Public Database.schemaSource and withSchemaSource(_:execute:)

Author: groue

GRDB/Core/Configuration.swift

@@ -430,9 +430,11 @@ public struct Configuration: Sendable {
     /// by SQLite. For example, a custom schema source can help record types
     /// that read or write in a database view.
     ///
-    /// The schema source has not effect during database migrations
-    /// performed by ``DatabaseMigrator``. Those access the raw SQLite
-    /// schema, unaltered.
+    /// The schema source is automatically disabled during database
+    /// migrations performed by ``DatabaseMigrator``: those access the raw
+    /// SQLite schema, unaltered. If a migration needs a schema source,
+    /// you may call ``Database/withSchemaSource(_:execute:)`` from within
+    /// the body of a migration.
     public var schemaSource: (any DatabaseSchemaSource)?
 
     // MARK: - Factory Configuration

GRDB/Core/Database+Schema.swift

@@ -35,8 +35,8 @@ extension Database {
 
     // MARK: - Database Schema
 
-    /// Runs the provided closure with the provided schema source.
-    func withSchemaSource<T>(
+    /// Executes the wrapped statements with the provided schema source.
+    public func withSchemaSource<T>(
         _ schemaSource: (any DatabaseSchemaSource)?,
         execute block: () throws -> T
     ) rethrows -> T {

GRDB/Core/Database.swift

@@ -113,6 +113,11 @@ let SQLITE_TRANSIENT = unsafeBitCast(OpaquePointer(bitPattern: -1), to: sqlite3_
 /// - ``resumeNotification``
 /// - ``suspendNotification``
 ///
+/// ### The Schema Source
+///
+/// - ``schemaSource``
+/// - ``withSchemaSource(_:execute:)``
+///
 /// ### Other Database Operations
 ///
 /// - ``add(tokenizer:)``
@@ -187,6 +192,19 @@ public final class Database: CustomStringConvertible, CustomDebugStringConvertib
     /// The database configuration.
     public let configuration: Configuration
 
+    /// The current schema source.
+    ///
+    /// By default, it is the ``Configuration/schemaSource``
+    /// of ``configuration``. To modify the schema source,
+    /// use ``withSchemaSource(_:execute:)``.
+    ///
+    /// The schema source is automatically disabled (nil) during database
+    /// migrations performed by ``DatabaseMigrator``: those access the raw
+    /// SQLite schema, unaltered. If a migration needs a schema source,
+    /// you may call ``Database/withSchemaSource(_:execute:)`` from within
+    /// the body of a migration.
+    public internal(set) var schemaSource: (any DatabaseSchemaSource)?
+    
     /// A description of this database connection.
     ///
     /// The returned string is based on the ``Configuration/label``
@@ -276,9 +294,6 @@ public final class Database: CustomStringConvertible, CustomDebugStringConvertib
     /// The cache for the available database schemas (main, temp, attached databases).
     var schemaCache = SchemaCache()
 
-    /// To modify the schemaSource, use `withSchemaSource`.
-    var schemaSource: (any DatabaseSchemaSource)?
-    
     /// The cache for statements managed by GRDB. It is distinct from
     /// `publicStatementCache` so that we do not mess with statement arguments
     /// set by the user.

Tests/GRDBTests/DatabaseMigratorTests.swift

@@ -1125,22 +1125,45 @@ class DatabaseMigratorTests : GRDBTestCase {
             migrator.registerMigration("A") { db in
                 try db.execute(sql: "CREATE VIEW myView as SELECT 1 AS id")
                 // Cache is empty, and schemaSource is disabled.
+                XCTAssertNil(db.schemaSource)
                 XCTAssertThrowsError(try db.primaryKey("myView"))
             }
             try migrator.migrate(dbQueue)
         }
 
         try dbQueue.inDatabase { db in
             // Cache was cleared, and schemaSource is active.
+            XCTAssertNotNil(db.schemaSource)
             XCTAssertNoThrow(try db.primaryKey("myView"))
         }
 
         do {
             migrator.registerMigration("B") { db in
                 // Cache was cleared again, and schemaSource is disabled.
+                XCTAssertNil(db.schemaSource)
                 XCTAssertThrowsError(try db.primaryKey("myView"))
             }
             try migrator.migrate(dbQueue)
         }
     }
+    
+    func test_schemaSource_can_be_restored_during_migrations() throws {
+        struct SchemaSource: DatabaseSchemaSource {
+            func columnsForPrimaryKey(_ db: Database, inView view: DatabaseObjectID) throws -> [String]? {
+                ["id"]
+            }
+        }
+        
+        dbConfiguration.schemaSource = SchemaSource()
+        let dbQueue = try makeDatabaseQueue()
+        var migrator = DatabaseMigrator()
+        
+        migrator.registerMigration("A") { db in
+            try db.execute(sql: "CREATE VIEW myView as SELECT 1 AS id")
+            try db.withSchemaSource(SchemaSource()) {
+                XCTAssertNoThrow(try db.primaryKey("myView"))
+            }
+        }
+        try migrator.migrate(dbQueue)
+    }
 }