Merge pull request #412 from StackExchange/QueryFirstOrDefault

Add {Query|Read}FirstOrDefault methods with optimized paths

Dapper.Contrib/SqlMapperExtensions.Async.cs

@@ -78,7 +78,7 @@ public static partial class SqlMapperExtensions
         /// <param name="transaction">The transaction to run under, null (the defualt) if none</param>
         /// <param name="commandTimeout">Number of seconds before command execution timeout</param>
         /// <returns>Entity of T</returns>
-        public static async Task<IEnumerable<T>> GetAllAsync<T>(this IDbConnection connection, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
+        public static Task<IEnumerable<T>> GetAllAsync<T>(this IDbConnection connection, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
         {
             var type = typeof(T);
             var cacheType = typeof(List<T>);
@@ -95,9 +95,12 @@ public static partial class SqlMapperExtensions
 
             if (!type.IsInterface())
             {
-                return await connection.QueryAsync<T>(sql, null, transaction, commandTimeout);
+                return connection.QueryAsync<T>(sql, null, transaction, commandTimeout);
             }
-
+            return GetAllAsyncImpl<T>(connection, transaction, commandTimeout, sql, type);
+        }
+        private static async Task<IEnumerable<T>> GetAllAsyncImpl<T>(IDbConnection connection, IDbTransaction transaction, int? commandTimeout, string sql, Type type) where T : class
+        {
             var result = await connection.QueryAsync(sql);
             var list = new List<T>();
             foreach (IDictionary<string, object> res in result)
@@ -124,7 +127,7 @@ public static partial class SqlMapperExtensions
         /// <param name="commandTimeout">Number of seconds before command execution timeout</param>
         /// <param name="sqlAdapter">The specific ISqlAdapter to use, auto-detected based on connection if null</param>
         /// <returns>Identity of inserted entity</returns>
-        public static async Task<int> InsertAsync<T>(this IDbConnection connection, T entityToInsert, IDbTransaction transaction = null,
+        public static Task<int> InsertAsync<T>(this IDbConnection connection, T entityToInsert, IDbTransaction transaction = null,
             int? commandTimeout = null, ISqlAdapter sqlAdapter = null) where T : class
         {
             var type = typeof(T);
@@ -164,13 +167,13 @@ public static partial class SqlMapperExtensions
 
             if (!isList)    //single entity
             {
-                return await sqlAdapter.InsertAsync(connection, transaction, commandTimeout, name, sbColumnList.ToString(),
+                return sqlAdapter.InsertAsync(connection, transaction, commandTimeout, name, sbColumnList.ToString(),
                     sbParameterList.ToString(), keyProperties, entityToInsert);
             }
 
             //insert list of entities
             var cmd = $"INSERT INTO {name} ({sbColumnList}) values ({sbParameterList})";
-            return await connection.ExecuteAsync(cmd, entityToInsert, transaction, commandTimeout);
+            return connection.ExecuteAsync(cmd, entityToInsert, transaction, commandTimeout);
         }
 
         /// <summary>

Dapper.StrongName/project.json

@@ -5,7 +5,7 @@
   "licenseUrl": "http://www.apache.org/licenses/LICENSE-2.0",
   "summary": "A high performance Micro-ORM",
   "description": "A high performance Micro-ORM supporting SQL Server, MySQL, Sqlite, SqlCE, Firebird etc..",
-  "version": "1.50-beta3",
+  "version": "1.50-beta4",
   "title": "Dapper dot net (strong named)",
   "tags": [ "orm", "sql", "micro-orm" ],
   "copyright": "2015 Stack Exchange, Inc.",

Dapper.Tests/PerformanceTests.cs

@@ -130,10 +130,13 @@ public void Run(int iterations)
                 var mapperConnection = TestSuite.GetOpenConnection();
                 tests.Add(id => mapperConnection.Query<Post>("select * from Posts where Id = @Id", new { Id = id }, buffered: true).First(), "Mapper Query (buffered)");
                 tests.Add(id => mapperConnection.Query<Post>("select * from Posts where Id = @Id", new { Id = id }, buffered: false).First(), "Mapper Query (non-buffered)");
+                tests.Add(id => mapperConnection.QueryFirstOrDefault<Post>("select * from Posts where Id = @Id", new { Id = id }), "Mapper QueryFirstOrDefault");
+
 
                 var mapperConnection2 = TestSuite.GetOpenConnection();
                 tests.Add(id => mapperConnection2.Query("select * from Posts where Id = @Id", new { Id = id }, buffered: true).First(), "Dynamic Mapper Query (buffered)");
                 tests.Add(id => mapperConnection2.Query("select * from Posts where Id = @Id", new { Id = id }, buffered: false).First(), "Dynamic Mapper Query (non-buffered)");
+                tests.Add(id => mapperConnection2.QueryFirstOrDefault("select * from Posts where Id = @Id", new { Id = id }), "Dynamic Mapper QueryQueryFirstOrDefault");
 
                 // dapper.contrib
                 var mapperConnection3 = TestSuite.GetOpenConnection();

Dapper.Tests/Tests.Async.cs

@@ -156,6 +156,19 @@ public async Task TestMultiAsync()
             }
         }
 
+        [Fact]
+        public async Task TestMultiAsyncViaFirstOrDefault()
+        {
+            using (SqlMapper.GridReader multi = await connection.QueryMultipleAsync("select 1; select 2; select 3; select 4; select 5"))
+            {
+                multi.ReadFirstOrDefaultAsync<int>().Result.IsEqualTo(1);
+                multi.ReadAsync<int>().Result.Single().IsEqualTo(2);
+                multi.ReadFirstOrDefaultAsync<int>().Result.IsEqualTo(3);
+                multi.ReadAsync<int>().Result.Single().IsEqualTo(4);
+                multi.ReadFirstOrDefaultAsync<int>().Result.IsEqualTo(5);
+            }
+        }
+
         [Fact]
         public async Task TestMultiClosedConnAsync()
         {
@@ -166,6 +179,19 @@ public async Task TestMultiClosedConnAsync()
             }
         }
 
+        [Fact]
+        public async Task TestMultiClosedConnAsyncViaFirstOrDefault()
+        {
+            using (SqlMapper.GridReader multi = await connection.QueryMultipleAsync("select 1; select 2; select 3; select 4; select 5;"))
+            {
+                multi.ReadFirstOrDefaultAsync<int>().Result.IsEqualTo(1);
+                multi.ReadAsync<int>().Result.Single().IsEqualTo(2);
+                multi.ReadFirstOrDefaultAsync<int>().Result.IsEqualTo(3);
+                multi.ReadAsync<int>().Result.Single().IsEqualTo(4);
+                multi.ReadFirstOrDefaultAsync<int>().Result.IsEqualTo(5);
+            }
+        }
+
 #if EXTERNALS
         [Fact]
         public async Task ExecuteReaderOpenAsync()
@@ -337,6 +363,19 @@ public async Task TypeBasedViaTypeAsync()
             b.IsEqualTo("abc");
         }
 
+        [Fact]
+        public async Task TypeBasedViaTypeAsyncFirstOrDefault()
+        {
+            Type type = GetSomeType();
+
+            dynamic actual = (await marsConnection.QueryFirstOrDefaultAsync(type, "select @A as [A], @B as [B]", new { A = 123, B = "abc" }));
+            ((object)actual).GetType().IsEqualTo(type);
+            int a = actual.A;
+            string b = actual.B;
+            a.IsEqualTo(123);
+            b.IsEqualTo("abc");
+        }
+
         [Fact]
         public async Task Issue22_ExecuteScalarAsync()
         {
@@ -562,7 +601,26 @@ public async Task TestSubsequentQueriesSuccessAsync()
         class AsyncFoo0 { public int Id { get; set; } }
         class AsyncFoo1 { public int Id { get; set; } }
         class AsyncFoo2 { public int Id { get; set; } }
-        
+
+        [Fact]
+        public async Task TestSchemaChangedViaFirstOrDefaultAsync()
+        {
+            await connection.ExecuteAsync("create table #dog(Age int, Name nvarchar(max)) insert #dog values(1, 'Alf')");
+            try
+            {
+                var d = await connection.QueryFirstOrDefaultAsync<Dog>("select * from #dog");
+                d.Name.IsEqualTo("Alf");
+                d.Age.IsEqualTo(1);
+                connection.Execute("alter table #dog drop column Name");
+                d = await connection.QueryFirstOrDefaultAsync<Dog>("select * from #dog");
+                d.Name.IsNull();
+                d.Age.IsEqualTo(1);
+            }
+            finally
+            {
+                await connection.ExecuteAsync("drop table #dog");
+            }
+        }
 
         [Fact]
         public async Task TestMultiMapArbitraryMapsAsync()

Dapper.Tests/Tests.cs

@@ -258,6 +258,26 @@ public void TestSchemaChanged()
             }
         }
 
+        [Fact]
+        public void TestSchemaChangedViaFirstOrDefault()
+        {
+            connection.Execute("create table #dog(Age int, Name nvarchar(max)) insert #dog values(1, 'Alf')");
+            try
+            {
+                var d = connection.QueryFirstOrDefault<Dog>("select * from #dog");
+                d.Name.IsEqualTo("Alf");
+                d.Age.IsEqualTo(1);
+                connection.Execute("alter table #dog drop column Name");
+                d = connection.QueryFirstOrDefault<Dog>("select * from #dog");
+                d.Name.IsNull();
+                d.Age.IsEqualTo(1);
+            }
+            finally
+            {
+                connection.Execute("drop table #dog");
+            }
+        }
+
         [Fact]
         public void TestSchemaChangedMultiMap()
         {
@@ -845,6 +865,8 @@ public void TestFastExpandoSupportsIDictionary()
         public void TestDapperSetsPrivates()
         {
             connection.Query<PrivateDan>("select 'one' ShadowInDB").First().Shadow.IsEqualTo(1);
+
+            connection.QueryFirstOrDefault<PrivateDan>("select 'one' ShadowInDB").Shadow.IsEqualTo(1);
         }
 
         class PrivateDan
@@ -1631,6 +1653,25 @@ public void TestChangingDefaultStringTypeMappingToAnsiString()
             Dapper.SqlMapper.AddTypeMap(typeof(string), DbType.String);  // Restore Default to Unicode String
         }
 
+        [Fact]
+        public void TestChangingDefaultStringTypeMappingToAnsiStringFirstOrDefault()
+        {
+            var sql = "SELECT SQL_VARIANT_PROPERTY(CONVERT(sql_variant, @testParam),'BaseType') AS BaseType";
+            var param = new { testParam = "TestString" };
+
+            var result01 = connection.QueryFirstOrDefault<string>(sql, param);
+            result01.IsEqualTo("nvarchar");
+
+            Dapper.SqlMapper.PurgeQueryCache();
+
+            Dapper.SqlMapper.AddTypeMap(typeof(string), DbType.AnsiString);   // Change Default String Handling to AnsiString
+            var result02 = connection.QueryFirstOrDefault<string>(sql, param);
+            result02.IsEqualTo("varchar");
+
+            Dapper.SqlMapper.PurgeQueryCache();
+            Dapper.SqlMapper.AddTypeMap(typeof(string), DbType.String);  // Restore Default to Unicode String
+        }
+
 #if COREFX
         class TransactedConnection : IDbConnection
         {

Dapper/SqlMapper.GridReader.Async.cs

@@ -32,6 +32,15 @@ public Task<IEnumerable<dynamic>> ReadAsync(bool buffered = true)
                 return ReadAsyncImpl<dynamic>(typeof(DapperRow), buffered);
             }
 
+            /// <summary>
+            /// Read the first row of the next grid of results, returned as a dynamic object
+            /// </summary>
+            /// <remarks>Note: the row can be accessed via "dynamic", or by casting to an IDictionary&lt;string,object&gt;</remarks>
+            public Task<dynamic> ReadFirstOrDefaultAsync()
+            {
+                return ReadFirstOrDefaultAsyncImpl<dynamic>(typeof(DapperRow));
+            }
+
             /// <summary>
             /// Read the next grid of results
             /// </summary>
@@ -40,6 +49,16 @@ public Task<IEnumerable<object>> ReadAsync(Type type, bool buffered = true)
                 if (type == null) throw new ArgumentNullException(nameof(type));
                 return ReadAsyncImpl<object>(type, buffered);
             }
+
+            /// <summary>
+            /// Read the first row of the next grid of results
+            /// </summary>
+            public Task<object> ReadFirstOrDefaultAsync(Type type)
+            {
+                if (type == null) throw new ArgumentNullException(nameof(type));
+                return ReadFirstOrDefaultAsyncImpl<object>(type);
+            }
+
             /// <summary>
             /// Read the next grid of results
             /// </summary>
@@ -48,6 +67,14 @@ public Task<IEnumerable<T>> ReadAsync<T>(bool buffered = true)
                 return ReadAsyncImpl<T>(typeof(T), buffered);
             }
 
+            /// <summary>
+            /// Read the first row of the next grid of results
+            /// </summary>
+            public Task<T> ReadFirstOrDefaultAsync<T>()
+            {
+                return ReadFirstOrDefaultAsyncImpl<T>(typeof(T));
+            }
+
             private async Task NextResultAsync()
             {
                 if (await ((DbDataReader)reader).NextResultAsync(cancel).ConfigureAwait(false))
@@ -94,6 +121,42 @@ private Task<IEnumerable<T>> ReadAsyncImpl<T>(Type type, bool buffered)
                 }
             }
 
+            private Task<T> ReadFirstOrDefaultAsyncImpl<T>(Type type)
+            {
+                var dbReader = reader as DbDataReader;
+                if (dbReader != null) return ReadFirstOrDefaultAsyncImplImpl<T>(dbReader, type);
+
+                // no async API available; use non-async and fake it
+                return Task.FromResult<T>(ReadFirstOrDefaultImpl<T>(type));
+            }
+
+            private async Task<T> ReadFirstOrDefaultAsyncImplImpl<T>(DbDataReader reader, Type type)
+            {
+                if (reader == null) throw new ObjectDisposedException(GetType().FullName, "The reader has been disposed; this can happen after all data has been consumed");
+                if (IsConsumed) throw new InvalidOperationException("Query results must be consumed in the correct order, and each result can only be consumed once");
+
+                IsConsumed = true;
+                T result = default(T);
+                if (await reader.ReadAsync(cancel).ConfigureAwait(false))
+                {
+                    var typedIdentity = identity.ForGrid(type, gridIndex);
+                    CacheInfo cache = GetCacheInfo(typedIdentity, null, addToCache);
+                    var deserializer = cache.Deserializer;
+
+                    int hash = GetColumnHash(reader);
+                    if (deserializer.Func == null || deserializer.Hash != hash)
+                    {
+                        deserializer = new DeserializerState(hash, GetDeserializer(type, reader, 0, -1, false));
+                        cache.Deserializer = deserializer;
+                    }
+                    result = (T)deserializer.Func(reader);
+
+                    while (await reader.ReadAsync(cancel).ConfigureAwait(false)) { }
+                }
+                await NextResultAsync().ConfigureAwait(false);
+                return result;
+            }
+
             private async Task<IEnumerable<T>> ReadBufferedAsync<T>(int index, Func<IDataReader, object> deserializer, Identity typedIdentity)
             {
                 try

Dapper/SqlMapper.GridReader.cs

@@ -39,6 +39,15 @@ public IEnumerable<dynamic> Read(bool buffered = true)
                 return ReadImpl<dynamic>(typeof(DapperRow), buffered);
             }
 
+            /// <summary>
+            /// Read the first row of the next grid of results, returned as a dynamic object
+            /// </summary>
+            /// <remarks>Note: the row can be accessed via "dynamic", or by casting to an IDictionary&lt;string,object&gt;</remarks>
+            public dynamic ReadFirstOrDefault()
+            {
+                return ReadFirstOrDefaultImpl<dynamic>(typeof(DapperRow));
+            }
+
             /// <summary>
             /// Read the next grid of results
             /// </summary>
@@ -47,6 +56,14 @@ public IEnumerable<T> Read<T>(bool buffered = true)
                 return ReadImpl<T>(typeof(T), buffered);
             }
 
+            /// <summary>
+            /// Read the first row of the next grid of results
+            /// </summary>
+            public T ReadFirstOrDefault<T>()
+            {
+                return ReadFirstOrDefaultImpl<T>(typeof(T));
+            }
+
             /// <summary>
             /// Read the next grid of results
             /// </summary>
@@ -56,6 +73,15 @@ public IEnumerable<object> Read(Type type, bool buffered = true)
                 return ReadImpl<object>(type, buffered);
             }
 
+            /// <summary>
+            /// Read the first row of the next grid of results
+            /// </summary>
+            public object ReadFirstOrDefault(Type type)
+            {
+                if (type == null) throw new ArgumentNullException(nameof(type));
+                return ReadFirstOrDefaultImpl<object>(type);
+            }
+
             private IEnumerable<T> ReadImpl<T>(Type type, bool buffered)
             {
                 if (reader == null) throw new ObjectDisposedException(GetType().FullName, "The reader has been disposed; this can happen after all data has been consumed");
@@ -75,6 +101,32 @@ private IEnumerable<T> ReadImpl<T>(Type type, bool buffered)
                 return buffered ? result.ToList() : result;
             }
 
+            private T ReadFirstOrDefaultImpl<T>(Type type)
+            {
+                if (reader == null) throw new ObjectDisposedException(GetType().FullName, "The reader has been disposed; this can happen after all data has been consumed");
+                if (IsConsumed) throw new InvalidOperationException("Query results must be consumed in the correct order, and each result can only be consumed once");
+                IsConsumed = true;
+
+                T result = default(T);
+                if(reader.Read())
+                {
+                    var typedIdentity = identity.ForGrid(type, gridIndex);
+                    CacheInfo cache = GetCacheInfo(typedIdentity, null, addToCache);
+                    var deserializer = cache.Deserializer;
+
+                    int hash = GetColumnHash(reader);
+                    if (deserializer.Func == null || deserializer.Hash != hash)
+                    {
+                        deserializer = new DeserializerState(hash, GetDeserializer(type, reader, 0, -1, false));
+                        cache.Deserializer = deserializer;
+                    }
+                    result = (T) deserializer.Func(reader);
+                    while (reader.Read()) { }
+                }
+                NextResult();
+                return result;
+            }
+
 
             private IEnumerable<TReturn> MultiReadInternal<TFirst, TSecond, TThird, TFourth, TFifth, TSixth, TSeventh, TReturn>(Delegate func, string splitOn)
             {

Dapper/project.json

@@ -5,7 +5,7 @@
   "licenseUrl": "http://www.apache.org/licenses/LICENSE-2.0",
   "summary": "A high performance Micro-ORM",
   "description": "A high performance Micro-ORM supporting SQL Server, MySQL, Sqlite, SqlCE, Firebird etc..",
-  "version": "1.50-beta3",
+  "version": "1.50-beta4",
   "title": "Dapper dot net",
   "tags": [ "orm", "sql", "micro-orm" ],
   "copyright": "2015 Stack Exchange, Inc.",