SwiftUIDemo.swift

import SharingGRDB
import SwiftUI

struct SwiftUIDemo: SwiftUICaseStudy {
  let readMe = """
    This demonstrates how to use the `fetchAll` and `fetchOne` queries directly in a SwiftUI view. \
    The tools listen for changes in the database so that when the table changes it automatically \
    updates state and re-renders the view.

    You can also delete rows by swiping on a row and tapping the "Delete" button.
    """
  let caseStudyTitle = "SwiftUI Views"

  @FetchAll(Fact.order { $0.id.desc() }, animation: .default)
  private var facts
  @FetchOne(Fact.count(), animation: .default)
  var factsCount = 0

  @Dependency(\.defaultDatabase) var database

  var body: some View {
    List {
      Section {
        Text("Facts: \(factsCount)")
          .font(.largeTitle)
          .bold()
          .contentTransition(.numericText(value: Double(factsCount)))
      }
      Section {
        ForEach(facts) { fact in
          Text(fact.body)
        }
      }
    }
    .task {
      do {
        var number = 0
        while true {
          try await Task.sleep(for: .seconds(1))
          number += 1
          let fact = try await String(
            decoding: URLSession.shared
              .data(from: URL(string: "http://numberapi.com/\(number)")!).0,
            as: UTF8.self
          )
          try await database.write { db in
            try Fact.insert(Fact.Draft(body: fact))
              .execute(db)
          }
        }
      } catch {}
    }
  }
}

@Table
private struct Fact: Identifiable {
  let id: Int
  var body: String
}

extension DatabaseWriter where Self == DatabaseQueue {
  static var swiftUIDatabase: Self {
    let databaseQueue = try! DatabaseQueue()
    var migrator = DatabaseMigrator()
    migrator.registerMigration("Create 'facts' table") { db in
      try #sql(
        """
        CREATE TABLE "facts" (
          "id" INTEGER PRIMARY KEY AUTOINCREMENT,
          "body" TEXT NOT NULL
        )
        """
      )
      .execute(db)
    }
    try! migrator.migrate(databaseQueue)
    return databaseQueue
  }
}

#Preview {
  let _ = prepareDependencies {
    $0.defaultDatabase = .swiftUIDatabase
  }
  NavigationStack {
    CaseStudyView {
      SwiftUIDemo()
    }
  }
}