Concat两个具有匿名类型的IQueryables? [英] Concat Two IQueryables with Anonymous Types?

问题描述

我已经努力了好一阵子，而且开始看起来似乎不可能.

I've been wrestling with this a little while and it's starting to look like it may not be possible.

我要Concat()两个IQueryable，然后将结果作为单个查询执行.我尝试过这样的事情:

I want to Concat() two IQueryables and then execute the result as a single query. I tried something like this:

var query = from x in ...
select new
{
    A = ...
    B = ...
    C = ...
};

var query2 = from y in ...
select new
{
    A = ...
    B = ...
    C = ...
};

var query3 = query.Concat(query2);

但是，最后一行给我以下错误:

However, the last line gives me the following error:

'System.Linq.IQueryable'不包含'Concat'的定义，最佳扩展方法重载'System.Linq.ParallelEnumerable.Concat(System.Linq.ParallelQuery，System.Collections.Generic.IEnumerable)'具有一些无效的参数

'System.Linq.IQueryable' does not contain a definition for 'Concat' and the best extension method overload 'System.Linq.ParallelEnumerable.Concat(System.Linq.ParallelQuery, System.Collections.Generic.IEnumerable)' has some invalid arguments

似乎该参数期望为IEnumerable.有什么办法解决吗?

It appears it's expecting an IEnumerable for the argument. Is there any way around this?

看起来我可以将两个查询都解析为IEnumerable s，然后将它们解析为Concat().但是创建单个查询会更有效，而且似乎应该可行.

It looks like I could resolve both queries to IEnumerables and then Concat() them. But it would be more efficient to create a single query, and it seems like that should be possible.

推荐答案

正如您之前在评论中所述，看来这两个查询返回的对象不同:

As you said previously in the comments, it seems that the two queries return different objects:

查询1(根据评论):

f__AnonymousTypee<Leo.Domain.FileItem,Leo.Domain.Employ‌​ee,int,string,string>

Query2是

f__AnonymousTypee<Leo.Domain.FileItem,L‌​eo.Domain.Employee,int?,string,string>

这就是为什么Concat会向您显示一条错误消息，抱怨参数无效.

This is why Concat is giving you an error message complaining about invalid arguments.

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