黑鸟 (Blackbird)

import Blackbird

struct Post: BlackbirdModel {
    @BlackbirdColumn var id: Int
    @BlackbirdColumn var title: String
    @BlackbirdColumn var url: URL?
}

struct Post: BlackbirdModel {
    static var primaryKey: [BlackbirdColumnKeyPath] = [ \.$guid, \.$id ]

    static var indexes: [[BlackbirdColumnKeyPath]] = [
        [ \.$title ],
        [ \.$publishedDate, \.$format ],
    ]

    static var uniqueIndexes: [[BlackbirdColumnKeyPath]] = [
        [ \.$guid ],
    ]
    
    enum Format: Int, BlackbirdIntegerEnum {
        case markdown
        case html
    }
    
    @BlackbirdColumn var id: Int
    @BlackbirdColumn var guid: String
    @BlackbirdColumn var title: String
    @BlackbirdColumn var publishedDate: Date?
    @BlackbirdColumn var format: Format
    @BlackbirdColumn var url: URL?
    @BlackbirdColumn var image: Data?
}

let post = Post(id: 1, title: "What I had for breakfast")
try await post.write(to: db)

// Fetch by primary key
let post = try await Post.read(from: db, id: 2)

// Or with a WHERE condition, using compiler-checked key-paths:
let posts = try await Post.read(from: db, matching: \.$title == "Sports")

// Select custom columns, with row dictionaries typed by key-path:
for row in try await Post.query(in: db, columns: [\.$id, \.$image], matching: \.$url != nil) {
    let postID = row[\.$id]       // returns Int
    let imageData = row[\.$image] // returns Data?
}

try await Post.query(in: db, "UPDATE $T SET format = ? WHERE date < ?", .html, date)

let posts = try await Post.read(from: db, sqlWhere: "title LIKE ? ORDER BY RANDOM()", "Sports%")

for row in try await Post.query(in: db, "SELECT MAX(id) AS max FROM $T WHERE url = ?", url) {
    let maxID = row["max"]?.intValue
}

let listener = Post.changePublisher(in: db).sink { change in
    if change.hasPrimaryKeyChanged(7) {
        print("Post 7 has changed")
    }

    if change.hasColumnChanged(\.$title) {
        print("A title has changed")
    }
}

// Or monitor a single column by key-path:
let listener = Post.changePublisher(in: db, columns: [\.$title]).sink { _ in
    print("A post's title changed")
}

// Or listen for changes for a specific primary key:
let listener = Post.changePublisher(in: db, primaryKey: 3, columns: [\.$title]).sink { _ in
    print("Post 3's title changed")
}

struct RootView: View {
    // The database that all child views will automatically use
    @StateObject var database = try! Blackbird.Database.inMemoryDatabase()

    var body: some View {
        PostListView()
        .environment(\.blackbirdDatabase, database)
    }
}

struct PostListView: View {
    // Async-loading, auto-updating array of matching instances
    @BlackbirdLiveModels({ try await Post.read(from: $0, orderBy: .ascending(\.$id)) }) var posts
    
    // Async-loading, auto-updating rows from a custom query
    @BlackbirdLiveQuery(tableName: "Post", { try await $0.query("SELECT MAX(id) AS max FROM Post") }) var maxID

    var body: some View {
        VStack {
            if posts.didLoad {
                List {
                    ForEach(posts.results) { post in
                        NavigationLink(destination: PostView(post: post.liveModel)) {
                            Text(post.title)
                        }
                    }
                }
            } else {
                ProgressView()
            }
        }
        .navigationTitle(maxID.didLoad ? "\(maxID.results.first?["max"]?.intValue ?? 0) posts" : "Loading…")
    }
}

struct PostView: View {
    // Auto-updating instance
    @BlackbirdLiveModel var post: Post?

    var body: some View {
        VStack {
            if let post {
                Text(post.title)
            }
        }
    }
}

let db = try Blackbird.Database(path: "/tmp/db.sqlite")

// SELECT with parameterized queries
for row in try await db.query("SELECT id FROM posts WHERE state = ?", 1) {
    let id = row["id"]?.intValue
    // ...
}

// Run direct queries
try await db.execute("UPDATE posts SET comments = NULL")

// Transactions with synchronous queries
try await db.transaction { core in
    try core.query("INSERT INTO posts VALUES (?, ?)", 16, "Sports!")
    try core.query("INSERT INTO posts VALUES (?, ?)", 17, "Dewey Defeats Truman")
}