Smart Selector

And now, we can use the ChildDefinition interface to create a selector that will retrieve the child entity from the parent entity. We can use this selector in our components to retrieve the child entity from the store.

Note that the createSmartSelector function takes an array of ChildDefinition objects. This allows us to create a selector that will retrieve multiple child entities from the parent entity. That is, one row may point to multiple children. By passing the array you can account for each of them with one call.

In the case where your User row might have some child field named, roles your createSmartSelector call might look like this:

export const selectUserChildren = createSmartSelector(selectUser, [
  {
    childFeature: 'shared',
    childEntity: 'roles',
    parentField: 'roles',
    parentFeature: 'shared',
    parentEntity: 'users',
    childSelector: selectRoles,
  },
]);

The first parameter to createSmartSelector expects a selector that returns the parent entity. If you want to use some other selector, you'll need to convert it to a selector that returns an Entity first. See Using With Existing Selectors for more information.