Question

将EF Core与Automapper结合使用时，我们使结果SQL在同一表上为每个属性进行左连接。

这是我们班级的联系方式-

public class Foo {
    public Bar bar { get; set; }
    public string id { get; set; }
}

public class Bar {
    
    public Bar {
        fooCollection = new HashSet<Foo>();
        childBarCollection = new HashSet<ChildBar >();
    }

    public string id { get; set; }

    private ICollection<Foo> fooCollection { get; set; }

    private ICollection<ChildBar> childBarCollection { get; set; }
}

public class ChildBar {
   public virtual Bar { get; set; }
   public string id { get; set; }
   public string name { get; set; }
}

尝试执行以下调用时，它会导致多个左联接，而我只希望其中一个：

SELECT [c1].[Id], [c1].[Name], [c2].[Id], [c2].[Name],
FROM [dbo].[Foo] AS [i]
INNER JOIN [dbo].[Bar] AS [c] ON [i].[Id] = [c].[Id]
LEFT JOIN [dbo].[ChildBar] AS [c0] ON [c].[Id] = [c0].[Id]
LEFT JOIN [dbo].[ChildBar] AS [c1] ON [c].[Id] = [c1].[Id]

此呼叫如下：

await this.fooRepository.GetQueryable()
    .Include(x => x.Bar).ThenInclude(x => x.ChildBar)
    .ProjectTo<DTOReturn>(this.mapper.ConfigurationProvider)
    .ToListAsync(cancellationToken)
    .ConfigureAwait(false);

对象与数据库之间的映射如下：

FooMap：

builder.HasOne(t => t.bar)
    .WithMany(t => t.fooCollection)
    .HasForeignKey(x => x.Id);

BarMap：

builder.HasMany(t => t.fooCollection)
    .WithOne(t => t.var)
    .HasForeignKey(t => t.Id);

builder.HasMany(t => t.childBarCollection)
    .WithOne(t => t.Bar)
    .HasForeignKey(t => t.Id);

ChildBarMap

builder.HasOne(t => t.bar)
    .WithMany(t => t.childBarCollection)
    .HasForeignKey(d => d.Id);

以下是映射配置文件：

FooMappingProfile

this.CreateMap<Foo, DTOReturn>()
    .ForMember(x => x.DTO2, opts => opts.MapFrom(r => r.Bar))

BarMappingProfile

this.CreateMap<Bar, DTO2>()
    .ForMember(x => x.Id, opts => opts.MapFrom(r => r.ChildBar.Id))
    .ForMember(x => x.Name, opts => opts.MapFrom(r => r.ChildBar.name));

ChildBarMapping ：

this.CreateMap<ChildBar, DTO2>()
    .ForMember(x => x.Id, opts => opts.MapFrom(r => r.Id))
    .ForMember(x => x.Name, opts => opts.MapFrom(r => r.name));

想知道这是否有人遇到过。上面的示例很粗糙，因为我无法提供业务代码，但这可以说明正在发生的事情。

EF核心包括多个左联接

0 个答案: