Query: add translation for string.IndexOf(string, int) #25396

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

@@ -24,6 +24,9 @@ public class SqlServerStringMethodTranslator : IMethodCallTranslator
         private static readonly MethodInfo _indexOfMethodInfo
             = typeof(string).GetRequiredRuntimeMethod(nameof(string.IndexOf), new[] { typeof(string) });
 
+        private static readonly MethodInfo _indexOfMethodInfoWithStartingPosition
+            = typeof(string).GetRequiredRuntimeMethod(nameof(string.IndexOf), new[] { typeof(string), typeof(int) });
+
         private static readonly MethodInfo _replaceMethodInfo
             = typeof(string).GetRequiredRuntimeMethod(nameof(string.Replace), new[] { typeof(string), typeof(string) });
 
@@ -120,46 +123,12 @@ public SqlServerStringMethodTranslator(ISqlExpressionFactory sqlExpressionFactor
             {
                 if (_indexOfMethodInfo.Equals(method))
                 {
-                    var argument = arguments[0];
-                    var stringTypeMapping = ExpressionExtensions.InferTypeMapping(instance, argument)!;
-                    argument = _sqlExpressionFactory.ApplyTypeMapping(argument, stringTypeMapping);
-
-                    SqlExpression charIndexExpression;
-                    var storeType = stringTypeMapping.StoreType;
-                    if (string.Equals(storeType, "nvarchar(max)", StringComparison.OrdinalIgnoreCase)
-                        || string.Equals(storeType, "varchar(max)", StringComparison.OrdinalIgnoreCase))
-                    {
-                        charIndexExpression = _sqlExpressionFactory.Function(
-                            "CHARINDEX",
-                            new[] { argument, _sqlExpressionFactory.ApplyTypeMapping(instance, stringTypeMapping) },
-                            nullable: true,
-                            argumentsPropagateNullability: new[] { true, true },
-                            typeof(long));
-
-                        charIndexExpression = _sqlExpressionFactory.Convert(charIndexExpression, typeof(int));
-                    }
-                    else
-                    {
-                        charIndexExpression = _sqlExpressionFactory.Function(
-                            "CHARINDEX",
-                            new[] { argument, _sqlExpressionFactory.ApplyTypeMapping(instance, stringTypeMapping) },
-                            nullable: true,
-                            argumentsPropagateNullability: new[] { true, true },
-                            method.ReturnType);
-                    }
-
-                    charIndexExpression = _sqlExpressionFactory.Subtract(charIndexExpression, _sqlExpressionFactory.Constant(1));
+                    return TranslateIndexOf(instance, method, arguments[0], null);
+                }
 
-                    return _sqlExpressionFactory.Case(
-                        new[]
-                        {
-                            new CaseWhenClause(
-                                _sqlExpressionFactory.Equal(
-                                    argument,
-                                    _sqlExpressionFactory.Constant(string.Empty, stringTypeMapping)),
-                                _sqlExpressionFactory.Constant(0))
-                        },
-                        charIndexExpression);
+                if (_indexOfMethodInfoWithStartingPosition.Equals(method))
+                {
+                    return TranslateIndexOf(instance, method, arguments[0], arguments[1]);
                 }
 
                 if (_replaceMethodInfo.Equals(method))
@@ -470,6 +439,61 @@ private SqlExpression TranslateStartsEndsWith(SqlExpression instance, SqlExpress
                 pattern);
         }
 
+        private SqlExpression TranslateIndexOf(SqlExpression instance, MethodInfo method, SqlExpression searchExpression, SqlExpression? startIndex)
+        {
+            var stringTypeMapping = ExpressionExtensions.InferTypeMapping(instance, searchExpression)!;
+            searchExpression = _sqlExpressionFactory.ApplyTypeMapping(searchExpression, stringTypeMapping);
+
+            SqlExpression[] charIndexArguments;
+            if (startIndex is null)
+            {
+                charIndexArguments = new[] { searchExpression, _sqlExpressionFactory.ApplyTypeMapping(instance, stringTypeMapping) };
+            }
+            else
+            {
+                var startIndexSql = _sqlExpressionFactory.Add(startIndex, _sqlExpressionFactory.Constant(1));
+                charIndexArguments = new[] { searchExpression, _sqlExpressionFactory.ApplyTypeMapping(instance, stringTypeMapping), startIndexSql };
+            }
+
+            SqlExpression charIndexExpression;
+            var storeType = stringTypeMapping.StoreType;
+            if (string.Equals(storeType, "nvarchar(max)", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(storeType, "varchar(max)", StringComparison.OrdinalIgnoreCase))
+            {
+                charIndexExpression = _sqlExpressionFactory.Function(
+                    "CHARINDEX",
+                    charIndexArguments,
+                    nullable: true,
+                    argumentsPropagateNullability: new[] { true, true },
+                    typeof(long));
+
+                charIndexExpression = _sqlExpressionFactory.Convert(charIndexExpression, typeof(int));
+            }
+            else
+            {
+                charIndexExpression = _sqlExpressionFactory.Function(
+                    "CHARINDEX",
+                    charIndexArguments,
+                    nullable: true,
+                    argumentsPropagateNullability: new[] { true, true },
+                    method.ReturnType);
+            }
+
+            charIndexExpression = _sqlExpressionFactory.Subtract(charIndexExpression, _sqlExpressionFactory.Constant(1));
+
+            return _sqlExpressionFactory.Case(
+                new[]
+                {
+                            new CaseWhenClause(
+                                _sqlExpressionFactory.Equal(
+                                    searchExpression,
+                                    _sqlExpressionFactory.Constant(string.Empty, stringTypeMapping)),
+                                _sqlExpressionFactory.Constant(0))
+                },
+                charIndexExpression);
+        }
+
+
         // See https://docs.microsoft.com/en-us/sql/t-sql/language-elements/like-transact-sql
         private bool IsLikeWildChar(char c)
             => c == '%' || c == '_' || c == '[';

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

@@ -1528,6 +1528,15 @@ public virtual Task Indexof_with_emptystring(bool async)
                 ss => ss.Set<Customer>().Where(c => c.CustomerID == "ALFKI").Select(c => c.ContactName.IndexOf(string.Empty)));
         }
 
+        [ConditionalTheory]
+        [MemberData(nameof(IsAsyncData))]
+        public virtual Task Indexof_with_one_arg(bool async)
+        {
+            return AssertQueryScalar(
+                async,
+                ss => ss.Set<Customer>().Where(c => c.CustomerID == "ALFKI").Select(c => c.ContactName.IndexOf("a")));
+        }
+
         [ConditionalTheory]
         [MemberData(nameof(IsAsyncData))]
         public virtual Task Indexof_with_starting_position(bool async)

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

@@ -1498,13 +1498,28 @@ FROM [Customers] AS [c]
 WHERE [c].[CustomerID] = N'ALFKI'");
         }
 
-        [ConditionalTheory(Skip = "issue #25396")]
+        public override async Task Indexof_with_one_arg(bool async)
+        {
+            await base.Indexof_with_one_arg(async);
+
+            AssertSql(
+                @"SELECT CASE
+    WHEN N'a' = N'' THEN 0
+    ELSE CAST(CHARINDEX(N'a', [c].[ContactName]) AS int) - 1
+END
+FROM [Customers] AS [c]
+WHERE [c].[CustomerID] = N'ALFKI'");
+        }
+
         public override async Task Indexof_with_starting_position(bool async)
         {
             await base.Indexof_with_starting_position(async);
 
             AssertSql(
-                @"SELECT [c].[ContactName]
+                @"SELECT CASE
+    WHEN N'a' = N'' THEN 0
+    ELSE CAST(CHARINDEX(N'a', [c].[ContactName], 3 + 1) AS int) - 1
+END
 FROM [Customers] AS [c]
 WHERE [c].[CustomerID] = N'ALFKI'");
         }