implements #18845

src/EFCore.Sqlite.Core/Infrastructure/Internal/SqliteOptionsExtension.cs

@@ -19,6 +19,7 @@ public class SqliteOptionsExtension : RelationalOptionsExtension
     {
         private DbContextOptionsExtensionInfo _info;
         private bool _loadSpatialite;
+        private bool _enableRegex;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -42,6 +43,7 @@ protected SqliteOptionsExtension([NotNull] SqliteOptionsExtension copyFrom)
             : base(copyFrom)
         {
             _loadSpatialite = copyFrom._loadSpatialite;
+            _enableRegex = copyFrom._enableRegex;
         }
 
         /// <summary>
@@ -86,6 +88,29 @@ public virtual SqliteOptionsExtension WithLoadSpatialite(bool loadSpatialite)
             return clone;
         }
 
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public virtual bool EnableRegex => _enableRegex;
+
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public virtual SqliteOptionsExtension WithEnableRegex()
+        {
+            var clone = (SqliteOptionsExtension)Clone();
+
+            clone._enableRegex = true;
+
+            return clone;
+        }
+
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
         ///     the same compatibility standards as public APIs. It may be changed or removed without notice in

src/EFCore.Sqlite.Core/Infrastructure/SqliteDbContextOptionsBuilder.cs

@@ -27,5 +27,13 @@ public SqliteDbContextOptionsBuilder([NotNull] DbContextOptionsBuilder optionsBu
             : base(optionsBuilder)
         {
         }
+
+        /// <summary>
+        ///     Configures enabling Regex.IsMatch method translation
+        /// </summary>
+        public virtual SqliteDbContextOptionsBuilder EnableRegex()
+        {
+            return WithOption(e => e.WithEnableRegex());
+        }
     }
 }

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

@@ -31,7 +31,8 @@ public SqliteMethodCallTranslatorProvider([NotNull] RelationalMethodCallTranslat
                     new SqliteByteArrayMethodTranslator(sqlExpressionFactory),
                     new SqliteDateTimeAddTranslator(sqlExpressionFactory),
                     new SqliteMathTranslator(sqlExpressionFactory),
-                    new SqliteStringMethodTranslator(sqlExpressionFactory)
+                    new SqliteStringMethodTranslator(sqlExpressionFactory),
+                    new SqliteRegexTranslator(sqlExpressionFactory)
                 });
         }
     }

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

@@ -0,0 +1,66 @@
+// 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.Diagnostics.CodeAnalysis;
+using System.Reflection;
+using System.Text.RegularExpressions;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.EntityFrameworkCore.Query;
+using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
+using Microsoft.EntityFrameworkCore.Utilities;
+
+namespace Microsoft.EntityFrameworkCore.Sqlite.Query.Internal
+{
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public class SqliteRegexTranslator : IMethodCallTranslator
+    {
+        private readonly ISqlExpressionFactory _sqlExpressionFactory;
+
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public SqliteRegexTranslator([NotNull] ISqlExpressionFactory sqlExpressionFactory)
+        {
+            _sqlExpressionFactory = sqlExpressionFactory;
+        }
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public SqlExpression Translate(SqlExpression instance,
+            MethodInfo method,
+            IReadOnlyList<SqlExpression> arguments,
+            IDiagnosticsLogger<DbLoggerCategory.Query> logger)
+        {
+            Check.NotNull(method, nameof(method));
+            Check.NotNull(arguments, nameof(arguments));
+            Check.NotNull(logger, nameof(logger));
+
+            var regexIsMatchMethod = typeof(Regex).GetMethod(nameof(Regex.IsMatch), new Type[] { typeof(string), typeof(string) });
+
+            if (method == regexIsMatchMethod)
+            {
+                return _sqlExpressionFactory.Function("regexp",
+                    arguments,
+                    false,
+                    new[] { false, false },
+                    typeof(bool),
+                    arguments[0].TypeMapping);
+            }
+
+            return null;
+        }
+    }
+}

src/EFCore.Sqlite.Core/Storage/Internal/SqliteRelationalConnection.cs

@@ -5,6 +5,7 @@
 using System.Data.Common;
 using System.Globalization;
 using System.Linq;
+using System.Text.RegularExpressions;
 using JetBrains.Annotations;
 using Microsoft.Data.Sqlite;
 using Microsoft.EntityFrameworkCore.Diagnostics;
@@ -37,6 +38,7 @@ public class SqliteRelationalConnection : RelationalConnection, ISqliteRelationa
         private readonly IDiagnosticsLogger<DbLoggerCategory.Infrastructure> _logger;
         private readonly bool _loadSpatialite;
         private readonly int? _commandTimeout;
+        private readonly bool _enableRegex;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -59,6 +61,7 @@ public SqliteRelationalConnection(
             if (optionsExtension != null)
             {
                 _loadSpatialite = optionsExtension.LoadSpatialite;
+                _enableRegex = optionsExtension.EnableRegex;
 
                 var relationalOptions = RelationalOptionsExtension.Extract(dependencies.ContextOptions);
                 _commandTimeout = relationalOptions.CommandTimeout;
@@ -114,6 +117,21 @@ private void InitializeDbConnection(DbConnection connection)
                     sqliteConnection.DefaultTimeout = _commandTimeout.Value;
                 }
 
+                if (_enableRegex)
+                {
+                    sqliteConnection.CreateFunction<string, string, bool>(
+                        "regexp",
+                        (pattern, input) =>
+                        {
+                            if (input == null || pattern == null)
+                            {
+                                return false;
+                            }
+
+                            return Regex.IsMatch(pattern, input);
+                        });
+                }
+
                 sqliteConnection.CreateFunction<object, object, object>(
                     "ef_mod",
                     (dividend, divisor) =>

test/EFCore.Sqlite.FunctionalTests/RegexIsMatchTest.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Linq;
+using System.Text.RegularExpressions;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.TestUtilities;
+using Xunit;
+
+namespace Microsoft.EntityFrameworkCore
+{
+    public class RegexIsMatchTest : IClassFixture<RegexIsMatchFixture>
+    {
+        public RegexIsMatchTest(RegexIsMatchFixture fixture)
+            => Fixture = fixture;
+        protected RegexIsMatchFixture Fixture { get; }
+
+        [ConditionalFact]
+        public void Can_use_Regex_IsMatch()
+        {
+            using (var context = CreateContext())
+            {
+                var honeyDijon = context.Add(new User { Name = "Test1" }).Entity;
+                var buffaloBleu = context.Add(new User { Name = "NTest2" }).Entity;
+                var buffaloBleuNull = context.Add(new User { Name = null }).Entity;
+
+                context.SaveChanges();
+
+                var startingWithT = context.Users.Where(f => Regex.IsMatch(f.Name, @"^T"));
+
+                var nullPattern = context.Users.Where(f => Regex.IsMatch(f.Name, null));
+
+                Assert.Single(startingWithT);
+                Assert.Empty(nullPattern);
+            }
+        }
+
+        private RegexIsMatchContext CreateContext()
+            => Fixture.CreateContext();
+    }
+    public class RegexIsMatchFixture : SharedStoreFixtureBase<RegexIsMatchContext>
+    {
+        protected override string StoreName { get; } = "RegexIsMatchTest";
+
+        protected override ITestStoreFactory TestStoreFactory
+            => SqliteTestStoreFactory.Instance;
+
+        protected override Type ContextType
+            => typeof(RegexIsMatchContext);
+
+        public override DbContextOptionsBuilder AddOptions(DbContextOptionsBuilder builder)
+        {
+            return base.AddOptions(builder).UseSqlite(f => f.EnableRegex());
+        }
+    }
+
+    public class RegexIsMatchContext : PoolableDbContext
+    {
+        public RegexIsMatchContext(DbContextOptions options)
+            : base(options)
+        {
+        }
+
+        public DbSet<User> Users { get; set; }
+    }
+
+    public class User
+    {
+        public int Id { get; set; }
+        public string Name { get; set; }
+    }
+}

test/EFCore.Sqlite.Tests/SqliteDbContextOptionsBuilderExtensionsTest.cs

@@ -96,5 +96,16 @@ public void Can_add_extension_with_connection_using_generic_options()
             Assert.Same(connection, extension.Connection);
             Assert.Null(extension.ConnectionString);
         }
+
+        [ConditionalFact]
+        public void Can_add_extension_with_enable_regex()
+        {
+            var optionsBuilder = new DbContextOptionsBuilder();
+            optionsBuilder.UseSqlite("Database=Crunchie", b => b.EnableRegex()) ;
+
+            var extension = optionsBuilder.Options.Extensions.OfType<SqliteOptionsExtension>().Single();
+
+            Assert.True(extension.EnableRegex);
+        }
     }
 }