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QueryableExtensions.cs
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QueryableExtensions.cs
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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
namespace System.Data.Entity
{
using System.Collections;
using System.Collections.Generic;
using System.Data.Entity.Core.Objects;
using System.Data.Entity.Infrastructure;
using System.Data.Entity.Internal;
using System.Data.Entity.Internal.Linq;
using System.Data.Entity.Resources;
using System.Data.Entity.Utilities;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;
/// <summary>
/// Useful extension methods for use with Entity Framework LINQ queries.
/// </summary>
public static class QueryableExtensions
{
#region Private static fields
#if !NET40
private static readonly MethodInfo _first = GetMethod(
"First", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _first_Predicate = GetMethod(
"First", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _firstOrDefault = GetMethod(
"FirstOrDefault", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _firstOrDefault_Predicate = GetMethod(
"FirstOrDefault", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _single = GetMethod(
"Single", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _single_Predicate = GetMethod(
"Single", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _singleOrDefault = GetMethod(
"SingleOrDefault", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _singleOrDefault_Predicate = GetMethod(
"SingleOrDefault", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _contains = GetMethod(
"Contains", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
T
});
private static readonly MethodInfo _any = GetMethod(
"Any", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _any_Predicate = GetMethod(
"Any", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _all_Predicate = GetMethod(
"All", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _count = GetMethod(
"Count", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _count_Predicate = GetMethod(
"Count", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _longCount = GetMethod(
"LongCount", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _longCount_Predicate = GetMethod(
"LongCount", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(bool)))
});
private static readonly MethodInfo _min = GetMethod(
"Min", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _min_Selector = GetMethod(
"Min", (T, U) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, U))
});
private static readonly MethodInfo _max = GetMethod(
"Max", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T)
});
private static readonly MethodInfo _max_Selector = GetMethod(
"Max", (T, U) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, U))
});
private static readonly MethodInfo _sum_Int = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<int>)
});
private static readonly MethodInfo _sum_IntNullable = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<int?>)
});
private static readonly MethodInfo _sum_Long = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<long>)
});
private static readonly MethodInfo _sum_LongNullable = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<long?>)
});
private static readonly MethodInfo _sum_Float = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<float>)
});
private static readonly MethodInfo _sum_FloatNullable = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<float?>)
});
private static readonly MethodInfo _sum_Double = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<double>)
});
private static readonly MethodInfo _sum_DoubleNullable = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<double?>)
});
private static readonly MethodInfo _sum_Decimal = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<decimal>)
});
private static readonly MethodInfo _sum_DecimalNullable = GetMethod(
"Sum", () => new[]
{
typeof(IQueryable<decimal?>)
});
private static readonly MethodInfo _sum_Int_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(int)))
});
private static readonly MethodInfo _sum_IntNullable_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(int?)))
});
private static readonly MethodInfo _sum_Long_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(long)))
});
private static readonly MethodInfo _sum_LongNullable_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(long?)))
});
private static readonly MethodInfo _sum_Float_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(float)))
});
private static readonly MethodInfo _sum_FloatNullable_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(float?)))
});
private static readonly MethodInfo _sum_Double_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(double)))
});
private static readonly MethodInfo _sum_DoubleNullable_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(double?)))
});
private static readonly MethodInfo _sum_Decimal_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(decimal)))
});
private static readonly MethodInfo _sum_DecimalNullable_Selector = GetMethod(
"Sum", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(decimal?)))
});
private static readonly MethodInfo _average_Int = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<int>)
});
private static readonly MethodInfo _average_IntNullable = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<int?>)
});
private static readonly MethodInfo _average_Long = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<long>)
});
private static readonly MethodInfo _average_LongNullable = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<long?>)
});
private static readonly MethodInfo _average_Float = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<float>)
});
private static readonly MethodInfo _average_FloatNullable = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<float?>)
});
private static readonly MethodInfo _average_Double = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<double>)
});
private static readonly MethodInfo _average_DoubleNullable = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<double?>)
});
private static readonly MethodInfo _average_Decimal = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<decimal>)
});
private static readonly MethodInfo _average_DecimalNullable = GetMethod(
"Average", () => new[]
{
typeof(IQueryable<decimal?>)
});
private static readonly MethodInfo _average_Int_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(int)))
});
private static readonly MethodInfo _average_IntNullable_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(int?)))
});
private static readonly MethodInfo _average_Long_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(long)))
});
private static readonly MethodInfo _average_LongNullable_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(long?)))
});
private static readonly MethodInfo _average_Float_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(float)))
});
private static readonly MethodInfo _average_FloatNullable_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(float?)))
});
private static readonly MethodInfo _average_Double_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(double)))
});
private static readonly MethodInfo _average_DoubleNullable_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(double?)))
});
private static readonly MethodInfo _average_Decimal_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(decimal)))
});
private static readonly MethodInfo _average_DecimalNullable_Selector = GetMethod(
"Average", (T) => new[]
{
typeof(IQueryable<>).MakeGenericType(T),
typeof(Expression<>).MakeGenericType(typeof(Func<,>).MakeGenericType(T, typeof(decimal?)))
});
#endif
#endregion
#region Include
/// <summary>
/// Specifies the related objects to include in the query results.
/// </summary>
/// <remarks>
/// This extension method calls the Include(String) method of the source <see cref="IQueryable{T}" /> object,
/// if such a method exists. If the source <see cref="IQueryable{T}" /> does not have a matching method,
/// then this method does nothing. The <see cref="ObjectQuery{T}" />, <see cref="ObjectSet{T}" />,
/// <see cref="DbQuery{TResult}" /> and <see cref="DbSet{T}" /> types all have an appropriate Include method to call.
/// Paths are all-inclusive. For example, if an include call indicates Include("Orders.OrderLines"), not only will
/// OrderLines be included, but also Orders. When you call the Include method, the query path is only valid on
/// the returned instance of the <see cref="IQueryable{T}" />. Other instances of <see cref="IQueryable{T}" />
/// and the object context itself are not affected. Because the Include method returns the query object,
/// you can call this method multiple times on an <see cref="IQueryable{T}" /> to specify multiple paths for the query.
/// </remarks>
/// <typeparam name="T"> The type of entity being queried. </typeparam>
/// <param name="source">
/// The source <see cref="IQueryable{T}" /> on which to call Include.
/// </param>
/// <param name="path"> The dot-separated list of related objects to return in the query results. </param>
/// <returns>
/// A new <see cref="IQueryable{T}" /> with the defined query path.
/// </returns>
public static IQueryable<T> Include<T>(this IQueryable<T> source, string path)
{
Check.NotNull(source, "source");
Check.NotEmpty(path, "path");
// Explicitly not checking the value of path since we don't care for the extension method.
// We could use dynamic here, but the problem is that we want to do nothing if the method
// isn't found or is somehow incompatible, which appears to involve catching the RuntimeBinderException
// and ignoring it, which isn't great. Also, if only the return type of the Include method is wrong,
// then using dynamic will still result in the method being called before the exception is thrown.
// Special case the types we know about to avoid reflection, then use reflection for any other
// IQueryable that has an Include method.
var asDbQuery = source as DbQuery<T>;
if (asDbQuery != null)
{
return asDbQuery.Include(path);
}
var asObjectQuery = source as ObjectQuery<T>;
if (asObjectQuery != null)
{
return asObjectQuery.Include(path);
}
return CommonInclude(source, path);
}
/// <summary>
/// Specifies the related objects to include in the query results.
/// </summary>
/// <remarks>
/// This extension method calls the Include(String) method of the source <see cref="IQueryable" /> object,
/// if such a method exists. If the source <see cref="IQueryable" /> does not have a matching method,
/// then this method does nothing. The <see cref="ObjectQuery" />, <see cref="ObjectSet{T}" />,
/// <see cref="DbQuery" /> and <see cref="DbSet" /> types all have an appropriate Include method to call.
/// Paths are all-inclusive. For example, if an include call indicates Include("Orders.OrderLines"), not only will
/// OrderLines be included, but also Orders. When you call the Include method, the query path is only valid on
/// the returned instance of the <see cref="IQueryable" />. Other instances of <see cref="IQueryable" />
/// and the object context itself are not affected. Because the Include method returns the query object,
/// you can call this method multiple times on an <see cref="IQueryable" /> to specify multiple paths for the query.
/// </remarks>
/// <param name="source">
/// The source <see cref="IQueryable" /> on which to call Include.
/// </param>
/// <param name="path"> The dot-separated list of related objects to return in the query results. </param>
/// <returns>
/// A new <see cref="IQueryable" /> with the defined query path.
/// </returns>
public static IQueryable Include(this IQueryable source, string path)
{
Check.NotNull(source, "source");
Check.NotEmpty(path, "path");
// Explicitly not checking the value of path since we don't care for the extension method.
// We could use dynamic here, but the problem is that we want to do nothing if the method
// isn't found or is somehow incompatible, which appears to involve catching the RuntimeBinderException
// and ignoring it, which isn't great. Also, if only the return type of the Include method is wrong,
// then using dynamic will still result in the method being called before the exception is thrown.
// Special case the types we know about to avoid reflection, then use reflection for any other
// IQueryable that has an Include method.
var asDbQuery = source as DbQuery;
return asDbQuery != null ? asDbQuery.Include(path) : CommonInclude(source, path);
}
// <summary>
// Common code for generic and non-generic string Include.
// </summary>
private static T CommonInclude<T>(T source, string path)
{
DebugCheck.NotNull((object)source);
var includeMethod = source.GetType().GetRuntimeMethod(
"Include",
p => p.IsPublic && !p.IsStatic,
new[] { typeof(string) },
new[] { typeof(IComparable) },
new[] { typeof(ICloneable) },
new[] { typeof(IComparable<string>) },
new[] { typeof(IEnumerable<char>) },
new[] { typeof(IEnumerable) },
new[] { typeof(IEquatable<string>) },
new[] { typeof(object) });
if (includeMethod != null
&& typeof(T).IsAssignableFrom(includeMethod.ReturnType))
{
return (T)includeMethod.Invoke(source, new object[] { path });
}
return source;
}
/// <summary>
/// Specifies the related objects to include in the query results.
/// </summary>
/// <remarks>
/// The path expression must be composed of simple property access expressions together with calls to Select for
/// composing additional includes after including a collection proprty. Examples of possible include paths are:
/// To include a single reference: query.Include(e => e.Level1Reference)
/// To include a single collection: query.Include(e => e.Level1Collection)
/// To include a reference and then a reference one level down: query.Include(e => e.Level1Reference.Level2Reference)
/// To include a reference and then a collection one level down: query.Include(e => e.Level1Reference.Level2Collection)
/// To include a collection and then a reference one level down: query.Include(e => e.Level1Collection.Select(l1 => l1.Level2Reference))
/// To include a collection and then a collection one level down: query.Include(e => e.Level1Collection.Select(l1 => l1.Level2Collection))
/// To include a collection and then a reference one level down: query.Include(e => e.Level1Collection.Select(l1 => l1.Level2Reference))
/// To include a collection and then a collection one level down: query.Include(e => e.Level1Collection.Select(l1 => l1.Level2Collection))
/// To include a collection, a reference, and a reference two levels down: query.Include(e => e.Level1Collection.Select(l1 => l1.Level2Reference.Level3Reference))
/// To include a collection, a collection, and a reference two levels down: query.Include(e => e.Level1Collection.Select(l1 => l1.Level2Collection.Select(l2 => l2.Level3Reference)))
/// This extension method calls the Include(String) method of the source IQueryable object, if such a method exists.
/// If the source IQueryable does not have a matching method, then this method does nothing.
/// The Entity Framework ObjectQuery, ObjectSet, DbQuery, and DbSet types all have an appropriate Include method to call.
/// When you call the Include method, the query path is only valid on the returned instance of the IQueryable<T>. Other
/// instances of IQueryable<T> and the object context itself are not affected. Because the Include method returns the
/// query object, you can call this method multiple times on an IQueryable<T> to specify multiple paths for the query.
/// </remarks>
/// <typeparam name="T"> The type of entity being queried. </typeparam>
/// <typeparam name="TProperty"> The type of navigation property being included. </typeparam>
/// <param name="source"> The source IQueryable on which to call Include. </param>
/// <param name="path"> A lambda expression representing the path to include. </param>
/// <returns>
/// A new IQueryable<T> with the defined query path.
/// </returns>
[SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")]
[SuppressMessage("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters")]
public static IQueryable<T> Include<T, TProperty>(
this IQueryable<T> source, Expression<Func<T, TProperty>> path)
{
Check.NotNull(source, "source");
Check.NotNull(path, "path");
string include;
if (!DbHelpers.TryParsePath(path.Body, out include)
|| include == null)
{
throw new ArgumentException(Strings.DbExtensions_InvalidIncludePathExpression, "path");
}
return Include(source, include);
}
#endregion
#region AsNoTracking
/// <summary>
/// Returns a new query where the entities returned will not be cached in the <see cref="DbContext" />
/// or <see cref="ObjectContext" />. This method works by calling the AsNoTracking method of the
/// underlying query object. If the underlying query object does not have an AsNoTracking method,
/// then calling this method will have no affect.
/// </summary>
/// <typeparam name="T"> The element type. </typeparam>
/// <param name="source"> The source query. </param>
/// <returns> A new query with NoTracking applied, or the source query if NoTracking is not supported. </returns>
public static IQueryable<T> AsNoTracking<T>(this IQueryable<T> source) where T : class
{
Check.NotNull(source, "source");
var asDbQuery = source as DbQuery<T>;
return asDbQuery != null ? asDbQuery.AsNoTracking() : CommonAsNoTracking(source);
}
/// <summary>
/// Returns a new query where the entities returned will not be cached in the <see cref="DbContext" />
/// or <see cref="ObjectContext" />. This method works by calling the AsNoTracking method of the
/// underlying query object. If the underlying query object does not have an AsNoTracking method,
/// then calling this method will have no affect.
/// </summary>
/// <param name="source"> The source query. </param>
/// <returns> A new query with NoTracking applied, or the source query if NoTracking is not supported. </returns>
public static IQueryable AsNoTracking(this IQueryable source)
{
Check.NotNull(source, "source");
var asDbQuery = source as DbQuery;
return asDbQuery != null ? asDbQuery.AsNoTracking() : CommonAsNoTracking(source);
}
// <summary>
// Common code for generic and non-generic AsNoTracking.
// </summary>
private static T CommonAsNoTracking<T>(T source) where T : class
{
DebugCheck.NotNull(source);
var asObjectQuery = source as ObjectQuery;
if (asObjectQuery != null)
{
return (T)DbHelpers.CreateNoTrackingQuery(asObjectQuery);
}
var noTrackingMethod = source.GetType().GetPublicInstanceMethod("AsNoTracking");
if (noTrackingMethod != null
&& typeof(T).IsAssignableFrom(noTrackingMethod.ReturnType))
{
return (T)noTrackingMethod.Invoke(source, null);
}
return source;
}
#endregion
#region AsStreaming
/// <summary>
/// Returns a new query that will stream the results instead of buffering. This method works by calling
/// the AsStreaming method of the underlying query object. If the underlying query object does not have
/// an AsStreaming method, then calling this method will have no affect.
/// </summary>
/// <typeparam name="T">
/// The type of the elements of <paramref name="source" />.
/// </typeparam>
/// <param name="source">
/// An <see cref="IQueryable{T}" /> to apply AsStreaming to.
/// </param>
/// <returns> A new query with AsStreaming applied, or the source query if AsStreaming is not supported. </returns>
[Obsolete("LINQ queries are now streaming by default unless a retrying ExecutionStrategy is used. Calling this method will have no effect.")]
public static IQueryable<T> AsStreaming<T>(this IQueryable<T> source)
{
Check.NotNull(source, "source");
var asDbQuery = source as DbQuery<T>;
return asDbQuery != null ? asDbQuery.AsStreaming() : CommonAsStreaming(source);
}
/// <summary>
/// Returns a new query that will stream the results instead of buffering. This method works by calling
/// the AsStreaming method of the underlying query object. If the underlying query object does not have
/// an AsStreaming method, then calling this method will have no affect.
/// </summary>
/// <param name="source">
/// An <see cref="IQueryable" /> to apply AsStreaming to.
/// </param>
/// <returns> A new query with AsStreaming applied, or the source query if AsStreaming is not supported. </returns>
[Obsolete("LINQ queries are now streaming by default unless a retrying ExecutionStrategy is used. Calling this method will have no effect.")]
public static IQueryable AsStreaming(this IQueryable source)
{
Check.NotNull(source, "source");
var asDbQuery = source as DbQuery;
return asDbQuery != null ? asDbQuery.AsStreaming() : CommonAsStreaming(source);
}
private static T CommonAsStreaming<T>(T source) where T : class
{
DebugCheck.NotNull(source);
var asObjectQuery = source as ObjectQuery;
if (asObjectQuery != null)
{
return (T)DbHelpers.CreateStreamingQuery(asObjectQuery);
}
var asStreamingMethod = source.GetType().GetPublicInstanceMethod("AsStreaming");
if (asStreamingMethod != null
&& typeof(T).IsAssignableFrom(asStreamingMethod.ReturnType))
{
return (T)asStreamingMethod.Invoke(source, null);
}
return source;
}
#endregion
#region WithExecutionStrategy
// These methods allow an internal way to change the execution strategy for a particular query
// When making it public all other places where execution strategy is used need to be changed too
internal static IQueryable<T> WithExecutionStrategy<T>(this IQueryable<T> source, IDbExecutionStrategy executionStrategy)
{
Check.NotNull(source, "source");
var asDbQuery = source as DbQuery<T>;
return asDbQuery != null
? asDbQuery.WithExecutionStrategy(executionStrategy)
: CommonWithExecutionStrategy(source, executionStrategy);
}
internal static IQueryable WithExecutionStrategy(this IQueryable source, IDbExecutionStrategy executionStrategy)
{
Check.NotNull(source, "source");
var asDbQuery = source as DbQuery;
return asDbQuery != null
? asDbQuery.WithExecutionStrategy(executionStrategy)
: CommonWithExecutionStrategy(source, executionStrategy);
}
private static T CommonWithExecutionStrategy<T>(T source, IDbExecutionStrategy executionStrategy) where T : class
{
DebugCheck.NotNull(source);
var asObjectQuery = source as ObjectQuery;
if (asObjectQuery != null)
{
return (T)DbHelpers.CreateQueryWithExecutionStrategy(asObjectQuery, executionStrategy);
}
var asStreamingMethod = source.GetType().GetPublicInstanceMethod("WithExecutionStrategy");
if (asStreamingMethod != null
&& typeof(T).IsAssignableFrom(asStreamingMethod.ReturnType))
{
return (T)asStreamingMethod.Invoke(source, new object[] { executionStrategy });
}
return source;
}
#endregion
#region Load
/// <summary>
/// Enumerates the query such that for server queries such as those of <see cref="DbSet{T}" />,
/// <see
/// cref="ObjectSet{T}" />
/// ,
/// <see cref="ObjectQuery{T}" />, and others the results of the query will be loaded into the associated
/// <see
/// cref="DbContext" />
/// ,
/// <see cref="ObjectContext" /> or other cache on the client.
/// This is equivalent to calling ToList and then throwing away the list without the overhead of actually creating the list.
/// </summary>
/// <param name="source"> The source query. </param>
public static void Load(this IQueryable source)
{
Check.NotNull(source, "source");
var enumerator = source.GetEnumerator();
try
{
while (enumerator.MoveNext())
{
}
}
finally
{
var asDisposable = enumerator as IDisposable;
if (asDisposable != null)
{
asDisposable.Dispose();
}
}
}
#if !NET40
/// <summary>
/// Asynchronously enumerates the query such that for server queries such as those of <see cref="DbSet{T}" />,
/// <see
/// cref="ObjectSet{T}" />
/// ,
/// <see cref="ObjectQuery{T}" />, and others the results of the query will be loaded into the associated
/// <see
/// cref="DbContext" />
/// ,
/// <see cref="ObjectContext" /> or other cache on the client.
/// This is equivalent to calling ToList and then throwing away the list without the overhead of actually creating the list.
/// </summary>
/// <param name="source"> The source query. </param>
/// <returns>
/// A task that represents the asynchronous operation.
/// </returns>
public static Task LoadAsync(this IQueryable source)
{
Check.NotNull(source, "source");
return source.LoadAsync(CancellationToken.None);
}
/// <summary>
/// Asynchronously enumerates the query such that for server queries such as those of <see cref="DbSet{T}" />,
/// <see
/// cref="ObjectSet{T}" />
/// ,
/// <see cref="ObjectQuery{T}" />, and others the results of the query will be loaded into the associated
/// <see
/// cref="DbContext" />
/// ,
/// <see cref="ObjectContext" /> or other cache on the client.
/// This is equivalent to calling ToList and then throwing away the list without the overhead of actually creating the list.
/// </summary>
/// <param name="source"> The source query. </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
/// </param>
/// <returns>
/// A task that represents the asynchronous operation.
/// </returns>
public static Task LoadAsync(this IQueryable source, CancellationToken cancellationToken)
{
Check.NotNull(source, "source");
return source.ForEachAsync(e => { }, cancellationToken);
}
#endif
#endregion
#region ForEachAsync
#if !NET40
/// <summary>
/// Asynchronously enumerates the query results and performs the specified action on each element.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <param name="source">
/// An <see cref="IQueryable" /> to enumerate.
/// </param>
/// <param name="action"> The action to perform on each element. </param>
/// <returns> A task that represents the asynchronous operation. </returns>
public static Task ForEachAsync(this IQueryable source, Action<object> action)
{
Check.NotNull(source, "source");
Check.NotNull(action, "action");
return source.AsDbAsyncEnumerable().ForEachAsync(action, CancellationToken.None);
}
/// <summary>
/// Asynchronously enumerates the query results and performs the specified action on each element.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <param name="source">
/// An <see cref="IQueryable" /> to enumerate.
/// </param>
/// <param name="action"> The action to perform on each element. </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
/// </param>
/// <returns> A task that represents the asynchronous operation. </returns>
public static Task ForEachAsync(this IQueryable source, Action<object> action, CancellationToken cancellationToken)
{
Check.NotNull(source, "source");
Check.NotNull(action, "action");
return source.AsDbAsyncEnumerable().ForEachAsync(action, cancellationToken);
}
/// <summary>
/// Asynchronously enumerates the query results and performs the specified action on each element.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <typeparam name="T">
/// The type of the elements of <paramref name="source" />.
/// </typeparam>
/// <param name="source">
/// An <see cref="IQueryable{T}" /> to enumerate.
/// </param>
/// <param name="action"> The action to perform on each element. </param>
/// <returns> A task that represents the asynchronous operation. </returns>
public static Task ForEachAsync<T>(this IQueryable<T> source, Action<T> action)
{
Check.NotNull(source, "source");
Check.NotNull(action, "action");
return source.AsDbAsyncEnumerable().ForEachAsync(action, CancellationToken.None);
}
/// <summary>
/// Asynchronously enumerates the query results and performs the specified action on each element.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <typeparam name="T">
/// The type of the elements of <paramref name="source" />.
/// </typeparam>
/// <param name="source">
/// An <see cref="IQueryable{T}" /> to enumerate.
/// </param>
/// <param name="action"> The action to perform on each element. </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
/// </param>
/// <returns> A task that represents the asynchronous operation. </returns>
public static Task ForEachAsync<T>(this IQueryable<T> source, Action<T> action, CancellationToken cancellationToken)
{
Check.NotNull(source, "source");
Check.NotNull(action, "action");
return source.AsDbAsyncEnumerable().ForEachAsync(action, cancellationToken);
}
#endif
#endregion
#region Async equivalents of IEnumerable extension methods
#if !NET40
/// <summary>
/// Creates a <see cref="List{Object}" /> from an <see cref="IQueryable" /> by enumerating it asynchronously.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <param name="source">
/// An <see cref="IQueryable" /> to create a <see cref="List{Object}" /> from.
/// </param>
/// <returns>
/// A task that represents the asynchronous operation.
/// The task result contains a <see cref="List{Object}" /> that contains elements from the input sequence.
/// </returns>
[SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")]
public static Task<List<object>> ToListAsync(this IQueryable source)
{
Check.NotNull(source, "source");
return source.AsDbAsyncEnumerable().ToListAsync<object>();
}
/// <summary>
/// Creates a <see cref="List{Object}" /> from an <see cref="IQueryable" /> by enumerating it asynchronously.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <param name="source">
/// An <see cref="IQueryable" /> to create a <see cref="List{Object}" /> from.
/// </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
/// </param>
/// <returns>
/// A task that represents the asynchronous operation.
/// The task result contains a <see cref="List{Object}" /> that contains elements from the input sequence.
/// </returns>
[SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")]
public static Task<List<object>> ToListAsync(this IQueryable source, CancellationToken cancellationToken)