Added informative message for preventing usage of non relational providers.

Author: sdanyliv

Source/LinqToDB.EntityFrameworkCore/LinqToDBForEFToolsImplDefault.cs

@@ -728,13 +728,15 @@ public virtual DbContext GetCurrentContext(IQueryable query)
 			var queryContextFactoryField = compiler.GetType().GetField("_queryContextFactory", BindingFlags.NonPublic | BindingFlags.Instance);
 
 			if (queryContextFactoryField == null)
-				throw new LinqToDBForEFToolsException($"Can not find private field '{compiler.GetType()}._queryContextFactory' in current EFCore Version");
+				throw new LinqToDBForEFToolsException($"Can not find private field '{compiler.GetType()}._queryContextFactory' in current EFCore Version.");
+
+			if (!(queryContextFactoryField.GetValue(compiler) is RelationalQueryContextFactory queryContextFactory))
+				throw new LinqToDBForEFToolsException("LinqToDB Tools for EFCore support only Relational Databases.");
 
-			var queryContextFactory  = (RelationalQueryContextFactory) queryContextFactoryField.GetValue(compiler);	    
 			var dependenciesProperty = typeof(RelationalQueryContextFactory).GetProperty("Dependencies", BindingFlags.NonPublic | BindingFlags.Instance);
 
 			if (queryContextFactoryField == null)
-				throw new LinqToDBForEFToolsException($"Can not find private property '{nameof(RelationalQueryContextFactory)}.Dependencies' in current EFCore Version");
+				throw new LinqToDBForEFToolsException($"Can not find private property '{nameof(RelationalQueryContextFactory)}.Dependencies' in current EFCore Version.");
 
 			var dependencies = (QueryContextDependencies) dependenciesProperty.GetValue(queryContextFactory);
 

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

@@ -7,6 +7,7 @@
 	<ItemGroup>
 		<PackageReference Include="JetBrains.DotMemoryUnit" Version="3.0.20171219.105559" />
 		<PackageReference Include="linq2db.MySql" Version="2.0.0-beta5" />
+		<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="2.1.1" />
 		<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.0-rc1-final" />
 		<PackageReference Include="Microsoft.Extensions.Logging.Console" Version="2.1.0-rc1-final" />
 		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.0" />

Tests/LinqToDB.EntityFrameworkCore.Tests/ToolsTests.cs

@@ -18,6 +18,7 @@ namespace LinqToDB.EntityFrameworkCore.Tests
 	public class ToolsTests : TestsBase
 	{
 		private readonly DbContextOptions _options;
+		private DbContextOptions<AdventureWorksContext> _inmemoryOptions;
 
 		static ToolsTests()
 		{
@@ -34,6 +35,21 @@ public ToolsTests()
 			optionsBuilder.UseLoggerFactory(TestUtils.LoggerFactory);
 
 			_options = optionsBuilder.Options;
+
+			optionsBuilder = new DbContextOptionsBuilder<AdventureWorksContext>();
+			//new SqlServerDbContextOptionsBuilder(optionsBuilder);
+
+			optionsBuilder.UseInMemoryDatabase();
+			optionsBuilder.UseLoggerFactory(TestUtils.LoggerFactory);
+
+			_inmemoryOptions = optionsBuilder.Options;
+		}
+
+		private AdventureWorksContext CreateAdventureWorksContextInMemory()
+		{
+			var ctx = new AdventureWorksContext(_inmemoryOptions);
+			ctx.Database.EnsureCreated();
+			return ctx;
 		}
 
 		private AdventureWorksContext CreateAdventureWorksContext()
@@ -493,6 +509,42 @@ public async Task TestIncludeMany()
 
 		}
 
+		[Test]
+		public async Task TestInMemory()
+		{
+			using (var ctx = CreateAdventureWorksContextInMemory())
+			{
+				Assert.Throws<LinqToDBForEFToolsException>(() =>
+				{
+					ctx.SalesOrders.ToLinqToDB().ToArray();
+				});
+
+				Assert.Throws<LinqToDBForEFToolsException>(() =>
+				{
+					var query = ctx.SalesOrders
+						.Where(so => so.CustomerID == -1)
+						.Delete();
+				});
+			}
+		}
+
+		[Test]
+		public async Task TestContinuousQueries()
+		{
+			Common.Configuration.Linq.AllowMultipleQuery = true;
+
+			using (var ctx = CreateAdventureWorksContext())
+			{
+				var query = ctx.SalesOrders
+					.Include(o => o.Details)
+					.ThenInclude(d => d.SalesOrder);
+
+				var expected = await query.ToLinqToDB().ToArrayAsync();
+				var result = await query.ToLinqToDB().ToArrayAsync();
+			}
+
+		}
+
 
 	}
 }