",
         "orderArray":[
            {
               "id":1,
               "somefield":"a"
            },
            {
               "id":2,
               "somefield":"b"
            },
            {
               "id":3,
               "somefield":"c"
            }
         ]
      }          
   ]
}

I need to make the orderArray empty on the NGRX reducer. and only need to change that array. I attempted to following to obtain my desired behavior but was unsuccessful.I tried using the Map method as well, but it failed.

on(ProductionLineAction.successSetInitialStateScheduledOrderLine, (state, action) => {
    return {
      ...state,
      fooObject: [
        ...state.productionLinesDisplayDetails,
        {
          orderArray: action.scheduledOrders
        }
      ]
    }
  }),

Answer 1

The reducer will have frozen all the objects in the state tree so you'll have to create a new array with a new copy of the data.

on(ProductionLineAction.successSetInitialStateScheduledOrderLine, (state, action) => {
    return {
      ...state,
      fooObject: state.fooObject.map(obj => ({
      ...obj, // copy all other old values in each fooObject
      orderArray: [] // replace the order-array with new empty array.
      }))
    }
  }),