是否可以映射IQueryable< CatDTO>到IQueryable< CatEf>？ [英] Is it possible to map IQueryable<CatDTO> to IQueryable<CatEf>?

问题描述

这是Automapper专业人士的一个问题。我已经尝试了几天的查询映射 - 没有运气。就像Automapper似乎不是要用我想要使用的方式。但也许我错了。所以这里是问题...

This is a question for Automapper professionals. I have tried to do query mapping for several days already - and no luck. Seems like Automapper is not intended to be used the way I want to use it. But maybe I am wrong. So here is the question...

我有这样的课程：

• CatDto（名称，年龄，玩具（ToyDto对象的收藏））


• ToyDto（CatName，ToyName，Cat（parent CatDto object））

< （来自实体框架，具有与CatDto类似的属性）

• 玩具（来自实体框架，具有与ToyDto类似的属性）

• CatDto (Name, Age, Toys (collection of ToyDto objects))
• ToyDto (CatName, ToyName, Cat (parent CatDto object))
• Cat (comes from Entity Framework, has properties similar to those in CatDto)
• Toy (comes from Entity Framework, has properties similar to those in ToyDto)

我想在我的数据访问层写一个通用的读取函数，如下所示：

I want to write a generic read function in my data access layer, something like this:

IEnumerable<CatDto> Read(IQueryable<CatDto> query) {
    // here "query" is converted 
    // to Entity Framework query by means of AutoMapper,
    // EF query gets executed,
    // I convert EF entities (Cat) back to CatDto - this is not essential
    // result is returned
}

我将以不同的方式调用此函数。示例：

I will call this function in different manners. Example:

var q = new ObjectModel.Collection(Of CatDto)).AsQueryable();
q = q.Where(c => c.Toys.Count() > 1);
var someResultVar = Read(q);

到目前为止，任何实现此类行为的尝试都失败了。我不知道Automapper是否是这里的帮手，还是我完全错误的方式？

So far any attempts to implement such behavior have failed. I wonder if Automapper is a helper here or am I going completely wrong way?

推荐答案

我相信你想要的功能在< a href =https://github.com/AutoMapper/AutoMapper/wiki/Expression-Translation-(UseAsDataSource） =nofollow> UseAsDataSource

I believe the functionality you want is in UseAsDataSource

您不能映射IQueryable，但是您不应该使用UseAsDataSource
示例

You can't map IQueryable, but you shouldn't need to with UseAsDataSource Example

IQueryable<CatDto> someResultVar  = new ObjectModel.Collection(Of CatDto)).AsQueryable().UseAsDataSource().For(Of OrderLineDTO).Where(c => c.Toys.Count() > 1);

当您枚举它会将Lambda从CatDto转换为CatEf并调用 ProjectTo< CatDto> 并返回CatDto对象

When you enumerate it will convert Lambda from CatDto to CatEf and call ProjectTo<CatDto> and return CatDto objects

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