MutableRelation Protocol Reference


                    
                    
                    add(_:)

Undocumented

Declaration

Swift

func add(_ row: Row) -> Result<Int64, RelationError>


                    
                    
                    delete(_:)

Undocumented

Declaration

Swift

func delete(_ query: SelectExpression) -> Result<Void, RelationError>

asyncAdd(_:) Extension method
Undocumented
Declaration
Swift

func asyncAdd(_ row: Row)
asyncDelete(_:) Extension method
Undocumented
Declaration
Swift

func asyncDelete(_ query: SelectExpression)


                    
                    
                    cascadingDelete(_:affectedRelations:cascade:update:completionCallback:)

Extension method

Perform a cascading delete on the relation. The query is used for the initial deletion run. For every deleted row, cascade is called to get further deletions to perform. When nothing remains to be deleted, completionCallback is called.

Declaration

Swift

public func cascadingDelete(
    _ query: SelectExpression,
    affectedRelations: [MutableRelation],
    cascade: @escaping (MutableRelation, Row) -> [(MutableRelation, SelectExpression)],
    update: @escaping (MutableRelation, Row) -> [CascadingUpdate] = { _, _ in [] },
    completionCallback: @escaping (Result<Void, RelationError>) -> Void = { _ in })

Parameters

`query`	The initial query for rows to delete on this relation.
`affectedRelations`	An array of all relations that this operation will affect. This array must include all relations that will be updated or deleted, otherwise notifications won’t work right. It is acceptable to pass in more than will actually be changed. This will generate spurious but harmless change notifications.
`cascade`	Called for each deleted row to get cascades. Must return an array of `(MutableRelation, SelectExpression)` pairs indicating what to delete next. The same relation can be specified to perform a cascading delete within the relation, or a different one can be specified to do cross-relation cascades.
`update`	Called for each deleted row to get updates. Must return an array of CascadingUpdate instances indicating what updates to apply on the basis of the deleted row.
`completionCallback`	Called when the cascading delete completes.

treeDelete(_:parentAttribute:childAttribute:update:completionCallback:) Extension method
Do a tree deletion in the relation. This will delete all rows matching the query, as well as all rows whose childAttribute matches the value in the parentAttribute of a deleted row. This proceeds recursively until the whole tree is deleted, or an error occurs.
Declaration
Swift

public func treeDelete( _ query: SelectExpression, parentAttribute: Attribute, childAttribute: Attribute, update: @escaping (MutableRelation, Row) -> [CascadingUpdate] = { _, _ in [] }, completionCallback: @escaping (Result<Void, RelationError>) -> Void = { _ in })