Added TagWith support. (#160)

* Added TagWith support.

* Fixed XML doc.

* Switched to linq2db 3.4.2.

Author: sdanyliv

NuGet/linq2db.EntityFrameworkCore.nuspec

@@ -16,7 +16,7 @@
 		<dependencies>
 			<group targetFramework=".NETStandard2.1">
 				<dependency id="Microsoft.EntityFrameworkCore.Relational" version="5.0.2" />
-				<dependency id="linq2db" version="3.4.0" />
+				<dependency id="linq2db" version="3.4.2" />
 			</group>
 		</dependencies>
 	</metadata>

Source/LinqToDB.EntityFrameworkCore/Internal/LinqToDBForEFQueryProvider.cs

@@ -160,5 +160,14 @@ public IAsyncEnumerator<T> GetAsyncEnumerator(CancellationToken cancellationToke
 		{
 			return QueryProvider.ExecuteAsyncEnumerable<T>(Expression, cancellationToken).Result.GetAsyncEnumerator(cancellationToken);
 		}
+
+		/// <summary>
+		/// Returns generated SQL for specific LINQ query.
+		/// </summary>
+		/// <returns>Generated SQL.</returns>
+		public override string ToString()
+		{
+			return QueryProvider.ToString();
+		}
 	}
 }

Source/LinqToDB.EntityFrameworkCore/LinqToDBForEFToolsImplDefault.cs

@@ -558,6 +558,9 @@ public virtual MappingSchema GetMappingSchema(
 		static readonly MethodInfo ThenIncludeMethodInfo =
 			MemberHelper.MethodOfGeneric<IIncludableQueryable<object, object>>(q => q.ThenInclude<object, object, object>(null));
 
+		static readonly MethodInfo TagWithMethodInfo =
+			MemberHelper.MethodOfGeneric<IQueryable<object>>(q => q.TagWith(string.Empty));
+
 		static readonly MethodInfo ThenIncludeEnumerableMethodInfo =
 			MemberHelper.MethodOfGeneric<IIncludableQueryable<object, IEnumerable<object>>>(q => q.ThenInclude<object, object, object>(null));
 
@@ -580,6 +583,9 @@ static readonly MethodInfo
 
 		static readonly MethodInfo ToSql = MemberHelper.MethodOfGeneric(() => Sql.ToSql(1));
 
+		static readonly MethodInfo TagQueryMethodInfo =
+			MemberHelper.MethodOfGeneric<IQueryable<object>>(q => q.TagQuery(string.Empty));
+
 		/// <summary>
 		/// Removes conversions from expression.
 		/// </summary>
@@ -871,6 +877,14 @@ TransformInfo LocalTransform(Expression e)
 									// it is only one possible way now how to detect nested query. 
 									ignoreTracking = true;
 								}
+								else if (generic == TagWithMethodInfo)
+								{
+									var method =
+										TagQueryMethodInfo.MakeGenericMethod(methodCall.Method.GetGenericArguments());
+
+									return new TransformInfo(Expression.Call(method, methodCall.Arguments.Select(a => a.Transform(l => LocalTransform(l)))
+										.ToArray()), false, true);
+								}
 
 								if (isTunnel)
 									return new TransformInfo(methodCall.Arguments[0], false, true);

Source/LinqToDB.EntityFrameworkCore/linq2db.EntityFrameworkCore.csproj

@@ -23,7 +23,7 @@
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="linq2db" Version="3.4.0" />
+		<PackageReference Include="linq2db" Version="3.4.2" />
 		<PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="5.0.2" />
 		<PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0">
 			<PrivateAssets>all</PrivateAssets>

Tests/LinqToDB.EntityFrameworkCore.BaseTests/LinqToDB.EntityFrameworkCore.BaseTests.csproj

@@ -10,7 +10,7 @@
 
 	<ItemGroup>
 		<PackageReference Include="FluentAssertions" Version="5.10.3" />
-		<PackageReference Include="linq2db.Tools" Version="3.1.6" />
+		<PackageReference Include="linq2db.Tools" Version="3.4.2" />
 		<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="5.0.0" />
 		<PackageReference Include="Microsoft.Extensions.Logging" Version="5.0.0" />
 		<PackageReference Include="Microsoft.Extensions.Logging.Console" Version="5.0.0" />

Tests/LinqToDB.EntityFrameworkCore.SqlServer.Tests/ToolsTests.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Threading.Tasks;
+using FluentAssertions;
 using LinqToDB.Data;
 using LinqToDB.EntityFrameworkCore.BaseTests;
 using LinqToDB.EntityFrameworkCore.BaseTests.Models.Northwind;
@@ -816,5 +817,23 @@ RETURNS int
 				}
 			}
 		}
+
+		[Test]
+		public void TestTagWith([Values(true, false)] bool enableFilter)
+		{
+			using (var ctx = CreateContext(enableFilter))
+			{
+				var query = ctx.Employees.Include(e => e.ReportsToNavigation).TagWith("Tagged query");
+				var resultEF = query.ToArray();
+				var result = query.ToLinqToDB().ToArray();
+
+				var str = query.ToLinqToDB().ToString();
+
+				AreEqual(resultEF, result);
+
+				str.Should().Contain("Tagged query");
+			}
+		}
+
 	}
 }