递归模型的 AutoMapper 条件映射

Question

我有一个递归模型class，其定义如下：

public class ItemFilterBlockGroup
{
    public ItemFilterBlockGroup(string groupName, ItemFilterBlockGroup parent, bool advanced = false)
    {
        GroupName = groupName;
        ParentGroup = parent;
        Advanced = advanced;
        ChildGroups = new List<ItemFilterBlockGroup>();
    }

    public string GroupName { get; private set; }
    public bool Advanced { get; private set; }
    public ItemFilterBlockGroup ParentGroup { get; private set; }
    public List<ItemFilterBlockGroup> ChildGroups { get; private set; }
}

它有一个名为 ChildGroups 的属性，它本身就是一个列表 - 这用于构建分层模型。我想做的是将此模型映射到视图模型，但有条件。有时（取决于 UI 设置）我只想包含 Advanced = false 的子对象，有时我想包含所有模型。

目前，我正在通过涉及 Mapper.Reset() 和运行时重新定义地图的讨厌的 hack 来实现这一目标 - 这显然不好，并且存在多个问题：

Mapper.Reset();
if (showAdvanced)
{
    Mapper.CreateMap<ItemFilterBlockGroup, ItemFilterBlockGroupViewModel>();
}
else
{
    Mapper.CreateMap<ItemFilterBlockGroup, ItemFilterBlockGroupViewModel>()
        .ForMember(dest => dest.ChildGroups,
            opts => opts.MapFrom(from => from.ChildGroups.Where(c => c.Advanced == false)));
}

var mappedViewModels = Mapper.Map<ObservableCollection<ItemFilterBlockGroupViewModel>>(blockGroups);

给定模型输入层次结构示例：

Root (Advanced = False)
+-Child 1 (Advanced = True)
+-Child 2 (Advanced = False)
+-Child 3 (Advanced = False)
  +-Child 3 Sub Child 1 (Advanced = False)
  +-Child 3 Sub Child 2 (Advanced = True)

第一个 CreateMap 定义 returns 此层次结构未受影响，第二个 CreateMap 定义（使用 Advanced 参数）returns 此修改后的层次结构（所有 Advanced = true 模型及其子项都被排除在映射之外):

Root (Advanced = False)
+-Child 2 (Advanced = False)
+-Child 3 (Advanced = False)
  +-Child 3 Sub Child 1 (Advanced = False)

如何参数化 showAdvanced 条件并使用单个 CreateMap 定义获得相同的结果？我搜索了很多正确的解决方案，尝试了 ResolveUsing、CustomResolvers，但无济于事。

Answer 1

您可以使用如下所示的自定义转换器，您可以自定义您的映射设置。

创建转换class

  internal class AccountConverter : TypeConverter<PD.IAccount, OD.IAccount>
{
    protected override OD.IAccount ConvertCore(PD.IAccount source)
    {
        var result = new Account()
        {
            CustomerNumber = source.CustomerNumber,
            EAccount = source.EAccount,
            EmailAddress = source.EmailAddress
        };

        return result;
    }
}

然后像这样添加映射。

Mapper.CreateMap<PD.IAccount, OD.IAccount>()
  .ConvertUsing(new AccountConverter());

Answer 2

好吧，您想使用不属于对象的外部参数来控制逻辑。我相信最好的方法是使用一个映射，并根据您的标志过滤输入对象。像这样

            var blockGroupsTemp;
            if (showAdvanced) 
                blockGroupsTemp = blockGroups;
            else
            {
                blockGroupsTemp = blockGroups.Where(x => x.Advanced == false).ToList();
                blockGroupsTemp.ForEach(s => s.ChildGroups.RemoveAll(y => y.Advanced == true));
            }

            var mappedViewModels = Mapper.Map<ObservableCollection<ItemFilterBlockGroupViewModel>>(blockGroupsTemp);

Answer 3

您可以使用上下文选项 Items 集合在运行时将值传递给映射函数：

var showAdvanced = true;
var mappedViewModels = Mapper.Map<ObservableCollection<ItemFilterBlockGroupViewModel>>(
    blockGroups, 
    options => options.Items["includeAdvanced"] = showAdvanced);

并在上下文可用的任何地方使用它们来构造目标对象。在 ResolveUsing 或 ConstructUsing 方法中，例如：

Mapper.CreateMap<ItemFilterBlockGroup, ItemFilterBlockGroupViewModel>()
    .ForMember(destination => destination.ChildGroups, options => options.ResolveUsing(
        (resolution) =>
        {
            var includeAdvanced = (bool)resolution.Context.Options.Items["includeAdvanced"];
            var source = (ItemFilterBlockGroup)resolution.Context.SourceValue;
            if(includeAdvanced)
                return source.ChildGroups;
            else
                return source.ChildGroups.Where(c => c.Advanced == false);               
         }));

如果使用弱类型字典值来传递标志参数对您来说看起来不太漂亮，我建议将此逻辑封装在两个单独的方法中，如 Martin Fowler article 示例。

递归模型的 AutoMapper 条件映射

AutoMapper conditional map for recursive model

c#

automapper