源子列表AutoMapper对象映射到现有的对象目的地子实体集 [英] AutoMapper mapping objects in source child list to existing objects in destination child entity collection

问题描述

我有以下情况：

public class Parent : EntityObject
{
    EntityCollection<Child> Children { get; set; }
}

public class Child : EntityObject
{
    int Id { get; set; }
    string Value1 { get; set; }
    string Value2 { get; set; }
}

public class ParentViewModel
{
    List<ChildViewModel> Children { get; set; }
}

public class ChildViewModel
{
    int Id { get; set; }
    string Value1 { get; set; }
    string Value2 { get; set; }
}

Mapper.CreateMap<ParentViewModel, Parent>();

Mapper.CreateMap<ChildViewModel, Child>();

时有可能得到AutoMapper为：

Is it possible to get AutoMapper to:

• 在 ParentViewModel.Children 列表地图对象在对象 Parent.Children EntityCollection相匹配的IDS。


• 创建为对象 Parent.Children 新对象 ParentViewModel.Children ，其中来自源ID的对象没有在目的地列表中找到。


• 从 Parent.Children 其中，目标id源列表中不存在。



• Map objects in the ParentViewModel.Children list to objects in the Parent.Children EntityCollection with matching Ids.
• Create new objects in Parent.Children for objects in ParentViewModel.Children where an object with the id from source is not found in the destination list.
• Remove objects from Parent.Children where the destination id does not exist in the source list.

我要对所有这一切错了？

Am I going about this all wrong?

推荐答案

恐怕automapper并不意味着用于映射到填充对象时，它会删除该文Parent.Children调用地图（） 。
。您在这里有几种方法：

I'm afraid automapper is not meant to be used for mapping to a populated object, it will erase the Parent.Children wen you invoke Map(). You have several approaches here:

• 一是创建自己的条件来执行对儿童地图：

• One is to create yourself the condition to execute the map on childrens:

foreach (var childviewmodel in parentviewmodel.Children)
{
    if (!parent.Children.Select(c => c.Id).Contains(childviewmodel.Id))
    {
        parent.Children.Add(Mapper.Map<Child>(childviewmodel));
    }
}

对于其他行为的其他IFS

Other ifs for other behaviour

一是要创造一个IMappingAction，并把它挂在BeforeMap方式：

One is to create an IMappingAction and hook it in the BeforeMap method:

class PreventOverridingOnSameIds : IMappingAction<ParentViewModel, Parent>
{
    public void Process (ParentViewModel source, Parent destination)
    {
        var matching_ids = source.Children.Select(c => c.Id).Intersect(destination.Children.Select(d => d.Id));
        foreach (var id in matching_ids)
        {
            source.Children = source.Children.Where(c => c.Id != id).ToList();
        }
    }
}

..后来就

Mapper.CreateMap<ParentViewModel, Parent>()
    .BeforeMap<PreventOverridingOnSameIds>();

这样，你让automapper做的工作。

this way you let automapper do the job.

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