4.0的EntityFramework&.CreateQuery LT; T>和排序依据例外

问题描述

我认为这固定在4.0。我有这样的方法

 公开的IQueryable< T>所有（表达式来; Func键< T，对象>>排序）
 {
返回EntityContext.CreateQuery< T>（实体名称）.AsQueryable< T>（）排序依据（排序）。 
} 
  

这抛出以下异常

Any idea how to fix this or if there's any workaroundThis happens with every call when the order is not a string datatype

IQueryable<Blog> sortedAll = _repository.All(x => x.Title);

since Title is a string the orderBy works fine. but it fails with any other datatypes

Since I came up with this "bad" solution before I seen Marc's. I thought I post it

public IQueryable<T> All(Expression<Func<T,object>> sort)
    {

        var expresssionType = sort.Body.GetType();
       string propertyName= expresssionType == typeof(System.Linq.Expressions.UnaryExpression) ? ((MemberExpression)((UnaryExpression)sort.Body).Operand).Member.Name : ((MemberExpression)sort.Body).Member.Name;
        var items=   EntityContext.CreateQuery<T>(EntityName).AsQueryable<T>();
        var type = typeof(T);
        var expressionProperty = type.GetProperty(propertyName);
        var exPressionparameter = Expression.Parameter(type, "p");
        var propertyAccess = Expression.MakeMemberAccess(exPressionparameter, expressionProperty);
        var orderByExp = Expression.Lambda(propertyAccess, exPressionparameter);
        Expression resultExp = Expression.Call(typeof(Queryable), "OrderBy", new Type[] { type, expressionProperty.PropertyType }, items.Expression, Expression.Quote(orderByExp));
        return items.AsQueryable().Provider.CreateQuery<T>(resultExp);
    }

解决方案

I can't change the runtime, but can't you just work around it? i.e.

public IQueryable<T> All<TValue>(Expression<Func<T,TValue>> sort)
{
    return EntityContext.CreateQuery<T>(EntityName)
           .AsQueryable<T>().OrderBy<T,TValue>(sort);
}

and

IQueryable<Blog> sortedAll = _repository.All(x => x.SomeProp);

?

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