自引用循环导致 map 堆栈溢出

Question

根据文档，应尽可能为 AutoMapper 自动设置 PreserveReferences。

Starting from 6.1.0 PreserveReferences is set automatically at config time whenever possible.

https://github.com/AutoMapper/AutoMapper/wiki/5.0-Upgrade-Guide

我也试过将 MaxDepth 设置为 1，但我仍然遇到以下映射的堆栈溢出异常。我能以某种方式解决这个问题还是需要修改视图模型？

cfg.CreateMap<ArticleViewModel, Article>(MemberList.Source)
    .MaxDepth(1)
    .EqualityComparison((src, dst) => src.Id == dst.Id);

导致堆栈溢出异常的代码：

var article = await iArticleRepository.GetAsync(id);
//The mapping below causes the exception
var mappedArticle = Mapper.Map<ArticleViewModel>(article);

实体：

public class Article: IEntity<int>
{
    [Key]
    public int Id { get; set; }

    ...

    public int SupplierId { get; set; }

    public virtual Supplier Supplier { get; set; }
}

public class Supplier: IEntity<int>
{
    [Key]
    public int Id { get; set; }

    ...

    public virtual ICollection<Contact> Contacts { get; set; }
}

public class Contact: IEntity<int>
{
    [Key]
    public int Id { get; set; }

    ...
    public virtual ICollection<Supplier> Suppliers { get; set; }
}

查看型号：

public class ArticleViewModel
{
    public int Id { get; set; }

    ...
    public SupplierViewModel Supplier { get; set; }

}

public class SupplierViewModel
{
    public int Id { get; set; }

    ...
    public List<ContactViewModel> Contacts { get; set; }

}

public class ContactViewModel
{
    public int Id { get; set; }
    ... 
    public List<SupplierViewModel> Suppliers { get; set; }
}

Answer 1

嗯，不清楚 只要有可能 是什么意思。由于之前的文档指出

It turns out this tracking is very expensive, and you need to opt-in using PreserveReferences for circular maps to work

看起来你的场景不符合不可能类别:)

不要依赖它并使用显式选择加入。此示例模型中的循环引用位于 Supplier 和 Contact 之间，因此您必须在涉及的 class 映射之一中指定，例如：

cfg.CreateMap<ArticleViewModel, Article>(MemberList.Source)
    .MaxDepth(1)
    .EqualityComparison((src, dst) => src.Id == dst.Id);

cfg.CreateMap<SupplierViewModel, Supplier>(MemberList.Source)
    .PreserveReferences()
    .EqualityComparison((src, dst) => src.Id == dst.Id);

自引用循环导致 map 堆栈溢出

Self referencing loop causing stack overflow with map

c#

entity-framework

automapper

automapper-6