From dc559cf2d8b7bbe2f7b5e58411fda4aae5cb0e4b Mon Sep 17 00:00:00 2001
From: Rafael Almeida <ralms@ralms.net>
Date: Fri, 3 Jan 2020 15:15:51 -0300
Subject: [PATCH] Sqlite: Support translation of ToString * Resolve: #17223

---
 .../SqliteMethodCallTranslatorProvider.cs     |  3 +-
 .../SqliteObjectToStringTranslator.cs         | 55 +++++++++++++++++++
 .../NorthwindMiscellaneousQuerySqliteTest.cs  | 41 +++++++++++++-
 3 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100644 src/EFCore.Sqlite.Core/Query/Internal/SqliteObjectToStringTranslator.cs

diff --git a/src/EFCore.Sqlite.Core/Query/Internal/SqliteMethodCallTranslatorProvider.cs b/src/EFCore.Sqlite.Core/Query/Internal/SqliteMethodCallTranslatorProvider.cs
index f3c8d14fd9d..2aa849f0e39 100644
--- a/src/EFCore.Sqlite.Core/Query/Internal/SqliteMethodCallTranslatorProvider.cs
+++ b/src/EFCore.Sqlite.Core/Query/Internal/SqliteMethodCallTranslatorProvider.cs
@@ -19,7 +19,8 @@ public SqliteMethodCallTranslatorProvider([NotNull] RelationalMethodCallTranslat
                     new SqliteByteArrayMethodTranslator(sqlExpressionFactory),
                     new SqliteDateTimeAddTranslator(sqlExpressionFactory),
                     new SqliteMathTranslator(sqlExpressionFactory),
-                    new SqliteStringMethodTranslator(sqlExpressionFactory)
+                    new SqliteObjectToStringTranslator(sqlExpressionFactory),
+                    new SqliteStringMethodTranslator(sqlExpressionFactory),
                 });
         }
     }
diff --git a/src/EFCore.Sqlite.Core/Query/Internal/SqliteObjectToStringTranslator.cs b/src/EFCore.Sqlite.Core/Query/Internal/SqliteObjectToStringTranslator.cs
new file mode 100644
index 00000000000..792d30c269b
--- /dev/null
+++ b/src/EFCore.Sqlite.Core/Query/Internal/SqliteObjectToStringTranslator.cs
@@ -0,0 +1,55 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+using JetBrains.Annotations;
+using Microsoft.EntityFrameworkCore.Query;
+using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
+using Microsoft.EntityFrameworkCore.Utilities;
+
+namespace Microsoft.EntityFrameworkCore.Sqlite.Query.Internal
+{
+    public class SqliteObjectToStringTranslator : IMethodCallTranslator
+    {
+        private static readonly HashSet<Type> _typeMapping = new HashSet<Type>
+            {
+                typeof(int),
+                typeof(long),
+                typeof(DateTime),
+                typeof(Guid),
+                typeof(byte),
+                typeof(byte[]),
+                typeof(double),
+                typeof(DateTimeOffset),
+                typeof(char),
+                typeof(short),
+                typeof(float),
+                typeof(decimal),
+                typeof(TimeSpan),
+                typeof(uint),
+                typeof(ushort),
+                typeof(ulong),
+                typeof(sbyte),
+            };
+
+        private readonly ISqlExpressionFactory _sqlExpressionFactory;
+
+        public SqliteObjectToStringTranslator([NotNull] ISqlExpressionFactory sqlExpressionFactory)
+            => _sqlExpressionFactory = sqlExpressionFactory;
+
+        public virtual SqlExpression Translate(SqlExpression instance, MethodInfo method, IReadOnlyList<SqlExpression> arguments)
+        {
+            Check.NotNull(method, nameof(method));
+            Check.NotNull(arguments, nameof(arguments));
+
+            return method.Name == nameof(ToString)
+                && arguments.Count == 0
+                && instance != null
+                && _typeMapping.Contains(instance.Type.UnwrapNullableType())
+                    ? _sqlExpressionFactory.Convert(instance, typeof(string))
+                    : null;
+        }
+    }
+}
diff --git a/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindMiscellaneousQuerySqliteTest.cs b/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindMiscellaneousQuerySqliteTest.cs
index dd2fd6d83bf..80df794c021 100644
--- a/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindMiscellaneousQuerySqliteTest.cs
+++ b/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindMiscellaneousQuerySqliteTest.cs
@@ -21,8 +21,15 @@ public NorthwindMiscellaneousQuerySqliteTest(NorthwindQuerySqliteFixture<NoopMod
             //Fixture.TestSqlLoggerFactory.SetTestOutputHelper(testOutputHelper);
         }
 
-        public override Task Query_expression_with_to_string_and_contains(bool async)
-            => AssertTranslationFailed(() => base.Query_expression_with_to_string_and_contains(async));
+        public override async Task Query_expression_with_to_string_and_contains(bool async)
+        {
+            await base.Query_expression_with_to_string_and_contains(async);
+
+            AssertSql(
+                @"SELECT ""o"".""CustomerID""
+FROM ""Orders"" AS ""o""
+WHERE ""o"".""OrderDate"" IS NOT NULL AND (('10' = '') OR (instr(CAST(""o"".""EmployeeID"" AS TEXT), '10') > 0))");
+        }
 
         public override async Task Take_Skip(bool async)
         {
@@ -236,6 +243,36 @@ LIMIT @__p_0
 ) AS ""t""");
         }
 
+        public override async Task Select_expression_other_to_string(bool async)
+        {
+            await base.Select_expression_other_to_string(async);
+
+            AssertSql(
+                @"SELECT CAST(""o"".""OrderDate"" AS TEXT) AS ""ShipName""
+FROM ""Orders"" AS ""o""
+WHERE ""o"".""OrderDate"" IS NOT NULL");
+        }
+
+        public override async Task Select_expression_long_to_string(bool async)
+        {
+            await base.Select_expression_long_to_string(async);
+
+            AssertSql(
+                @"SELECT CAST(CAST(""o"".""OrderID"" AS INTEGER) AS TEXT) AS ""ShipName""
+FROM ""Orders"" AS ""o""
+WHERE ""o"".""OrderDate"" IS NOT NULL");
+        }
+
+        public override async Task Select_expression_int_to_string(bool async)
+        {
+            await base.Select_expression_int_to_string(async);
+
+            AssertSql(
+                @"SELECT CAST(""o"".""OrderID"" AS TEXT) AS ""ShipName""
+FROM ""Orders"" AS ""o""
+WHERE ""o"".""OrderDate"" IS NOT NULL");
+        }
+
         public override Task Complex_nested_query_doesnt_try_binding_to_grandparent_when_parent_returns_complex_result(bool async)
             => null;