onDelete

onDelete - Effect

This effect allow us to delete items from arrays without mutations involved.
These deletions are managed via action.payload by default.

Example:

We have this state:

const initialState = {
  objectList: [{ id: 1 }, { id: 2 }, { id: 3 }]
};

And we want to delete objects by id. Then, we'd like to write:

dispatch({ type: actions.DELETE_ITEM, payload: 2 });

if we would like to delete the item with { id: 2 }, leading to:

objectList: [{ id: 1 }, { id: 3 }]

To achieve that, we write this as a reducer:

const reducerDescription = {
  [actions.DELETE_ITEM]: onDelete()
};

export default createReducer(initialState, reducerDescription);

Custom selectors

onDelete effect actually takes three parameters that are optional:

• leftSelector: How we are going to read the action for deletions; the identifier that we want to delete.
  (action, item) => any
  By default is
  action => action.payload
• rightSelector: How we are going to read each one of the list items.
  (item, action) => any
  By default is
  item => item.id
• filter: Actually, it is a comparison between the results of leftSelector and rightSelector calls. (item, action) => bool
  By default is:
  (item, action) => action.payload !== item.id