Fix for #808

Add dynamic overloads for:
- QueryFirstAsync
- QueryFirstOrDefaultAsync
- QuerySingleAsync
- QuerySingleOrDefaultAsync

This may change a lot in 2.x, but many people asking for them now so here they are. Unit tests also fixed for QuerySingleOrDefaultAsync.

Note: this builds on the netstandard2 branch because of the xUnit changes to go with VS 2017 15.3.

Dapper.Tests/AsyncTests.cs

@@ -29,6 +29,13 @@ public async Task TestBasicStringUsageQueryFirstAsync()
             str.IsEqualTo("abc");
         }
 
+        [Fact]
+        public async Task TestBasicStringUsageQueryFirstAsyncDynamic()
+        {
+            var str = await connection.QueryFirstAsync("select 'abc' as [Value] union all select @txt", new { txt = "def" }).ConfigureAwait(false);
+            str.IsEqualTo("abc");
+        }
+
         [Fact]
         public async Task TestBasicStringUsageQueryFirstOrDefaultAsync()
         {
@@ -37,16 +44,37 @@ public async Task TestBasicStringUsageQueryFirstOrDefaultAsync()
         }
 
         [Fact]
-        public async Task TestBasicStringUsageQuerySingleAsync()
+        public async Task TestBasicStringUsageQueryFirstOrDefaultAsyncDynamic()
+        {
+            var str = await connection.QueryFirstOrDefaultAsync("select null as [Value] union all select @txt", new { txt = "def" }).ConfigureAwait(false);
+            str.IsNull();
+        }
+
+        [Fact]
+        public async Task TestBasicStringUsageQuerySingleAsyncDynamic()
         {
             var str = await connection.QuerySingleAsync<string>(new CommandDefinition("select 'abc' as [Value]")).ConfigureAwait(false);
             str.IsEqualTo("abc");
         }
 
+        [Fact]
+        public async Task TestBasicStringUsageQuerySingleAsync()
+        {
+            var str = await connection.QuerySingleAsync("select 'abc' as [Value]").ConfigureAwait(false);
+            str.IsEqualTo("abc");
+        }
+
         [Fact]
         public async Task TestBasicStringUsageQuerySingleOrDefaultAsync()
         {
-            var str = await connection.QuerySingleAsync<string>(new CommandDefinition("select null as [Value]")).ConfigureAwait(false);
+            var str = await connection.QuerySingleOrDefaultAsync<string>(new CommandDefinition("select null as [Value]")).ConfigureAwait(false);
+            str.IsNull();
+        }
+
+        [Fact]
+        public async Task TestBasicStringUsageQuerySingleOrDefaultAsyncDynamic()
+        {
+            var str = await connection.QuerySingleOrDefaultAsync("select null as [Value]").ConfigureAwait(false);
             str.IsNull();
         }
 

Dapper/SqlMapper.Async.cs

@@ -140,6 +140,54 @@ public static partial class SqlMapper
         public static Task<T> QuerySingleOrDefaultAsync<T>(this IDbConnection cnn, string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) =>
             QueryRowAsync<T>(cnn, Row.SingleOrDefault, typeof(T), new CommandDefinition(sql, param, transaction, commandTimeout, commandType, CommandFlags.None, default(CancellationToken)));
 
+        /// <summary>
+        /// Execute a single-row query asynchronously using .NET 4.5 Task.
+        /// </summary>
+        /// <param name="cnn">The connection to query on.</param>
+        /// <param name="sql">The SQL to execute for the query.</param>
+        /// <param name="param">The parameters to pass, if any.</param>
+        /// <param name="transaction">The transaction to use, if any.</param>
+        /// <param name="commandTimeout">The command timeout (in seconds).</param>
+        /// <param name="commandType">The type of command to execute.</param>
+        public static Task<dynamic> QueryFirstAsync(this IDbConnection cnn, string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) =>
+            QueryRowAsync<dynamic>(cnn, Row.First, typeof(DapperRow), new CommandDefinition(sql, param, transaction, commandTimeout, commandType, CommandFlags.None, default(CancellationToken)));
+
+        /// <summary>
+        /// Execute a single-row query asynchronously using .NET 4.5 Task.
+        /// </summary>
+        /// <param name="cnn">The connection to query on.</param>
+        /// <param name="sql">The SQL to execute for the query.</param>
+        /// <param name="param">The parameters to pass, if any.</param>
+        /// <param name="transaction">The transaction to use, if any.</param>
+        /// <param name="commandTimeout">The command timeout (in seconds).</param>
+        /// <param name="commandType">The type of command to execute.</param>
+        public static Task<dynamic> QueryFirstOrDefaultAsync(this IDbConnection cnn, string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) =>
+            QueryRowAsync<dynamic>(cnn, Row.FirstOrDefault, typeof(DapperRow), new CommandDefinition(sql, param, transaction, commandTimeout, commandType, CommandFlags.None, default(CancellationToken)));
+
+        /// <summary>
+        /// Execute a single-row query asynchronously using .NET 4.5 Task.
+        /// </summary>
+        /// <param name="cnn">The connection to query on.</param>
+        /// <param name="sql">The SQL to execute for the query.</param>
+        /// <param name="param">The parameters to pass, if any.</param>
+        /// <param name="transaction">The transaction to use, if any.</param>
+        /// <param name="commandTimeout">The command timeout (in seconds).</param>
+        /// <param name="commandType">The type of command to execute.</param>
+        public static Task<dynamic> QuerySingleAsync(this IDbConnection cnn, string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) =>
+            QueryRowAsync<dynamic>(cnn, Row.Single, typeof(DapperRow), new CommandDefinition(sql, param, transaction, commandTimeout, commandType, CommandFlags.None, default(CancellationToken)));
+
+        /// <summary>
+        /// Execute a single-row query asynchronously using .NET 4.5 Task.
+        /// </summary>
+        /// <param name="cnn">The connection to query on.</param>
+        /// <param name="sql">The SQL to execute for the query.</param>
+        /// <param name="param">The parameters to pass, if any.</param>
+        /// <param name="transaction">The transaction to use, if any.</param>
+        /// <param name="commandTimeout">The command timeout (in seconds).</param>
+        /// <param name="commandType">The type of command to execute.</param>
+        public static Task<dynamic> QuerySingleOrDefaultAsync(this IDbConnection cnn, string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) =>
+            QueryRowAsync<dynamic>(cnn, Row.SingleOrDefault, typeof(DapperRow), new CommandDefinition(sql, param, transaction, commandTimeout, commandType, CommandFlags.None, default(CancellationToken)));
+
         /// <summary>
         /// Execute a query asynchronously using .NET 4.5 Task.
         /// </summary>