我正在尝试将动态生成的LambdaExpression传递给IncludeFilter，如下所示：
编辑：我已将测试代码更改为以下内容，因为（正确）我没有实现我的“Where”语句。正在生成正确的where语句，但我无法将lambda语句传递给IncludeFilter调用：
DbSet<MyTestEntity> dbSet = db.Set<MyTestEntity>();
ParameterExpression parameter = Expression.Parameter(typeof(MyTestEntity), "t");
Expression idProperty = Expression.Property(parameter, "mytestentityid");
Expression delProperty = Expression.Property(parameter, "deleted");
Expression delTarget = Expression.Constant(false, typeof(bool));
Expression deletedMethod = Expression.Call(delProperty, "Equals", null, delTarget);
Expression<Func<MyTestEntity, bool>> lambda = Expression.Lambda<Func<MyTestEntity, bool>>(deletedMethod, parameter);
IQueryable<MyTestEntity> query = dbSet.Where(lambda);
Console.WriteLine("Current Query: {0}", query.ToString());
foreach (string include in includes)
{
Type subType = db.GetType().Assembly.GetTypes().SingleOrDefault(x => x.Name.EndsWith(include));
Assert.IsNotNull(subType);
ParameterExpression innerParam = Expression.Parameter(subType, subType.Name);
Assert.IsNotNull(innerParam);
MemberExpression inrDelProp = Expression.Property(innerParam, "deleted");
Assert.IsNotNull(inrDelProp);
ConstantExpression inrDelCstProp = Expression.Constant(false, typeof(bool));
Assert.IsNotNull(inrDelCstProp);
MethodCallExpression inrDelMthd = Expression.Call(inrDelProp, "Equals", null, inrDelCstProp);
Assert.IsNotNull(inrDelMthd);
var delegateType = typeof(Func<,>).MakeGenericType(subType, typeof(bool));
dynamic inrLmbdaExpr = Expression.Lambda(delegateType, inrDelMthd, innerParam);
Assert.IsNotNull(inrLmbdaExpr);
Console.WriteLine("inrLmbdaExpr: {0}", inrLmbdaExpr.ToString()); // Result: MyTestEntityChild => MyTestEntityChild.deleted.Equals(false)
query = query.IncludeFilter(inrLmbdaExpr); // ERROR HERE
Assert.IsNotNull(query);
Console.WriteLine("-------------------------------------------------");
Console.WriteLine("Current Query: {0}", query.ToString());
}
它构建在一个抽象类中，允许我传入实体类型，检索记录，并重用该方法而不管实体类型如何;但是，我也试图过滤掉标记为已删除的子实体（因此使用EF +）。
我该怎么做？
编辑2：所以，我意识到我的解决方案中也有Linq.Dynamic.Core（！），因此我已经有权从字符串中解析LambdaExpression。但是，我得到的错误说IncludeFilter不知道它试图使用哪种方法。 （我在对象浏览器中看到一个使用Expression＆gt;并且一个使用Expression＆gt;＆gt;。如果我能弄清楚如何让IncludeFilter识别哪个方法，我想我会完成！这是代码示例我改写了： string myIncStr = String.Format("x => x.{0}.Where(s => s.deleted.Equals(false)).Where(x => x.MyEntityId.Equals(IncomingId)",includedEntityName);
IEnumerable<MyEntity> result = db.MyEntity.IncludeFilter(System.Linq.Dynamic.Core.DynamicExpressionParser.ParseLambda(typeof(MyChildEntity), myIncStr, null));
有没有办法“强制”（缺少更好的术语）IncludeFilter使用一种方法？是通过在Parser中传递值而不是null吗？
顺便说一下，谢谢你的帮助。您的EFP库实际上非常出色。答案 0 :(得分：0)
免责声明：我是该项目的所有者Entity Framework Plus
是的，这是可能的，但前提是您可以为QueryFilter明确指定方法所需的通用参数类型（正如您在评论中提到的那样）。
否则，您还需要通过表达式调用QueryFilter以使一切变得通用。
但是，您当前的表达式似乎有一些错误，例如不调用Where方法。
您想要达到的目标可能类似于此：
query = query.IncludeFilter(x => x.Childs.Where(y => !y.Deleted));
免责声明：我是该项目的所有者Eval-Expression.NET
此库不是免费的，但可以更轻松，更快速地使用动态表达式。
一旦使用，您可以像通常编写LINQ一样在几行中快速创建动态表达式。这是一个代码，可以处理类似的情况：
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Windows.Forms;
using Z.Expressions;
namespace Z.EntityFramework.Plus.Lab.EF6
{
public partial class Form_Request_IncludeFilter_Dynamic : Form
{
public Form_Request_IncludeFilter_Dynamic()
{
InitializeComponent();
// CLEAN
using (var context = new EntityContext())
{
context.MyEntityClasses.RemoveRange(context.MyEntityClasses);
context.MyEntityClassToFilters.RemoveRange(context.MyEntityClassToFilters);
context.SaveChanges();
}
// SEED
using (var context = new EntityContext())
{
var entity1 = context.MyEntityClasses.Add(new MyEntityClass {ColumnInt = 1, Childs = new List<MyEntityClassToFilter>()});
entity1.Childs.Add(new MyEntityClassToFilter {ColumnInt = 1, Deleted = true});
entity1.Childs.Add(new MyEntityClassToFilter {ColumnInt = 2, Deleted = false});
context.MyEntityClasses.Add(new MyEntityClass {ColumnInt = 2});
context.MyEntityClasses.Add(new MyEntityClass {ColumnInt = 3});
context.SaveChanges();
}
// TEST
using (var context = new EntityContext())
{
// You must register extension method only once
// That should not be done here, but for example purpose
EvalManager.DefaultContext.RegisterExtensionMethod(typeof(QueryIncludeFilterExtensions));
// That could be also dynamic. I believe you already handle this part
IQueryable<MyEntityClass> query = context.MyEntityClasses;
// The path to include
var include = "Childs";
// The dynamic expression to execute
var dynamicExpression = "IncludeFilter(x => x." + include + ".Where(y => !y.Deleted));";
query = query.Execute<IQueryable<MyEntityClass>>(dynamicExpression);
// The result
var list = query.ToList();
}
}
public class EntityContext : DbContext
{
public EntityContext() : base("CodeFirstEntities")
{
}
public DbSet<MyEntityClass> MyEntityClasses { get; set; }
public DbSet<MyEntityClassToFilter> MyEntityClassToFilters { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Types().Configure(x =>
x.ToTable(GetType().DeclaringType != null
? GetType().DeclaringType.FullName.Replace(".", "_") + "_" + x.ClrType.Name
: ""));
base.OnModelCreating(modelBuilder);
}
}
public class MyEntityClass
{
public int ID { get; set; }
public int ColumnInt { get; set; }
public List<MyEntityClassToFilter> Childs { get; set; }
}
public class MyEntityClassToFilter
{
public int ID { get; set; }
public int ColumnInt { get; set; }
public bool Deleted { get; set; }
}
}
}
编辑：回答问题
请查看我更改的代码
您仍然缺少where条款。
您所拥有的内容与您评论的相似
// Result: MyTestEntityChild => MyTestEntityChild.deleted.Equals(false)
你想要的是与此类似的东西
// Result: MyTestEntityChild => MyTestEntityChild.Where(x => x.deleted.Equals(false))
编辑：回答问题
对不起，我现在明白了它的问题。
如果您不知道类型，则需要在表达式中调用IncludeFilter以使一切都通用。它不能像你想要的那样被明确地称为。