Fixed ToRecordSet issue when query returns no records (should be empt…

…y RecordSet instead of null)
nreco · Jan 8, 2017 · 49364a3 · 49364a3
1 parent f58f92c
commit 49364a3
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Showing 4 changed files with 36 additions and 31 deletions.
diff --git a/src/NReco.Data.Tests/DbCommandBuilderTests.cs b/src/NReco.Data.Tests/DbCommandBuilderTests.cs
@@ -108,7 +108,7 @@ public void BuildCommands() {
 
 			// SELECT TEST with prefixes and expressions
 			IDbCommand cmd = cmdGenerator.GetSelectCommand( q );	
-			string masterSQL = "SELECT name,t.age,(t.age*12) as age_months FROM test t WHERE (((name LIKE @p0) Or (NOT(age>=@p1))) And ((weight=@p2) And (type IN (@p3,@p4)))) Or ((name<>@p5) And (type IS NOT NULL))";
+			string masterSQL = "SELECT name,t.age,t.age*12 as age_months FROM test t WHERE (((name LIKE @p0) Or (NOT(age>=@p1))) And ((weight=@p2) And (type IN (@p3,@p4)))) Or ((name<>@p5) And (type IS NOT NULL))";
 
 			Assert.Equal( masterSQL, cmd.CommandText.Trim() );
 
@@ -161,7 +161,7 @@ public void BuildCommands() {
 			// ------- escape identifiers asserts --------
 			dbFactory.IdentifierFormat = "[{0}]";
 			Assert.Equal( 
-				"SELECT [name],[t].[age],(t.age*12) as [age_months] FROM [test] [t] WHERE ((([name] LIKE @p0) Or (NOT([age]>=@p1))) And (([weight]=@p2) And ([type] IN (@p3,@p4)))) Or (([name]<>@p5) And ([type] IS NOT NULL))",	
+				"SELECT [name],[t].[age],t.age*12 as [age_months] FROM [test] [t] WHERE ((([name] LIKE @p0) Or (NOT([age]>=@p1))) And (([weight]=@p2) And ([type] IN (@p3,@p4)))) Or (([name]<>@p5) And ([type] IS NOT NULL))",	
 				cmdGenerator.GetSelectCommand( q ).CommandText.Trim() );
 			Assert.Equal(
 				"INSERT INTO [test] ([name],[age],[weight],[type]) VALUES (@p0,@p1,@p2,@p3)",
@@ -194,13 +194,13 @@ public void DataView() {
 
 			// simple count query test
 			Assert.Equal(
-				"SELECT (count(p.id)) as cnt FROM persons p LEFT JOIN countries c ON (c.id=p.country_id)",
+				"SELECT count(p.id) as cnt FROM persons p LEFT JOIN countries c ON (c.id=p.country_id)",
 				cmdGenerator.GetSelectCommand( new Query("persons_view").Select(QField.Count) ).CommandText.Trim()
 			);
 
 			// field mapping in select columns
 			Assert.Equal(
-				"SELECT (p.id) as id,name,(CASE WHEN DATEDIFF(dd, p.added_date, NOW() )>30 THEN 1 ELSE 0 END) as expired FROM persons p LEFT JOIN countries c ON (c.id=p.country_id)",
+				"SELECT p.id as id,name,CASE WHEN DATEDIFF(dd, p.added_date, NOW() )>30 THEN 1 ELSE 0 END as expired FROM persons p LEFT JOIN countries c ON (c.id=p.country_id)",
 				cmdGenerator.GetSelectCommand( new Query("persons_view")
 					.Select("id", "name", "expired") ).CommandText.Trim()
 			);

diff --git a/src/NReco.Data/DataHelper.cs b/src/NReco.Data/DataHelper.cs
@@ -70,16 +70,21 @@ internal static QNode MapQValue(QNode qNode, Func<IQueryValue,IQueryValue> mapFu
 			return qNode;
 		}
 
-		internal static void ExecuteReader(IDbCommand cmd, CommandBehavior cmdBehaviour, int recordOffset, int recordCount, Action<IDataReader> recordHandler) {
+		internal static void ExecuteReader<T>(
+			IDbCommand cmd, CommandBehavior cmdBehaviour, 
+			int recordOffset, int recordCount, 
+			IDataReaderResult<T> result) {
+
 			EnsureConnectionOpen(cmd.Connection, () => {
 				try {
 					using (var rdr = cmd.ExecuteReader(cmdBehaviour)) {
 						int index = 0;
 						int processed = 0;
+						result.Init(rdr);
 						while (rdr.Read() && processed < recordCount) {
 							if (index>=recordOffset) {
 								processed++;
-								recordHandler(rdr);
+								result.Read(rdr);
 							}
 							index++;
 						}
@@ -109,6 +114,8 @@ internal static async Task<T> ExecuteReaderAsync<T>(
 
 				int index = 0;
 				int processed = 0;
+
+				result.Init(rdr);
 				while ( (await rdr.ReadAsync(cancel)) && processed < recordCount) {
 					if (index>=recordOffset) {
 						processed++;

diff --git a/src/NReco.Data/Internal/DataReaderResult.cs b/src/NReco.Data/Internal/DataReaderResult.cs
@@ -24,6 +24,7 @@ namespace NReco.Data {
 
 	internal interface IDataReaderResult<T> {
 		T Result { get; }
+		void Init(IDataReader rdr);
 		void Read(IDataReader rdr);
 	}
 
@@ -37,6 +38,8 @@ internal SingleDataReaderResult(Func<IDataReader,T> convert) {
 			Result = default(T);
 		}
 
+		public void Init(IDataReader rdr) { }
+
 		public void Read(IDataReader rdr) {
 			Result = Convert(rdr);
 		}
@@ -52,6 +55,8 @@ internal ListDataReaderResult(Func<IDataReader,T> convert) {
 			Result = new List<T>();
 		}
 
+		public void Init(IDataReader rdr) { }
+
 		public void Read(IDataReader rdr) {
 			Result.Add( Convert(rdr) );
 		}
@@ -64,10 +69,13 @@ internal RecordSetDataReaderResult() {
 			Result = null;
 		}
 
-		public void Read(IDataReader rdr) {
+		public void Init(IDataReader rdr) {
 			if (Result==null) {
 				Result = DataHelper.GetRecordSetByReader(rdr);
-			}
+			}			
+		}
+
+		public void Read(IDataReader rdr) {
 			var rowValues = new object[rdr.FieldCount];
 			rdr.GetValues(rowValues);
 			Result.Add(rowValues).AcceptChanges();

diff --git a/src/NReco.Data/Internal/DbDataAdapter.SelectQuery.cs b/src/NReco.Data/Internal/DbDataAdapter.SelectQuery.cs
@@ -54,14 +54,11 @@ int DataReaderRecordOffset {
 			/// </summary>
 			/// <returns>depending on T, single value or all fields values from the first record</returns>
 			public T Single<T>() {
-				T result = default(T);
+				var res = new SingleDataReaderResult<T>( Read<T> );
 				using (var selectCmd = GetSelectCmd()) {
-					DataHelper.ExecuteReader(selectCmd, CommandBehavior.SingleRow, DataReaderRecordOffset, 1, 
-						(rdr) => {
-							result = Read<T>(rdr);
-						} );
+					DataHelper.ExecuteReader(selectCmd, CommandBehavior.SingleRow, DataReaderRecordOffset, 1, res);
 				}
-				return result;
+				return res.Result;
 			}
 
 			/// <summary>
@@ -90,14 +87,11 @@ public Task<T> SingleAsync<T>(CancellationToken cancel) {
 			/// </summary>
 			/// <returns>dictionary with field values or null if query returns zero records.</returns>
 			public Dictionary<string,object> ToDictionary() {
-				Dictionary<string,object> result = null;
+				var res = new SingleDataReaderResult<Dictionary<string,object>>( ReadDictionary );
 				using (var selectCmd = GetSelectCmd()) {
-					DataHelper.ExecuteReader(selectCmd, CommandBehavior.SingleRow, DataReaderRecordOffset, 1, 
-						(rdr) => {
-							result = ReadDictionary(rdr);
-						} );
+					DataHelper.ExecuteReader(selectCmd, CommandBehavior.SingleRow, DataReaderRecordOffset, 1, res);
 				}
-				return result;
+				return res.Result;
 			}
 
 			/// <summary>
@@ -150,14 +144,11 @@ public Task<List<Dictionary<string,object>>> ToDictionaryListAsync(CancellationT
 			/// </summary>
 			/// <returns>list with query results</returns>
 			public List<T> ToList<T>() {
-				var result = new List<T>();
+				var res = new ListDataReaderResult<T>( Read<T> );
 				using (var selectCmd = GetSelectCmd()) {
-					DataHelper.ExecuteReader(selectCmd, CommandBehavior.Default, DataReaderRecordOffset, RecordCount,
-						(rdr) => {
-							result.Add( Read<T>(rdr) );
-						} );
+					DataHelper.ExecuteReader(selectCmd, CommandBehavior.Default, DataReaderRecordOffset, RecordCount, res);
 				}
-				return result;
+				return res.Result;
 			}
 
 			/// <summary>
@@ -182,12 +173,11 @@ public Task<List<T>> ToListAsync<T>(CancellationToken cancel) {
 			/// Returns all query results as <see cref="RecordSet"/>.
 			/// </summary>
 			public RecordSet ToRecordSet() {
-				var result = new RecordSetDataReaderResult();
+				var res = new RecordSetDataReaderResult();
 				using (var selectCmd = GetSelectCmd()) {
-					DataHelper.ExecuteReader(selectCmd, CommandBehavior.Default, DataReaderRecordOffset, RecordCount,
-						result.Read );
+					DataHelper.ExecuteReader(selectCmd, CommandBehavior.Default, DataReaderRecordOffset, RecordCount, res);
 				}
-				return result.Result;
+				return res.Result;
 			}
 
 			/// <summary>
@@ -222,7 +212,7 @@ private Dictionary<string,object> ReadDictionary(IDataReader rdr) {
 			private T Read<T>(IDataReader rdr) {
 				var typeCode = Type.GetTypeCode(typeof(T));
 				// handle primitive single-value result
-				if (typeCode!=TypeCode.Object) {
+				if (typeCode!=TypeCode.Object || typeof(T)==typeof(object) ) {
 					if (rdr.FieldCount==1) {
 						return ChangeType<T>( rdr[0], typeCode);
 					} else if (rdr.FieldCount>1) {