improve model helpers?

Author: tanner0101

Sources/FluentPostgreSQL/PostgreSQLModel.swift

@@ -1,6 +1,17 @@
-public protocol PostgreSQLModel: Model where Self.Database == PostgreSQLDatabase { }
+public protocol PostgreSQLModel: Model where Self.Database == PostgreSQLDatabase, Self.ID == Int {
+    /// This model's unique identifier.
+    var id: Int? { get set }
+}
 
 extension PostgreSQLModel {
     /// See `Model.Database`
     public typealias Database = PostgreSQLDatabase
+
+    /// See `Model.ID`
+    public typealias ID = Int
+
+    /// See `Model.idKey`
+    public static var idKey: IDKey { return \.id }
 }
+
+public protocol PostgreSQLPivot: Pivot, PostgreSQLModel { }

Sources/FluentPostgreSQL/PostgreSQLPivot.swift

@@ -0,0 +1,19 @@
+import Foundation
+
+public protocol PostgreSQLUUIDModel: Model where Self.Database == PostgreSQLDatabase, Self.ID == UUID {
+    /// This model's unique identifier.
+    var id: UUID? { get set }
+}
+
+extension PostgreSQLUUIDModel {
+    /// See `Model.Database`
+    public typealias Database = PostgreSQLDatabase
+
+    /// See `Model.ID`
+    public typealias ID = UUID
+
+    /// See `Model.idKey`
+    public static var idKey: IDKey { return \.id }
+}
+
+public protocol PostgreSQLUUIDPivot: Pivot, PostgreSQLUUIDModel { }

Sources/FluentPostgreSQL/PostgreSQLUUIDModel.swift

@@ -84,6 +84,26 @@ class FluentPostgreSQLTests: XCTestCase {
         try benchmarker.benchmarkIndexSupporting_withSchema()
     }
 
+    func testMinimumViableModelDeclaration() throws {
+        /// NOTE: these must never fail to build
+        struct Foo: PostgreSQLModel {
+            var id: Int?
+            var name: String
+        }
+        final class Bar: PostgreSQLModel {
+            var id: Int?
+            var name: String
+        }
+        struct Baz: PostgreSQLUUIDModel {
+            var id: UUID?
+            var name: String
+        }
+        final class Qux: PostgreSQLUUIDModel {
+            var id: UUID?
+            var name: String
+        }
+    }
+
     static let allTests = [
         ("testSchema", testSchema),
         ("testModels", testModels),
@@ -97,6 +117,7 @@ class FluentPostgreSQLTests: XCTestCase {
         ("testSoftDeletable", testSoftDeletable),
         ("testReferentialActions", testReferentialActions),
         ("testIndexSupporting", testIndexSupporting),
+        ("testMinimumViableModelDeclaration", testMinimumViableModelDeclaration),
     ]
 }