Allow using DatabaseSchema.deleteField(_:)` with SQLite (#92)

* Remove the artificial restriction on using ALTER TABLE DROP COLUMN (DatabaseSchema.deleteField(_:)) with SQLite; it has been supported since SQLite 3.35.0. Fixes #91.

* Can't link to stuff that's not in the same module. Fixes a DocC warning.

* Update SQLiteKit and FluentKit dependency requirements

Author: gwynne

Package.swift

@@ -13,8 +13,8 @@ let package = Package(
         .library(name: "FluentSQLiteDriver", targets: ["FluentSQLiteDriver"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/vapor/fluent-kit.git", from: "1.48.3"),
-        .package(url: "https://github.com/vapor/sqlite-kit.git", from: "4.5.0"),
+        .package(url: "https://github.com/vapor/fluent-kit.git", from: "1.48.4"),
+        .package(url: "https://github.com/vapor/sqlite-kit.git", from: "4.5.1"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.5.4"),
     ],
     targets: [

Package@swift-5.9.swift

@@ -13,8 +13,8 @@ let package = Package(
         .library(name: "FluentSQLiteDriver", targets: ["FluentSQLiteDriver"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/vapor/fluent-kit.git", from: "1.48.3"),
-        .package(url: "https://github.com/vapor/sqlite-kit.git", from: "4.5.0"),
+        .package(url: "https://github.com/vapor/fluent-kit.git", from: "1.48.4"),
+        .package(url: "https://github.com/vapor/sqlite-kit.git", from: "4.5.1"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.5.4"),
     ],
     targets: [

Sources/FluentSQLiteDriver/FluentSQLiteConfiguration.swift

@@ -59,8 +59,8 @@ extension DatabaseConfigurationFactory {
     /// - Parameters:
     ///   - configuration: The underlying `SQLiteConfiguration`.
     ///   - maxConnnectionsPerEventLoop: Ignored. The value is always treated as 1.
-    ///   - dataEncoder: An ``SQLiteDataEncoder`` used to translate bound query parameters into `SQLiteData` values.
-    ///   - dataDecoder: An ``SQLiteDataDecoder`` used to translate `SQLiteData` values into output values.
+    ///   - dataEncoder: An `SQLiteDataEncoder` used to translate bound query parameters into `SQLiteData` values.
+    ///   - dataDecoder: An `SQLiteDataDecoder` used to translate `SQLiteData` values into output values.
     ///   - queryLogLevel: The level at which SQL queries issued through the Fluent or SQLKit interfaces will be logged.
     /// - Returns: A configuration factory,
     public static func sqlite(

Sources/FluentSQLiteDriver/FluentSQLiteDatabase.swift

@@ -48,12 +48,10 @@ struct FluentSQLiteDatabase: Database, SQLDatabase, SQLiteDatabase {
                 case .dataType(_, .enum(_)): return false
                 default: return true
             } }
-            guard schema.createConstraints.isEmpty, schema.updateFields.isEmpty,
-                  schema.deleteFields.isEmpty, schema.deleteConstraints.isEmpty
-            else {
+            guard schema.createConstraints.isEmpty, schema.updateFields.isEmpty, schema.deleteConstraints.isEmpty else {
                 return self.eventLoop.makeFailedFuture(FluentSQLiteUnsupportedAlter())
             }
-            if schema.createFields.isEmpty { // If there were only enum updates, bail out.
+            if schema.createFields.isEmpty, schema.deleteFields.isEmpty { // If there were only enum updates, bail out.
                 return self.eventLoop.makeSucceededFuture(())
             }
         }

Tests/FluentSQLiteDriverTests/FluentSQLiteDriverTests.swift

@@ -114,7 +114,7 @@ final class FluentSQLiteDriverTests: XCTestCase {
 
             func revert(on database: any Database) async throws {
                 try await database.schema("users")
-                    .deleteField("apple_id")
+                    .deleteUnique(on: "apple_id")
                     .update()
             }
         }
@@ -128,6 +128,31 @@ final class FluentSQLiteDriverTests: XCTestCase {
         }
         await XCTAssertNoThrowAsync(try await UserMigration_v1_0_0().revert(on: self.database))
     }
+    
+    // https://github.com/vapor/fluent-sqlite-driver/issues/91
+    func testDeleteFieldMigration() async throws {
+        struct UserMigration_v1_0_0: AsyncMigration {
+            func prepare(on database: any Database) async throws {
+                try await database.schema("users").id().field("email", .string, .required).field("password", .string, .required).create()
+            }
+            func revert(on database: any Database) async throws {
+                try await database.schema("users").delete()
+            }
+        }
+        struct UserMigration_v1_1_0: AsyncMigration {
+            func prepare(on database: any Database) async throws {
+                try await database.schema("users").deleteField("password").update()
+            }
+            func revert(on database: any Database) async throws {
+                try await database.schema("users").field("password", .string, .required).update()
+            }
+        }
+        
+        await XCTAssertNoThrowAsync(try await UserMigration_v1_0_0().prepare(on: self.database))
+        await XCTAssertNoThrowAsync(try await UserMigration_v1_1_0().prepare(on: self.database))
+        await XCTAssertNoThrowAsync(try await UserMigration_v1_1_0().revert(on: self.database))
+        await XCTAssertNoThrowAsync(try await UserMigration_v1_0_0().revert(on: self.database))
+    }
 
     func testCustomJSON() async throws {
         struct Metadata: Codable { let createdAt: Date }