ToString() on string columns added (#29349)

Fixes #20839

Author: bikbov

src/EFCore.SqlServer/Query/Internal/SqlServerObjectToStringTranslator.cs

@@ -67,6 +67,11 @@ public SqlServerObjectToStringTranslator(ISqlExpressionFactory sqlExpressionFact
             return null;
         }
 
+        if(instance.TypeMapping is not null && instance.TypeMapping.ClrType == typeof(string))
+        {
+            return instance;
+        }
+
         if (instance.Type == typeof(bool))
         {
             if (instance is ColumnExpression columnExpression && columnExpression.IsNullable)

src/EFCore.Sqlite.Core/Query/Internal/SqliteObjectToStringTranslator.cs

@@ -66,6 +66,11 @@ public SqliteObjectToStringTranslator(ISqlExpressionFactory sqlExpressionFactory
             return null;
         }
 
+        if (instance.TypeMapping is not null && instance.TypeMapping.ClrType == typeof(string))
+        {
+            return instance;
+        }
+
         if (instance.Type == typeof(bool))
         {
             if (instance is ColumnExpression columnExpression && columnExpression.IsNullable)

test/EFCore.Specification.Tests/Query/GearsOfWarQueryTestBase.cs

@@ -95,6 +95,13 @@ public virtual Task ToString_guid_property_projection(bool async)
                 Assert.Equal(e.B.ToLower(), a.B.ToLower());
             });
 
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual Task ToString_string_property_projection(bool async)
+        => AssertQuery(
+            async,
+            ss => ss.Set<Weapon>().Select(w => w.Name.ToString()));
+
     [ConditionalTheory]
     [MemberData(nameof(IsAsyncData))]
     public virtual Task ToString_boolean_property_non_nullable(bool async)

test/EFCore.SqlServer.FunctionalTests/Query/GearsOfWarQuerySqlServerTest.cs

@@ -4095,6 +4095,15 @@ FROM [Gears] AS [g]
 """);
     }
 
+    public override async Task ToString_string_property_projection(bool async)
+    {
+        await base.ToString_string_property_projection(async);
+
+        AssertSql(@"SELECT [w].[Name]
+FROM [Weapons] AS [w]");
+    }
+
+
     public override async Task ToString_boolean_property_non_nullable(bool async)
     {
         await base.ToString_boolean_property_non_nullable(async);

test/EFCore.SqlServer.FunctionalTests/Query/TPCGearsOfWarQuerySqlServerTest.cs

@@ -12495,6 +12495,14 @@ FROM [Weapons] AS [w]
 """);
     }
 
+    public override async Task ToString_string_property_projection(bool async)
+    {
+        await base.ToString_string_property_projection(async);
+
+        AssertSql(@"SELECT [w].[Name]
+FROM [Weapons] AS [w]");
+    }
+
     public override async Task ToString_boolean_property_non_nullable(bool async)
     {
         await base.ToString_boolean_property_non_nullable(async);

test/EFCore.SqlServer.FunctionalTests/Query/TPTGearsOfWarQuerySqlServerTest.cs

@@ -10734,6 +10734,14 @@ FROM [Weapons] AS [w]
 """);
     }
 
+    public override async Task ToString_string_property_projection(bool async)
+    {
+        await base.ToString_string_property_projection(async);
+
+        AssertSql(@"SELECT [w].[Name]
+FROM [Weapons] AS [w]");
+    }
+
     public override async Task ToString_boolean_property_non_nullable(bool async)
     {
         await base.ToString_boolean_property_non_nullable(async);

test/EFCore.SqlServer.FunctionalTests/Query/TemporalGearsOfWarQuerySqlServerTest.cs

@@ -9004,6 +9004,14 @@ ELSE NULL
 """);
     }
 
+    public override async Task ToString_string_property_projection(bool async)
+    {
+        await base.ToString_string_property_projection(async);
+
+        AssertSql(@"SELECT [w].[Name]
+FROM [Weapons] FOR SYSTEM_TIME AS OF '2010-01-01T00:00:00.0000000' AS [w]");
+    }
+
     public override async Task ToString_boolean_property_non_nullable(bool async)
     {
         await base.ToString_boolean_property_non_nullable(async);

test/EFCore.Sqlite.FunctionalTests/Query/GearsOfWarQuerySqliteTest.cs

@@ -3091,6 +3091,14 @@ SELECT COALESCE(SUM("g"."SquadId"), 0)
 """);
     }
 
+    public override async Task ToString_string_property_projection(bool async)
+    {
+        await base.ToString_string_property_projection(async);
+
+        AssertSql(@"SELECT ""w"".""Name""
+FROM ""Weapons"" AS ""w""");
+    }
+
     public override async Task ToString_boolean_property_non_nullable(bool async)
     {
         await base.ToString_boolean_property_non_nullable(async);