`.replaceCollection()`

Replace all members of the specified collection (e.g. the comments of BlogPost #4).

usage

await Something.replaceCollection(parentId, association)
.members(childIds);

Usage

	Argument	Type	Details
1	parentId	((number)) or ((string))	The primary key value(s) (i.e. ids) for the parent record(s).
Must be a number or string (e.g. `'507f191e810c19729de860ea'` or `49`).
Alternatively, an array of numbers or strings may be specified (e.g. `['507f191e810c19729de860ea', '14832ace0c179de897']` or `[49, 32, 37]`). In this case, the child records will be replaced in each parent record.
2	association	((string))	The name of the plural ("collection") association (e.g. "pets")
3	childIds	((array))	The primary key values (i.e. ids) for the child records that will be the new members of the association. Note that this does not create these records or destroy the old ones, it just attaches/detaches records to/from the specified parent(s).

Errors

Name	Type	When?
UsageError	((Error))	Thrown if something invalid was passed in.
AdapterError	((Error))	Thrown if something went wrong in the database adapter.
Error	((Error))	Thrown if anything else unexpected happens.

See Concepts > Models and ORM > Errors for examples of negotiating errors in Sails and Waterline.

Example

For user 3, replace all pets in the "pets" collection with pets 99 and 98:

javascript

await User.replaceCollection(3, 'pets')
.members([99,98]);

Edge cases

If the parent id does not actually correspond with an existing, persisted record, then this will do nothing.
If one of the child ids does not actually correspond with an existing, persisted record, then that child id will be ignored, and only those members that correspond with the other provided child ids will be included in the replacement collection.
If an empty array of child ids is provided, or if none of the provided child ids correspond to existing records, then this will detach all child records from the parent.

Notes

This method can be used with await, promise chaining, or traditional Node callbacks.

If the association is "2-way" (meaning it has via) then the child records will be modified accordingly. If the attribute on the other side is singular, the each newly-linked-or-unlinked child record's foreign key will be changed. If it's plural, then each child record's collection will be modified accordingly.

In addition, if the via points at a singular ("model") attribute on the other side, then .addToCollection() will "steal" these child records if necessary. For example, imagine you have an Employee model with this plural ("collection") attribute: involvedInPurchases: { collection: 'Purchase', via: 'cashier' }. If you executed Employee.addToCollection(7, 'involvedInPurchases', [47]) to assign this purchase to employee #7 (Dolly), but purchase #47 was already associated with a different employee (e.g. #12, Motoki), then this would "steal" the purchase from Motoki and give it to Dolly. In other words, if you executed Employee.find([7, 12]).populate('involvedInPurchases'), Dolly's involvedInPurchases array would contain purchase #47 and Motoki's would not.