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Query: Add support for custom aggregate operators #28092

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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@ public static readonly IDictionary<Type, ServiceCharacteristics> RelationalServi
{ typeof(IModificationCommandBatchFactory), new ServiceCharacteristics(ServiceLifetime.Scoped) },
{ typeof(IRelationalSqlTranslatingExpressionVisitorFactory), new ServiceCharacteristics(ServiceLifetime.Scoped) },
{ typeof(IMethodCallTranslatorProvider), new ServiceCharacteristics(ServiceLifetime.Scoped) },
{ typeof(IAggregateMethodCallTranslatorProvider), new ServiceCharacteristics(ServiceLifetime.Scoped) },
{ typeof(IMemberTranslatorProvider), new ServiceCharacteristics(ServiceLifetime.Scoped) },
{ typeof(ISqlExpressionFactory), new ServiceCharacteristics(ServiceLifetime.Scoped) },
{ typeof(IRelationalQueryStringFactory), new ServiceCharacteristics(ServiceLifetime.Scoped) },
Expand Down Expand Up @@ -171,6 +172,7 @@ public override EntityFrameworkServicesBuilder TryAddCoreServices()
TryAdd<IShapedQueryCompilingExpressionVisitorFactory, RelationalShapedQueryCompilingExpressionVisitorFactory>();
TryAdd<IQueryableMethodTranslatingExpressionVisitorFactory, RelationalQueryableMethodTranslatingExpressionVisitorFactory>();
TryAdd<IMethodCallTranslatorProvider, RelationalMethodCallTranslatorProvider>();
TryAdd<IAggregateMethodCallTranslatorProvider, RelationalAggregateMethodCallTranslatorProvider>();
TryAdd<IMemberTranslatorProvider, RelationalMemberTranslatorProvider>();
TryAdd<IQueryTranslationPostprocessorFactory, RelationalQueryTranslationPostprocessorFactory>();
TryAdd<IRelationalSqlTranslatingExpressionVisitorFactory, RelationalSqlTranslatingExpressionVisitorFactory>();
Expand Down Expand Up @@ -202,6 +204,7 @@ public override EntityFrameworkServicesBuilder TryAddCoreServices()
.AddDependencyScoped<HistoryRepositoryDependencies>()
.AddDependencyScoped<RelationalCompiledQueryCacheKeyGeneratorDependencies>()
.AddDependencyScoped<RelationalMethodCallTranslatorProviderDependencies>()
.AddDependencyScoped<RelationalAggregateMethodCallTranslatorProviderDependencies>()
.AddDependencyScoped<RelationalMemberTranslatorProviderDependencies>()
.AddDependencyScoped<SqlExpressionFactoryDependencies>()
.AddDependencyScoped<RelationalSqlTranslatingExpressionVisitorDependencies>()
Expand Down
32 changes: 32 additions & 0 deletions src/EFCore.Relational/Query/IAggregateMethodCallTranslator.cs
Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.EntityFrameworkCore.Query.SqlExpressions;

namespace Microsoft.EntityFrameworkCore.Query;

/// <summary>
/// <para>
/// A SQL translator for LINQ <see cref="MethodCallExpression" /> expression represending an aggregate function.
/// </para>
/// <para>
/// This interface is typically used by database providers (and other extensions). It is generally
/// not used in application code.
/// </para>
/// </summary>
public interface IAggregateMethodCallTranslator
{
/// <summary>
/// Translates a LINQ <see cref="MethodCallExpression" /> to a SQL equivalent.
/// </summary>
/// <param name="method">The method info from <see cref="MethodCallExpression.Method" />.</param>
/// <param name="source">The source on which the aggregate method is applied.</param>
/// <param name="arguments">SQL representations of scalar <see cref="MethodCallExpression.Arguments" />.</param>
/// <param name="logger">The query logger to use.</param>
/// <returns>A SQL translation of the <see cref="MethodCallExpression" />.</returns>
SqlExpression? Translate(
MethodInfo method,
EnumerableExpression source,
IReadOnlyList<SqlExpression> arguments,
IDiagnosticsLogger<DbLoggerCategory.Query> logger);
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.EntityFrameworkCore.Query;

/// <summary>
/// Represents plugin for <see cref="IAggregateMethodCallTranslator" />.
/// </summary>
/// <remarks>
/// The service lifetime is <see cref="ServiceLifetime.Scoped" /> and multiple registrations
/// are allowed. This means that each <see cref="DbContext" /> instance will use its own
/// set of instances of this service.
/// The implementations may depend on other services registered with any lifetime.
/// The implementations do not need to be thread-safe.
/// </remarks>
public interface IAggregateMethodCallTranslatorPlugin
{
/// <summary>
/// Gets the method call translators.
/// </summary>
IEnumerable<IAggregateMethodCallTranslator> Translators { get; }
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.EntityFrameworkCore.Query.SqlExpressions;

namespace Microsoft.EntityFrameworkCore.Query;

/// <summary>
/// Provides translations for LINQ <see cref="MethodCallExpression" /> expressions which represents aggregate methods.
/// </summary>
/// <remarks>
/// The service lifetime is <see cref="ServiceLifetime.Scoped" /> and multiple registrations
/// are allowed. This means that each <see cref="DbContext" /> instance will use its own
/// set of instances of this service.
/// The implementations may depend on other services registered with any lifetime.
/// The implementations do not need to be thread-safe.
/// </remarks>
public interface IAggregateMethodCallTranslatorProvider
{
/// <summary>
/// Translates a LINQ aggregate <see cref="MethodCallExpression" /> to a SQL equivalent.
/// </summary>
/// <param name="model">A model to use for translation.</param>
/// <param name="method">The method info from <see cref="MethodCallExpression.Method" />.</param>
/// <param name="source">The source on which the aggregate method is applied.</param>
/// <param name="arguments">SQL representations of scalar <see cref="MethodCallExpression.Arguments" />.</param>
/// <param name="logger">The query logger to use.</param>
/// <returns>A SQL translation of the <see cref="MethodCallExpression" />.</returns>
SqlExpression? Translate(
IModel model,
MethodInfo method,
EnumerableExpression source,
IReadOnlyList<SqlExpression> arguments,
IDiagnosticsLogger<DbLoggerCategory.Query> logger);
}
1 change: 0 additions & 1 deletion src/EFCore.Relational/Query/IMethodCallTranslator.cs
Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics.CodeAnalysis;
using Microsoft.EntityFrameworkCore.Query.SqlExpressions;

namespace Microsoft.EntityFrameworkCore.Query;
Expand Down
10 changes: 6 additions & 4 deletions src/EFCore.Relational/Query/IMethodCallTranslatorProvider.cs
Original file line number Diff line number Diff line change
Expand Up @@ -6,12 +6,14 @@
namespace Microsoft.EntityFrameworkCore.Query;

/// <summary>
/// Provides translations for LINQ <see cref="MethodCallExpression" /> expressions.
/// Provides translations for LINQ <see cref="MethodCallExpression" /> expressions which represents scalar methods.
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/// </summary>
/// <remarks>
/// The service lifetime is <see cref="ServiceLifetime.Singleton" />. This means a single instance
/// is used by many <see cref="DbContext" /> instances. The implementation must be thread-safe.
/// This service cannot depend on services registered as <see cref="ServiceLifetime.Scoped" />.
/// The service lifetime is <see cref="ServiceLifetime.Scoped" /> and multiple registrations
/// are allowed. This means that each <see cref="DbContext" /> instance will use its own
/// set of instances of this service.
/// The implementations may depend on other services registered with any lifetime.
/// The implementations do not need to be thread-safe.
/// </remarks>
public interface IMethodCallTranslatorProvider
{
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,180 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.EntityFrameworkCore.Query.SqlExpressions;

namespace Microsoft.EntityFrameworkCore.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 QueryableAggregateMethodTranslator : IAggregateMethodCallTranslator
{
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 QueryableAggregateMethodTranslator(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 virtual SqlExpression? Translate(
MethodInfo method, EnumerableExpression source, IReadOnlyList<SqlExpression> arguments,
IDiagnosticsLogger<DbLoggerCategory.Query> logger)
{
if (method.DeclaringType == typeof(Queryable))
{
var methodInfo = method.IsGenericMethod
? method.GetGenericMethodDefinition()
: method;
switch (methodInfo.Name)
{
case nameof(Queryable.Average)
when (QueryableMethods.IsAverageWithoutSelector(methodInfo)
|| QueryableMethods.IsAverageWithSelector(methodInfo))
&& source.Selector is SqlExpression averageSqlExpression:
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var averageInputType = averageSqlExpression.Type;
if (averageInputType == typeof(int)
|| averageInputType == typeof(long))
{
averageSqlExpression = _sqlExpressionFactory.ApplyDefaultTypeMapping(
_sqlExpressionFactory.Convert(averageSqlExpression, typeof(double)));
}

averageSqlExpression = CombineTerms(source, averageSqlExpression);
return averageInputType == typeof(float)
? _sqlExpressionFactory.Convert(
_sqlExpressionFactory.Function(
"AVG",
new[] { averageSqlExpression },
nullable: true,
argumentsPropagateNullability: new[] { false },
typeof(double)),
averageSqlExpression.Type,
averageSqlExpression.TypeMapping)
: _sqlExpressionFactory.Function(
"AVG",
new[] { averageSqlExpression },
nullable: true,
argumentsPropagateNullability: new[] { false },
averageSqlExpression.Type,
averageSqlExpression.TypeMapping);

case nameof(Queryable.Count)
when methodInfo == QueryableMethods.CountWithoutPredicate
|| methodInfo == QueryableMethods.CountWithPredicate:
var countSqlExpression = (source.Selector as SqlExpression) ?? _sqlExpressionFactory.Fragment("*");
countSqlExpression = CombineTerms(source, countSqlExpression);
return _sqlExpressionFactory.ApplyDefaultTypeMapping(
_sqlExpressionFactory.Function(
"COUNT",
new[] { countSqlExpression },
nullable: false,
argumentsPropagateNullability: new[] { false },
typeof(int)));

case nameof(Queryable.LongCount)
when methodInfo == QueryableMethods.LongCountWithoutPredicate
|| methodInfo == QueryableMethods.LongCountWithPredicate:
var longCountSqlExpression = (source.Selector as SqlExpression) ?? _sqlExpressionFactory.Fragment("*");
longCountSqlExpression = CombineTerms(source, longCountSqlExpression);

return _sqlExpressionFactory.ApplyDefaultTypeMapping(
_sqlExpressionFactory.Function(
"COUNT",
new[] { longCountSqlExpression },
nullable: false,
argumentsPropagateNullability: new[] { false },
typeof(long)));

case nameof(Queryable.Max)
when (methodInfo == QueryableMethods.MaxWithoutSelector
|| methodInfo == QueryableMethods.MaxWithSelector)
&& source.Selector is SqlExpression maxSqlExpression:
maxSqlExpression = CombineTerms(source, maxSqlExpression);
return _sqlExpressionFactory.Function(
"MAX",
new[] { maxSqlExpression },
nullable: true,
argumentsPropagateNullability: new[] { false },
maxSqlExpression.Type,
maxSqlExpression.TypeMapping);

case nameof(Queryable.Min)
when (methodInfo == QueryableMethods.MinWithoutSelector
|| methodInfo == QueryableMethods.MinWithSelector)
&& source.Selector is SqlExpression minSqlExpression:
minSqlExpression = CombineTerms(source, minSqlExpression);
return _sqlExpressionFactory.Function(
"MIN",
new[] { minSqlExpression },
nullable: true,
argumentsPropagateNullability: new[] { false },
minSqlExpression.Type,
minSqlExpression.TypeMapping);

case nameof(Queryable.Sum)
when (QueryableMethods.IsSumWithoutSelector(methodInfo)
|| QueryableMethods.IsSumWithSelector(methodInfo))
&& source.Selector is SqlExpression sumSqlExpression:
sumSqlExpression = CombineTerms(source, sumSqlExpression);
var sumInputType = sumSqlExpression.Type;
return sumInputType == typeof(float)
? _sqlExpressionFactory.Convert(
_sqlExpressionFactory.Function(
"SUM",
new[] { sumSqlExpression },
nullable: true,
argumentsPropagateNullability: new[] { false },
typeof(double)),
sumInputType,
sumSqlExpression.TypeMapping)
: _sqlExpressionFactory.Function(
"SUM",
new[] { sumSqlExpression },
nullable: true,
argumentsPropagateNullability: new[] { false },
sumInputType,
sumSqlExpression.TypeMapping);
}
}

return null;
}

private SqlExpression CombineTerms(EnumerableExpression enumerableExpression, SqlExpression sqlExpression)
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{
if (enumerableExpression.Predicate != null)
{
if (sqlExpression is SqlFragmentExpression)
{
sqlExpression = _sqlExpressionFactory.Constant(1);
}

sqlExpression = _sqlExpressionFactory.Case(
new List<CaseWhenClause> { new(enumerableExpression.Predicate, sqlExpression) },
elseResult: null);
}

if (enumerableExpression.IsDistinct)
{
sqlExpression = new DistinctExpression(sqlExpression);
}

return sqlExpression;
}
}
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