Array

extension Array where Element: Model

Available where Element: Model

  • Returns a Dictionary mapping IDs of the array elements to counts of how many associated Children each element has in the database.

    Result is a Dictionary instead of an array because (I think?) SQL may coalesce array values with the same ID, resulting in a output array smaller than the input. Also, SQL won’t return rows for UUIDS that aren’t in the table.

    If the database is SQL-backed, this method uses SQLKit to get counts for the # of related rows of each array element all with one call. This is considerably faster than the Fluent-only path, saving ~1.2ms per array element. For a 50 element array, the SQLKit path will take ~2ms, and the Fluent path will take ~75ms.

    The filter callbacks are used to modify the Fluent or SQLKit query before it runs. They are given the appropriate type of partially-built query builder. The intent is that the filters express the same operation (only one will be used for any connected database).

    Declaration

    Swift

    public func childCountsPerModel<ChildModel: Model>(
	atPath: KeyPath<Element, ChildrenProperty<Element, ChildModel>>,
	on db: Database,
	fluentFilter: @escaping (QueryBuilder<ChildModel>) -> Void = { _ in },
	sqlFilter: ((SQLSelectBuilder) -> Void)? = nil
)
	async throws -> [Element.IDValue: Int]
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