Ticket #4 : Allow filtering

Author: habarthierry-hue

samples/EFCore.Cassandra.Samples/Program.cs

@@ -28,11 +28,16 @@ static void Main(string[] args)
                 Console.WriteLine($"Number of applicants '{dbContext.Applicants.LongCount()}'");
 
                 Console.WriteLine("Get applicants by partition key");
-                var filteredApplicants = dbContext.Applicants.Where(_ => _.Id == ApplicantPartitionId).ToList();
+                var filteredApplicants = dbContext.Applicants.Where(_ => _.Id == ApplicantPartitionId, false).ToList();
                 Console.WriteLine($"Number of applicants '{filteredApplicants.Count}'");
 
+                Console.WriteLine("Get applicants (ALLOW FILTERING)");
+                var allowedFilteredApplicants = dbContext.Applicants.Where(_ => _.LastName == "lastname", true).ToList();
+                Console.WriteLine($"Number of applicants {allowedFilteredApplicants.Count}");
+
                 Console.WriteLine("Order applicants by 'order'");
-                var orderedApplicants = dbContext.Applicants.Where(_ => _.Id == ApplicantPartitionId).OrderBy(_ => _.Order).ToList();
+                var orderedApplicants = dbContext.Applicants.Where(_ => _.Id == ApplicantPartitionId)
+                    .OrderBy(_ => _.Order).ToList();
                 Console.WriteLine($"Number of applicants {orderedApplicants.Count}");
 
                 Console.WriteLine("Update the applicant");

src/EFCore.Cassandra/CassandraServiceCollectionExtensions.cs

@@ -5,6 +5,7 @@
 using Microsoft.EntityFrameworkCore.Cassandra.Infrastructure.Internal;
 using Microsoft.EntityFrameworkCore.Cassandra.Migrations;
 using Microsoft.EntityFrameworkCore.Cassandra.Migrations.Internal;
+using Microsoft.EntityFrameworkCore.Cassandra.Query.Internal;
 using Microsoft.EntityFrameworkCore.Cassandra.Query.Sql.Internal;
 using Microsoft.EntityFrameworkCore.Cassandra.Storage;
 using Microsoft.EntityFrameworkCore.Cassandra.Storage.Internal;
@@ -43,6 +44,7 @@ public static IServiceCollection AddEntityFrameworkCassandra(this IServiceCollec
                 .TryAdd<IRelationalSqlTranslatingExpressionVisitorFactory, CassandraSqlTranslatingExpressionVisitorFactory>()
                 .TryAdd<IQuerySqlGeneratorFactory, CassandraSqlGeneratorFactory>()
                 .TryAdd<IUpdateSqlGenerator, CassandraUpdateSqlGenerator>()
+                .TryAdd<IQueryableMethodTranslatingExpressionVisitorFactory, CassandraQueryableMethodTranslatingExpressionVisitorFactory>()
                 .TryAddProviderSpecificServices(b => b.TryAddScoped<ICassandraRelationalConnection, CassandraRelationalConnection>())
                 .TryAddProviderSpecificServices(b => b.TryAddTransient<ICassandraHistoryRepository, CassandraHistoryRepository>());
 

src/EFCore.Cassandra/Extensions/CassandraQueryable.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
+using System.Text;
+
+namespace System.Linq
+{
+    public static class CassandraQueryable
+    {
+        public static IQueryable<TSource> Where<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, bool>> predicate, bool allowFiltering = false)
+        {
+            if (source == null)
+            {
+                throw new ArgumentNullException(nameof(source));
+            }
+            if (predicate == null)
+            {
+                throw new ArgumentNullException(nameof(predicate));
+            }
+
+            if (allowFiltering)
+            {
+                return source.Provider.CreateQuery<TSource>(
+                   Expression.Call(
+                       null,
+                       Casandra_Where_TSource_2(typeof(TSource)),
+                       source.Expression, Expression.Quote(predicate), Expression.Constant(allowFiltering)
+                       ));
+
+            }
+
+            return source.Provider.CreateQuery<TSource>(
+                   Expression.Call(
+                       null,
+                       Where_TSource_2(typeof(TSource)),
+                       source.Expression, Expression.Quote(predicate)
+                       ));
+        }
+
+        private static MethodInfo? s_Cassandra_Where_TSource_2;
+        private static MethodInfo? s_Where_TSource_2;
+
+        private static MethodInfo Casandra_Where_TSource_2(Type TSource) =>
+             (s_Cassandra_Where_TSource_2 ??
+             (s_Cassandra_Where_TSource_2 = new Func<IQueryable<object>, Expression<Func<object, bool>>, bool, IQueryable<object>>(CassandraQueryable.Where).GetMethodInfo().GetGenericMethodDefinition()))
+              .MakeGenericMethod(TSource);
+
+        private static MethodInfo Where_TSource_2(Type TSource) =>
+             (s_Where_TSource_2 ??
+             (s_Where_TSource_2 = new Func<IQueryable<object>, Expression<Func<object, bool>>, IQueryable<object>>(Queryable.Where).GetMethodInfo().GetGenericMethodDefinition()))
+              .MakeGenericMethod(TSource);
+    }
+}

src/EFCore.Cassandra/Query/CassandraQuerySqlGenerator.cs

@@ -1,5 +1,6 @@
 // Copyright (c) SimpleIdServer. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+using Microsoft.EntityFrameworkCore.Cassandra.Query.Internal;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
 using Microsoft.EntityFrameworkCore.Storage;
@@ -64,6 +65,11 @@ private bool IsNonComposedSetOperation(SelectExpression selectExpression)
                                 column.Name, setOperation.Source1.Projection[index].Alias, StringComparison.OrdinalIgnoreCase))
                     .All(e => e);
 
+        public override Expression Visit(Expression node)
+        {
+            return base.Visit(node);
+        }
+
         protected override Expression VisitSelect(SelectExpression selectExpression)
         {
             if (IsNonComposedSetOperation(selectExpression))
@@ -109,8 +115,16 @@ protected override Expression VisitSelect(SelectExpression selectExpression)
             if (selectExpression.Predicate != null)
             {
                 Sql.AppendLine().Append("WHERE ");
-
-                Visit(selectExpression.Predicate);
+                var cassandraBinaryExpression = selectExpression.Predicate as CassandraAllowFilteringBinaryExpression;
+                if (cassandraBinaryExpression != null)
+                {
+                    Visit(cassandraBinaryExpression.BinaryExpression);
+                    Sql.AppendLine(" ALLOW FILTERING");
+                }
+                else
+                {
+                    Visit(selectExpression.Predicate);
+                }
             }
 
             if (selectExpression.GroupBy.Count > 0)

src/EFCore.Cassandra/Query/Sql/Internal/CassandraAllowFilteringBinaryExpression.cs

@@ -0,0 +1,35 @@
+// Copyright (c) SimpleIdServer. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+using Microsoft.EntityFrameworkCore.Query;
+using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
+using Microsoft.EntityFrameworkCore.Storage;
+using System;
+using System.Linq.Expressions;
+
+namespace Microsoft.EntityFrameworkCore.Cassandra.Query.Internal
+{
+    public class CassandraAllowFilteringBinaryExpression : SqlExpression
+    {
+        public CassandraAllowFilteringBinaryExpression(
+            RelationalTypeMapping typeMapping,
+            Type type,
+            SqlExpression binaryExpression)
+            : base(type, typeMapping)
+        {
+            BinaryExpression = binaryExpression;
+        }
+
+        public SqlExpression BinaryExpression { get; set; }
+
+        public override void Print(ExpressionPrinter expressionPrinter)
+        {
+
+        }
+
+        protected override Expression VisitChildren(ExpressionVisitor visitor)
+        {
+            return this;
+        }
+    }
+}