add iOS

iOS-SwiftUI-Code/GRDB.swift-6.29.3/Documentation/Playgrounds/Associations.playground/Contents.swift

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+//: To run this playground:
+//:
+//: - Open GRDB.xcworkspace
+//: - Select the GRDB scheme: menu Product > Scheme > GRDB
+//: - Build: menu Product > Build
+//: - Select the playground in the Playgrounds Group
+//: - Run the playground
+
+import GRDB
+
+//: Open a database connection
+
+var configuration = Configuration()
+configuration.prepareDatabase { db in
+    db.trace { print("SQL> \($0)") }
+}
+let dbQueue = try DatabaseQueue(configuration: configuration)
+
+//: Use a migrator to define the database schema
+
+var migrator = DatabaseMigrator()
+
+migrator.registerMigration("createLibrary") { db in
+    try db.create(table: "author") { t in
+        t.autoIncrementedPrimaryKey("id")
+        t.column("name", .text).notNull()
+    }
+    
+    try db.create(table: "book") { t in
+        t.autoIncrementedPrimaryKey("id")
+        t.column("title", .text).notNull()
+        t.belongsTo("author", onDelete: .cascade).notNull()
+    }
+}
+
+try migrator.migrate(dbQueue)
+
+//: Define Record types
+
+struct Author: Codable, FetchableRecord, MutablePersistableRecord {
+    var id: Int64?
+    var name: String
+    
+    mutating func didInsert(_ inserted: InsertionSuccess) {
+        id = inserted.rowID
+    }
+}
+
+struct Book: Codable, FetchableRecord, MutablePersistableRecord {
+    var id: Int64?
+    var authorId: Int64
+    var title: String
+    
+    mutating func didInsert(_ inserted: InsertionSuccess) {
+        id = inserted.rowID
+    }
+}
+
+//: Define Associations
+
+extension Author {
+    static let books = hasMany(Book.self)
+    var books: QueryInterfaceRequest<Book> { request(for: Author.books) }
+}
+
+extension Book {
+    static let author = belongsTo(Author.self)
+    var author: QueryInterfaceRequest<Author> { request(for: Book.author) }
+}
+
+//: Populate the database
+
+print("----------")
+print("Populate the database")
+try dbQueue.write { db in
+    var melville = Author(id: nil, name: "Hermann Melville")
+    try melville.insert(db)
+    var mobyDick = Book(id: nil, authorId: melville.id!, title: "Moby-Dick")
+    try mobyDick.insert(db)
+
+    var genet = Author(id: nil, name: "Jean Genet")
+    try genet.insert(db)
+    var querelle = Book(id: nil, authorId: genet.id!, title: "Querelle de Brest")
+    try querelle.insert(db)
+    var lesBonnes = Book(id: nil, authorId: genet.id!, title: "Les Bonnes")
+    try lesBonnes.insert(db)
+}
+
+//: Fetch author information
+
+print("----------")
+print("Fetch author information")
+struct AuthorInfo {
+    var author: Author
+    var books: [Book]
+}
+let authorId = 2
+let authorInfo: AuthorInfo? = try dbQueue.read { db in
+    guard let author = try Author.fetchOne(db, key: authorId) else { return nil }
+    let books = try author.books.fetchAll(db)
+    return AuthorInfo(author: author, books: books)
+}
+if let authorInfo {
+    print("\(authorInfo.author.name) has written:")
+    for book in authorInfo.books {
+        print("- \(book.title)")
+    }
+}
+
+
+//: Fetch book information
+
+print("----------")
+print("Fetch book information")
+struct BookInfo: FetchableRecord, Codable {
+    var book: Book
+    var author: Author
+}
+let bookId = 1
+let bookInfo: BookInfo? = try dbQueue.read { db in
+    let request = Book
+        .filter(key: bookId)
+        .including(required: Book.author)
+    return try BookInfo.fetchOne(db, request)
+}
+if let bookInfo {
+    print("\(bookInfo.book.title) was written by \(bookInfo.author.name)")
+}
+
+//: Fetch all authorships
+
+print("----------")
+print("Fetch all authorships")
+struct Authorship: Decodable, FetchableRecord {
+    var book: Book
+    var author: Author
+}
+let authorships: [Authorship] = try dbQueue.read { db in
+    let request = Book.including(required: Book.author)
+    return try Authorship.fetchAll(db, request)
+}
+for authorship in authorships {
+    print("\(authorship.book.title) was written by \(authorship.author.name)")
+}

iOS-SwiftUI-Code/GRDB.swift-6.29.3/Documentation/Playgrounds/Associations.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' buildActiveScheme='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>