title: Redux nested state design
body: <p>Currently having a state which is getting more complicated an I'm wondering if i'm doing it wrong, see below for an example of a reducer i'm using. </p>
  
  <pre><code>case RECEIVE_DEPARTMENT_DAYDATA: 
      return {
          ...state,
          departments: {
              ...state.departments,
              [action.payload.targetDepartment]: {
                  ...state.departments[action.payload.targetDepartment],
                  dayData: {
                      ...state.departments[action.payload.targetDepartment].dayData,
                      [action.payload.day]: {
                          ...state.departments[action.payload.targetDepartment].dayData[action.payload.day],
                          [action.payload.targetField]: {
                              ...action.payload.data,
                              isFetching: false,
                              receivedAt: new Date(),
                              didInvaldiate: false,
                              didCall: true
                          }
                      }
                  }
              }
          }
      };
  </code></pre>
  
  <p>Is it better to move dayData to it's own reducer or does it make no difference?</p>