From bb789e3deece914f5538b59374ec8b2fe03f1951 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gwendal=20Roue=CC=81?= <gr@pierlis.com>
Date: Wed, 5 Jun 2024 18:40:42 +0200
Subject: [PATCH] QueryInterfaceRequest.deleteAndFetchIds

---
 CHANGELOG.md                                  |  4 ++
 .../Request/QueryInterfaceRequest.swift       | 71 +++++++++++++++++++
 Tests/GRDBTests/TableRecordDeleteTests.swift  | 24 +++++++
 3 files changed, 99 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c11a065357..4b24b020ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -125,6 +125,10 @@ GRDB adheres to [Semantic Versioning](https://semver.org/), with one exception:
 
 ---
 
+## Next Release
+
+- **New**: Added `QueryInterfaceRequest.deleteAndFetchIds(_:)` which returns the set of deleted ids.
+
 ## 6.27.0
 
 Released April 21, 2024
diff --git a/GRDB/QueryInterface/Request/QueryInterfaceRequest.swift b/GRDB/QueryInterface/Request/QueryInterfaceRequest.swift
index 2371ae81d7..1d0d7cdadd 100644
--- a/GRDB/QueryInterface/Request/QueryInterfaceRequest.swift
+++ b/GRDB/QueryInterface/Request/QueryInterfaceRequest.swift
@@ -61,6 +61,7 @@
 /// ### Batch Delete
 ///
 /// - ``deleteAll(_:)``
+/// - ``deleteAndFetchIds(_:)``
 /// - ``deleteAndFetchCursor(_:)``
 /// - ``deleteAndFetchAll(_:)``
 /// - ``deleteAndFetchSet(_:)``
@@ -625,6 +626,41 @@ extension QueryInterfaceRequest {
     {
         try Set(deleteAndFetchCursor(db))
     }
+
+    /// Executes a `DELETE RETURNING` statement and returns the set of
+    /// deleted ids.
+    ///
+    /// For example:
+    ///
+    /// ```swift
+    /// // Fetch the ids of deleted players
+    /// // DELETE FROM player RETURNING id
+    /// let request = Player.all()
+    /// let deletedPlayerIds = try request.deleteAndFetchIds(db)
+    /// ```
+    ///
+    /// - important: Make sure you check the documentation of the `RETURNING`
+    ///   clause, which describes important limitations and caveats:
+    ///   <https://www.sqlite.org/lang_returning.html#limitations_and_caveats>.
+    ///
+    /// - parameter db: A database connection.
+    /// - returns: A set of deleted ids.
+    /// - throws: A ``DatabaseError`` whenever an SQLite error occurs.
+    @available(iOS 13, macOS 10.15, tvOS 13, watchOS 6, *) // Identifiable
+    public func deleteAndFetchIds(_ db: Database)
+    throws -> Set<RowDecoder.ID>
+    where RowDecoder: TableRecord & Identifiable,
+    RowDecoder.ID: Hashable & DatabaseValueConvertible & StatementColumnConvertible
+    {
+        let primaryKey = try db.primaryKey(RowDecoder.databaseTableName)
+        GRDBPrecondition(
+            primaryKey.columns.count == 1,
+            "Fetching id requires a single-column primary key in the table \(databaseTableName)")
+        
+        let statement = try deleteAndFetchStatement(db, selection: [Column(primaryKey.columns[0])])
+        
+        return try RowDecoder.ID.fetchSet(statement)
+    }
 #else
     /// Returns a `DELETE RETURNING` prepared statement.
     ///
@@ -741,6 +777,41 @@ extension QueryInterfaceRequest {
     {
         try Set(deleteAndFetchCursor(db))
     }
+
+    /// Executes a `DELETE RETURNING` statement and returns the set of
+    /// deleted ids.
+    ///
+    /// For example:
+    ///
+    /// ```swift
+    /// // Fetch the ids of deleted players
+    /// // DELETE FROM player RETURNING id
+    /// let request = Player.all()
+    /// let deletedPlayerIds = try request.deleteAndFetchIds(db)
+    /// ```
+    ///
+    /// - important: Make sure you check the documentation of the `RETURNING`
+    ///   clause, which describes important limitations and caveats:
+    ///   <https://www.sqlite.org/lang_returning.html#limitations_and_caveats>.
+    ///
+    /// - parameter db: A database connection.
+    /// - returns: A set of deleted ids.
+    /// - throws: A ``DatabaseError`` whenever an SQLite error occurs.
+    @available(iOS 15, macOS 12, tvOS 15, watchOS 8, *) // SQLite 3.35.0+
+    public func deleteAndFetchIds(_ db: Database)
+    throws -> Set<RowDecoder.ID>
+    where RowDecoder: TableRecord & Identifiable,
+    RowDecoder.ID: Hashable & DatabaseValueConvertible & StatementColumnConvertible
+    {
+        let primaryKey = try db.primaryKey(RowDecoder.databaseTableName)
+        GRDBPrecondition(
+            primaryKey.columns.count == 1,
+            "Fetching id requires a single-column primary key in the table \(databaseTableName)")
+        
+        let statement = try deleteAndFetchStatement(db, selection: [Column(primaryKey.columns[0])])
+        
+        return try RowDecoder.ID.fetchSet(statement)
+    }
 #endif
 }
 
diff --git a/Tests/GRDBTests/TableRecordDeleteTests.swift b/Tests/GRDBTests/TableRecordDeleteTests.swift
index 88e9c81745..e45252a555 100644
--- a/Tests/GRDBTests/TableRecordDeleteTests.swift
+++ b/Tests/GRDBTests/TableRecordDeleteTests.swift
@@ -364,6 +364,30 @@ class TableRecordDeleteTests: GRDBTestCase {
         }
     }
     
+    @available(iOS 13, macOS 10.15, tvOS 13, watchOS 6, *) // Identifiable
+    func testRequestDeleteAndFetchIds() throws {
+#if GRDBCUSTOMSQLITE || GRDBCIPHER
+        guard sqlite3_libversion_number() >= 3035000 else {
+            throw XCTSkip("RETURNING clause is not available")
+        }
+#else
+        guard #available(iOS 15, macOS 12, tvOS 15, watchOS 8, *) else {
+            throw XCTSkip("RETURNING clause is not available")
+        }
+#endif
+        
+        let dbQueue = try makeDatabaseQueue()
+        try dbQueue.inDatabase { db in
+            try Person(id: 1, name: "Arthur", email: "arthur@example.com").insert(db)
+            try Person(id: 2, name: "Barbara", email: "barbara@example.com").insert(db)
+            try Person(id: 3, name: "Craig", email: "craig@example.com").insert(db)
+
+            let request = Person.filter(Column("id") != 2)
+            let deletedIds = try request.deleteAndFetchIds(db)
+            XCTAssertEqual(deletedIds, [1, 3])
+        }
+    }
+    
     func testJoinedRequestDeleteAll() throws {
         try makeDatabaseQueue().inDatabase { db in
             struct Player: MutablePersistableRecord {