Raise a fatal error when the users filters a database view by primary…

… key

Fixes #1648

GRDB/Core/Database+Schema.swift

@@ -359,6 +359,36 @@ extension Database {
         throw DatabaseError.noSuchTable(tableName)
     }
 
+    /// Returns the name of the single-column primary key.
+    ///
+    /// A fatal error is raised if the primary key has several columns, or
+    /// if `tableName` is the name of a database view.
+    func filteringPrimaryKeyColumn(_ tableName: String) throws -> String {
+        do {
+            let primaryKey = try primaryKey(tableName)
+            GRDBPrecondition(
+                primaryKey.columns.count == 1,
+                "Filtering by primary key requires a single-column primary key in the table '\(tableName)'")
+            return primaryKey.columns[0]
+        } catch let error as DatabaseError {
+            // Maybe the user tries to filter a view by primary key,
+            // as in <https://github.com/groue/GRDB.swift/issues/1648>.
+            // In this case, raise a fatalError because this is a
+            // programmer error which is very likely to be detected
+            // during development.
+            if case .SQLITE_ERROR = error.resultCode,
+               (try? viewExists(tableName)) == true
+            {
+                fatalError("""
+                    Filtering by primary key is not available on the database view '\(tableName)'. \
+                    Use `filter(Column("...") == value)` instead.
+                    """)
+            } else {
+                throw error
+            }
+        }
+    }
+
     /// Returns nil if table does not exist
     private func primaryKey(_ table: TableIdentifier) throws -> PrimaryKeyInfo? {
         SchedulingWatchdog.preconditionValidQueue(self)

GRDB/QueryInterface/Request/RequestProtocols.swift

@@ -458,11 +458,7 @@ extension TableRequest where Self: FilteredRequest, Self: TypedRequest {
                 }
 
                 return filterWhenConnected(keys: { [databaseTableName] db in
-                    let primaryKey = try db.primaryKey(databaseTableName)
-                    GRDBPrecondition(
-                        primaryKey.columns.count == 1,
-                        "Requesting by key requires a single-column primary key in the table \(databaseTableName)")
-                    let column = primaryKey.columns[0]
+                    let column = try db.filteringPrimaryKeyColumn(databaseTableName)
                     let strategy = recordType.databaseDataEncodingStrategy(for: column)
                     let expressions = try datas.map { try strategy.encode($0).sqlExpression }
                     return expressions
@@ -475,11 +471,7 @@ extension TableRequest where Self: FilteredRequest, Self: TypedRequest {
                 }
 
                 return filterWhenConnected(keys: { [databaseTableName] db in
-                    let primaryKey = try db.primaryKey(databaseTableName)
-                    GRDBPrecondition(
-                        primaryKey.columns.count == 1,
-                        "Requesting by key requires a single-column primary key in the table \(databaseTableName)")
-                    let column = primaryKey.columns[0]
+                    let column = try db.filteringPrimaryKeyColumn(databaseTableName)
                     let strategy = recordType.databaseDateEncodingStrategy(for: column)
                     let expressions = dates.map { strategy.encode($0).sqlExpression }
                     return expressions
@@ -492,11 +484,7 @@ extension TableRequest where Self: FilteredRequest, Self: TypedRequest {
                 }
 
                 return filterWhenConnected(keys: { [databaseTableName] db in
-                    let primaryKey = try db.primaryKey(databaseTableName)
-                    GRDBPrecondition(
-                        primaryKey.columns.count == 1,
-                        "Requesting by key requires a single-column primary key in the table \(databaseTableName)")
-                    let column = primaryKey.columns[0]
+                    let column = try db.filteringPrimaryKeyColumn(databaseTableName)
                     let strategy = recordType.databaseUUIDEncodingStrategy(for: column)
                     let expressions = uuids.map { strategy.encode($0).sqlExpression }
                     return expressions
@@ -524,12 +512,8 @@ extension TableRequest where Self: FilteredRequest, Self: TypedRequest {
             // Don't bother removing NULLs. We'd lose CPU cycles, and this does not
             // change the SQLite results anyway.
             let expressions = try keys(db)
-
-            let primaryKey = try db.primaryKey(databaseTableName)
-            GRDBPrecondition(
-                primaryKey.columns.count == 1,
-                "Requesting by key requires a single-column primary key in the table \(databaseTableName)")
-            return SQLCollection.array(expressions).contains(Column(primaryKey.columns[0]).sqlExpression)
+            let column = try db.filteringPrimaryKeyColumn(databaseTableName)
+            return SQLCollection.array(expressions).contains(Column(column).sqlExpression)
         }
     }
 

GRDB/Record/TableRecord.swift

@@ -744,13 +744,10 @@ extension TableRecord {
     ///   any error that prevented the `RecordError` from being constructed.
     public static func recordNotFound(_ db: Database, key: some DatabaseValueConvertible) -> any Error {
         do {
-            let primaryKey = try db.primaryKey(databaseTableName)
-            GRDBPrecondition(
-                primaryKey.columns.count == 1,
-                "Requesting by key requires a single-column primary key in the table \(databaseTableName)")
+            let column = try db.filteringPrimaryKeyColumn(databaseTableName)
             return RecordError.recordNotFound(
                 databaseTableName: databaseTableName,
-                key: [primaryKey.columns[0]: key.databaseValue])
+                key: [column: key.databaseValue])
         } catch {
             return error
         }