Custom CreateCommand method. Resolves DapperLib#2127

This allows the user to provide their own IDbCommand to be used by Dapper internally.

Author: billrob

Dapper/CommandDefinition.cs

@@ -66,6 +66,11 @@ internal void OnCompleted()
         /// </summary>
         public CommandFlags Flags { get; }
 
+        /// <summary>
+        /// The create Func that will be used to create the IDbCommand.  When null the connection.CreateCommand() will be used.
+        /// </summary>
+        internal Func<IDbConnection, IDbCommand>? CreateCommand { get; }
+
         /// <summary>
         /// Can async queries be pipelined?
         /// </summary>
@@ -95,6 +100,26 @@ public CommandDefinition(string commandText, object? parameters = null, IDbTrans
             CancellationToken = cancellationToken;
         }
 
+        /// <summary>
+        /// Initialize the command definition
+        /// </summary>
+        /// <param name="commandText">The text for this command.</param>
+        /// <param name="createCommand">The a custom way to create a IDbCommand object.  This is to override the default connection.CreateCommand() behavior.</param>
+        /// <param name="parameters">The parameters for this command.</param>
+        /// <param name="transaction">The transaction for this command to participate in.</param>
+        /// <param name="commandTimeout">The timeout (in seconds) for this command.</param>
+        /// <param name="commandType">The <see cref="CommandType"/> for this command.</param>
+        /// <param name="flags">The behavior flags for this command.</param>
+        /// <param name="cancellationToken">The cancellation token for this command.</param>
+        public CommandDefinition(string commandText, Func<IDbConnection, IDbCommand> createCommand, object? parameters = null, IDbTransaction? transaction = null,
+                                int? commandTimeout = null, CommandType? commandType = null, CommandFlags flags = CommandFlags.Buffered
+                                 , CancellationToken cancellationToken = default
+            )
+                : this(commandText, parameters, transaction, commandTimeout, commandType, flags, cancellationToken)
+        {
+            CreateCommand = createCommand;
+        }
+
         internal static CommandType InferCommandType(string sql)
         {
             // if the sql contains any whitespace character (space/tab/cr/lf/etc - via unicode),
@@ -120,7 +145,12 @@ private CommandDefinition(object? parameters, CommandFlags flags) : this()
 
         internal IDbCommand SetupCommand(IDbConnection cnn, Action<IDbCommand, object?>? paramReader)
         {
-            var cmd = cnn.CreateCommand();
+            IDbCommand cmd;
+            if (CreateCommand == null)
+                cmd = cnn.CreateCommand();
+            else
+                cmd = CreateCommand(cnn);
+
             var init = GetInit(cmd.GetType());
             init?.Invoke(cmd);
             if (Transaction is not null)

Dapper/PublicAPI.Shipped.txt

@@ -9,6 +9,7 @@ Dapper.CommandDefinition.Buffered.get -> bool
 Dapper.CommandDefinition.CancellationToken.get -> System.Threading.CancellationToken
 Dapper.CommandDefinition.CommandDefinition() -> void
 Dapper.CommandDefinition.CommandDefinition(string! commandText, object? parameters = null, System.Data.IDbTransaction? transaction = null, int? commandTimeout = null, System.Data.CommandType? commandType = null, Dapper.CommandFlags flags = Dapper.CommandFlags.Buffered, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> void
+Dapper.CommandDefinition.CommandDefinition(string! commandText, System.Func<System.Data.IDbConnection!, System.Data.IDbCommand!>! createCommand, object? parameters = null, System.Data.IDbTransaction? transaction = null, int? commandTimeout = null, System.Data.CommandType? commandType = null, Dapper.CommandFlags flags = Dapper.CommandFlags.Buffered, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> void
 Dapper.CommandDefinition.CommandText.get -> string!
 Dapper.CommandDefinition.CommandTimeout.get -> int?
 Dapper.CommandDefinition.CommandType.get -> System.Data.CommandType?

tests/Dapper.Tests/MiscTests.cs

@@ -1394,5 +1394,22 @@ public void SetDynamicProperty_WithValueType_Succeeds()
             obj.NewProperty = true;
             Assert.True(obj.NewProperty);
         }
+
+        [Fact]
+        public void TestCreateCommandCalled()
+        {
+            var customCreateCommandCalled = false;
+            var createCommand = new Func<IDbConnection, IDbCommand>(conn =>
+            {
+                customCreateCommandCalled = true;
+                return conn.CreateCommand();
+            });
+
+            var definition = new CommandDefinition("select 1", createCommand);
+
+            connection.Query<int>(definition);
+
+            Assert.True(customCreateCommandCalled);
+        }
     }
 }