Add Seeds type for preparings seeds for a database

Sources/StructuredQueriesCore/Documentation.docc/Articles/InsertStatements.md

@@ -447,3 +447,7 @@ clause:
 ### Statement types
 
 - ``Insert``
+
+### Seeding a database
+
+- ``Seeds``

Sources/StructuredQueriesCore/SQLQueryExpression.swift

@@ -35,4 +35,11 @@ public struct SQLQueryExpression<QueryValue>: Statement {
   public init(_ expression: some QueryExpression<QueryValue>) {
     self.queryFragment = expression.queryFragment
   }
+
+  /// Creates a type erased query expression from a statement.
+  ///
+  /// - Parameter statement: A statement.
+  public init(_ statement: some Statement<QueryValue>) {
+    self.queryFragment = statement.query
+  }
 }

Sources/StructuredQueriesCore/Seeds.swift

@@ -0,0 +1,105 @@
+/// A type that can prepare statements to seed a database's initial state.
+public struct Seeds: Sequence {
+  let seeds: [any Table]
+
+  /// Prepares a number of batched insert statements to be executed.
+  ///
+  /// ```swift
+  /// Seeds {
+  ///   SyncUp(id: 1, seconds: 60, theme: .appOrange, title: "Design")
+  ///   SyncUp(id: 2, seconds: 60 * 10, theme: .periwinkle, title: "Engineering")
+  ///   SyncUp(id: 3, seconds: 60 * 30, theme: .poppy, title: "Product")
+  ///
+  ///   for name in ["Blob", "Blob Jr", "Blob Sr", "Blob Esq", "Blob III", "Blob I"] {
+  ///     Attendee.Draft(name: name, syncUpID: 1)
+  ///   }
+  ///   for name in ["Blob", "Blob Jr"] {
+  ///     Attendee.Draft(name: name, syncUpID: 2)
+  ///   }
+  ///   for name in ["Blob Sr", "Blob Jr"] {
+  ///     Attendee.Draft(name: name, syncUpID: 3)
+  ///   }
+  /// }
+  /// // INSERT INTO "syncUps"
+  /// //   ("id", "seconds", "theme", "title")
+  /// // VALUES
+  /// //   (1, 60, 'appOrange', 'Design'),
+  /// //   (2, 600, 'periwinkle', 'Engineering'),
+  /// //   (3, 1800, 'poppy', 'Product');
+  /// // INSERT INTO "attendees"
+  /// //   ("id", "name", "syncUpID")
+  /// // VALUES
+  /// //   (NULL, 'Blob', 1),
+  /// //   (NULL, 'Blob Jr', 1),
+  /// //   (NULL, 'Blob Sr', 1),
+  /// //   (NULL, 'Blob Esq', 1),
+  /// //   (NULL, 'Blob III', 1),
+  /// //   (NULL, 'Blob I', 1),
+  /// //   (NULL, 'Blob', 2),
+  /// //   (NULL, 'Blob Jr', 2),
+  /// //   (NULL, 'Blob Sr', 3),
+  /// //   (NULL, 'Blob Jr', 3);
+  /// ```
+  ///
+  /// And then you can iterate over each insert statement and execute it given a database
+  /// connection. For example, using the [SharingGRDB][] driver:
+  ///
+  /// ```swift
+  /// try database.write { db in
+  ///   let seeds = Seeds {
+  ///     // ...
+  ///   }
+  ///   for insert in seeds {
+  ///     try db.execute(insert)
+  ///   }
+  /// }
+  /// ```
+  ///
+  /// > Tip: [SharingGRDB][] extends GRDB's `Database` connection with a `seed` method that can
+  /// > build and insert records in a single step:
+  /// >
+  /// > ```swift
+  /// > try db.seed {
+  /// >   // ...
+  /// > }
+  /// > ```
+  ///
+  /// [SharingGRDB]: https://github.com/pointfreeco/sharing-grdb
+  ///
+  /// - Parameter build: A result builder closure that prepares statements to insert every built row.
+  public init(@InsertValuesBuilder<any Table> _ build: () -> [any Table]) {
+    self.seeds = build()
+  }
+
+  public func makeIterator() -> Iterator {
+    Iterator(seeds: seeds)
+  }
+
+  public struct Iterator: IteratorProtocol {
+    var seeds: [any Table]
+
+    public mutating func next() -> SQLQueryExpression<Void>? {
+      guard let first = seeds.first else { return nil }
+
+      let firstType = type(of: first)
+
+      if let firstType = firstType as? any TableDraft.Type {
+        func insertBatch<T: TableDraft>(_: T.Type) -> SQLQueryExpression<Void> {
+          let batch = Array(seeds.lazy.prefix { $0 is T }.compactMap { $0 as? T })
+          defer { seeds.removeFirst(batch.count) }
+          return SQLQueryExpression(T.PrimaryTable.insert(batch))
+        }
+
+        return insertBatch(firstType)
+      } else {
+        func insertBatch<T: StructuredQueriesCore.Table>(_: T.Type) -> SQLQueryExpression<Void> {
+          let batch = Array(seeds.lazy.prefix { $0 is T }.compactMap { $0 as? T })
+          defer { seeds.removeFirst(batch.count) }
+          return SQLQueryExpression(T.insert(batch))
+        }
+
+        return insertBatch(firstType)
+      }
+    }
+  }
+}

Tests/StructuredQueriesTests/Support/Schema.swift

@@ -70,7 +70,7 @@ extension Database {
   static func `default`() throws -> Database {
     let db = try Database()
     try db.migrate()
-    try db.createMockData()
+    try db.seedDatabase()
     return db
   }
 
@@ -145,136 +145,107 @@ extension Database {
     )
   }
 
-  func createMockData() throws {
-    try createDebugUsers()
-    try createDebugRemindersLists()
-    try createDebugReminders()
-    try createDebugTags()
-  }
-
-  func createDebugUsers() throws {
-    try execute(
-      User.insert {
-        $0.name
-      } values: {
-        "Blob"
-        "Blob Jr"
-        "Blob Sr"
-      }
-    )
-  }
-
-  func createDebugRemindersLists() throws {
-    try execute(
-      RemindersList.insert {
-        ($0.color, $0.title)
-      } values: {
-        (0x4a99ef, "Personal")
-        (0xed8935, "Family")
-        (0xb25dd3, "Business")
-      }
-    )
-  }
-
-  func createDebugReminders() throws {
-    let now = Date(timeIntervalSinceReferenceDate: 0)
-    try execute(
-      Reminder.insert([
-        Reminder.Draft(
-          assignedUserID: 1,
-          dueDate: now,
-          notes: """
-            Milk, Eggs, Apples
-            """,
-          remindersListID: 1,
-          title: "Groceries"
-        ),
-        Reminder.Draft(
-          dueDate: now.addingTimeInterval(-60 * 60 * 24 * 2),
-          isFlagged: true,
-          remindersListID: 1,
-          title: "Haircut"
-        ),
-        Reminder.Draft(
-          dueDate: now,
-          notes: "Ask about diet",
-          priority: .high,
-          remindersListID: 1,
-          title: "Doctor appointment"
-        ),
-        Reminder.Draft(
-          dueDate: now.addingTimeInterval(-60 * 60 * 24 * 190),
-          isCompleted: true,
-          remindersListID: 1,
-          title: "Take a walk"
-        ),
-        Reminder.Draft(
-          remindersListID: 1,
-          title: "Buy concert tickets"
-        ),
-        Reminder.Draft(
-          dueDate: now.addingTimeInterval(60 * 60 * 24 * 2),
-          isFlagged: true,
-          priority: .high,
-          remindersListID: 2,
-          title: "Pick up kids from school"
-        ),
-        Reminder.Draft(
-          dueDate: now.addingTimeInterval(-60 * 60 * 24 * 2),
-          isCompleted: true,
-          priority: .low,
-          remindersListID: 2,
-          title: "Get laundry"
-        ),
-        Reminder.Draft(
-          dueDate: now.addingTimeInterval(60 * 60 * 24 * 4),
-          isCompleted: false,
-          priority: .high,
-          remindersListID: 2,
-          title: "Take out trash"
-        ),
-        Reminder.Draft(
-          dueDate: now.addingTimeInterval(60 * 60 * 24 * 2),
-          notes: """
-            Status of tax return
-            Expenses for next year
-            Changing payroll company
-            """,
-          remindersListID: 3,
-          title: "Call accountant"
-        ),
-        Reminder.Draft(
-          dueDate: now.addingTimeInterval(-60 * 60 * 24 * 2),
-          isCompleted: true,
-          priority: .medium,
-          remindersListID: 3,
-          title: "Send weekly emails"
-        ),
-      ])
-    )
-  }
-
-  func createDebugTags() throws {
-    try execute(
-      Tag.insert(\.title) {
-        "car"
-        "kids"
-        "someday"
-        "optional"
-      }
-    )
-    try execute(
-      ReminderTag.insert {
-        ($0.reminderID, $0.tagID)
-      } values: {
-        (1, 3)
-        (1, 4)
-        (2, 3)
-        (2, 4)
-        (4, 1)
-        (4, 2)
-      }
-    )
+  func seedDatabase() throws {
+    try Seeds {
+      User(id: 1, name: "Blob")
+      User(id: 2, name: "Blob Jr")
+      User(id: 3, name: "Blob Sr")
+      RemindersList(id: 1, color: 0x4a99ef, title: "Personal")
+      RemindersList(id: 2, color: 0xed8935, title: "Family")
+      RemindersList(id: 3, color: 0xb25dd3, title: "Business")
+      let now = Date(timeIntervalSinceReferenceDate: 0)
+      Reminder(
+        id: 1,
+        assignedUserID: 1,
+        dueDate: now,
+        notes: """
+          Milk, Eggs, Apples
+          """,
+        remindersListID: 1,
+        title: "Groceries"
+      )
+      Reminder(
+        id: 2,
+        dueDate: now.addingTimeInterval(-60 * 60 * 24 * 2),
+        isFlagged: true,
+        remindersListID: 1,
+        title: "Haircut"
+      )
+      Reminder(
+        id: 3,
+        dueDate: now,
+        notes: "Ask about diet",
+        priority: .high,
+        remindersListID: 1,
+        title: "Doctor appointment"
+      )
+      Reminder(
+        id: 4,
+        dueDate: now.addingTimeInterval(-60 * 60 * 24 * 190),
+        isCompleted: true,
+        remindersListID: 1,
+        title: "Take a walk"
+      )
+      Reminder(
+        id: 5,
+        remindersListID: 1,
+        title: "Buy concert tickets"
+      )
+      Reminder(
+        id: 6,
+        dueDate: now.addingTimeInterval(60 * 60 * 24 * 2),
+        isFlagged: true,
+        priority: .high,
+        remindersListID: 2,
+        title: "Pick up kids from school"
+      )
+      Reminder(
+        id: 7,
+        dueDate: now.addingTimeInterval(-60 * 60 * 24 * 2),
+        isCompleted: true,
+        priority: .low,
+        remindersListID: 2,
+        title: "Get laundry"
+      )
+      Reminder(
+        id: 8,
+        dueDate: now.addingTimeInterval(60 * 60 * 24 * 4),
+        isCompleted: false,
+        priority: .high,
+        remindersListID: 2,
+        title: "Take out trash"
+      )
+      Reminder(
+        id: 9,
+        dueDate: now.addingTimeInterval(60 * 60 * 24 * 2),
+        notes: """
+          Status of tax return
+          Expenses for next year
+          Changing payroll company
+          """,
+        remindersListID: 3,
+        title: "Call accountant"
+      )
+      Reminder(
+        id: 10,
+        dueDate: now.addingTimeInterval(-60 * 60 * 24 * 2),
+        isCompleted: true,
+        priority: .medium,
+        remindersListID: 3,
+        title: "Send weekly emails"
+      )
+      Tag(id: 1, title: "car")
+      Tag(id: 2, title: "kids")
+      Tag(id: 3, title: "someday")
+      Tag(id: 4, title: "optional")
+      ReminderTag(reminderID: 1, tagID: 3)
+      ReminderTag(reminderID: 1, tagID: 4)
+      ReminderTag(reminderID: 2, tagID: 3)
+      ReminderTag(reminderID: 2, tagID: 4)
+      ReminderTag(reminderID: 4, tagID: 1)
+      ReminderTag(reminderID: 4, tagID: 2)
+    }
+    .forEach(execute)
   }
 }