如何解决 - 无法使用Automapper将Generic.List转换为Linq.IQueryable？ [英] How to resolve - unable to cast Generic.List to Linq.IQueryable using Automapper?

问题描述

使用DTO和EF模型时，我收到以下错误：

I'm getting the following error in using a DTO and EF model:

无法投射类型为
的对象'System.Collections.Generic.List 1 [Project.Core.UI.Models.ContentTypes]'
键入'System.Linq.IQueryable 1 [项目。 Core.UI.Models.ContentTypes]

Unable to cast object of type 'System.Collections.Generic.List1[Project.Core.UI.Models.ContentTypes]' to type 'System.Linq.IQueryable1[Project.Core.UI.Models.ContentTypes]

引导： Mapper.CreateMap< ContentType，Project.Core.UI .Models.ContentTypes>（）;

在一个OData控制器方法 public IQueryable< ContentTypes> Get（）{...} ，使用：

In an OData controller method public IQueryable<ContentTypes> Get() {...}, using:

var result = Mapper.Map<IQueryable<ContentType>, IQueryable<ContentTypes>>(_repository.Query().Get()
    .Where(u => u.UserId == userId)
    .OrderBy(o => o.Description));

我也尝试了以下内容，但我怀疑这正是上面的一样： / p>

I have also tried the following but I suspect that this is exactly what the above is as well:

var result =_repository.Query().Get()
    .Where(u => u.UserId == userId)
    .OrderBy(o => o.Description);
var dto = Mapper.Map<IQueryable<ContentType>, IQueryable<ContentTypes>>(result);
return dto;

如何为此创建适当的映射？

How can I create the appropriate mapping for this?

推荐答案

您需要注意的事实是，通过以下方式创建映射：

You need to be aware of the fact that by creating your mapping in such a way:

Mapper.CreateMap<ContentType, Project.Core.UI.Models.ContentTypes>();

只有这些基本的通用集合类型才能被隐含地支持：

Only these basic generic collection types are supported implicitly:

IEnumerable
IEnumerable<T>
ICollection
ICollection<T>
IList
IList<T>
List<T>
Arrays

但不是 IQueryable< T> 。这就是为什么你得到例外。

But not IQueryable<T>. That's why you get the exception.

所以你应该尝试这样做：

Therefore you should try doing sth like this:

var dto = Mapper.Map
         <IEnumerable<ContentType>, 
          IEnumerable<ContentTypes>>(result.AsEnumerable()); 
// or e.g. List/List/ToList()

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