hasMany(_:key:using:)

Creates a HasManyAssociation between Self and the destination TableRecord type.

static func hasMany<Destination>(_ destination: Destination.Type, key: String? = nil, using foreignKey: ForeignKey? = nil) -> HasManyAssociation<Self, Destination> where Destination : TableRecord

Mangled symbol

s4GRDB11TableRecordPAAE7hasMany_3key5usingAA03HasE11AssociationVyxqd__Gqd__m_SSSgAA10ForeignKeyVSgtAaBRd__lFZ What are these?

FNV24 hash: 45AXO

Parameters

destination: The record type at the other side of the association.
key: The association key. By default, it is Destination.databaseTableName.
foreignKey: An eventual foreign key. You need to provide one when no foreign key exists to the destination table, or several foreign keys exist.

For example:

struct Book: TableRecord { }
struct Author: TableRecord {
    static let books = hasMany(Book.self)
}

The association lets you define requests that involve both the source and the destination type.

For example, we can fetch all authors with all their books:

struct AuthorInfo: FetchableRecord, Decodable {
    var author: Author
    var books: [Book]
}

try dbQueue.read { db in
    let request = Author
        .including(all: Author.books)
        .asRequest(of: AuthorInfo.self)
    let authorInfos = try request.fetchAll(db)
    for authorInfo in authorInfos {
        print("\(authorInfo.author.name) wrote \(authorInfo.books.count) books")
    }
}

The association can also help fetching associated records:

try dbQueue.read { db in
    let author: Author = ...
    let books: [Book] = author
        .request(for: Author.books)
        .fetchAll(db)
}

For more information about this association, see HasManyAssociation.

Methods that build requests involving associations are defined in the JoinableRequest protocol.