[英]Nested query in Entity Framework with AutoMapper
用例如下:一个客户帐户只有一个地址,即送货或帐单。 我需要将其合并为一个地址实体。 最重要的是,地址行是数据库中的单独列,但必须是DTO中字符串的IEnumerable。 由于OData必须实现,因此始终都必须支持ProjectTo()。 我如何在不更改数据库的情况下完成此任务? 由于遗留应用程序,我无法碰它。
第一个代码示例有效,而第二个代码示例却失败了: The nested query is not supported. Operation1='Case' Operation2='Collect'
The nested query is not supported. Operation1='Case' Operation2='Collect'
。 这可能是因为它必须创建子实体。 我如何使它工作? 有什么解决方法(也许是重组我的实体)吗?
在第一个示例中,我将不同地址线列的映射添加到List<string>
。 然后,当调用.Include()时,实体框架完全知道该做什么并且可以工作。
public void Main()
{
Mapper.Initialize(cfg =>
{
cfg.CreateMap<ShippingAddress, DtoShippingAddress>
.ForMember(dto => dto.AddressLines,
entity => entity.MapFrom(source => new List<string>
{
source.AddressLine1,
source.AddressLine2,
source.AddressLine3
}));
cfg.CreateMap<BillingAddress, DtoBillingAddress>
.ForMember(dto => dto.AddressLines,
entity => entity.MapFrom(source => new List<string>
{
source.AddressLine1,
source.AddressLine2,
source.AddressLine3
}));
});
Mapper.AssertConfigurationIsValid();
var context = new ClientContext();
var result = context.CustomerAccounts.Include(i => i.ShippingAddress).Include(i => i.BillingAddress).ProjectTo<DtoCustomerAccount>();//.Dump();
}
public class CustomerAccount
{
public int Id { get; set; }
public ShippingAddress ShippingAddress { get; set; }
public BillingAddress BillingAddress { get; set; }
}
public class ShippingAddress
{
public int Id { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string AddressLine3 { get; set; }
}
public class BillingAddress
{
public int Id { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string AddressLine3 { get; set; }
}
public class DtoCustomerAccount
{
public int Id { get; set; }
public DtoShippingAddress ShippingAddress { get; set; }
public DtoBillingAddress BillingAddress { get; set; }
}
public class DtoShippingAddress
{
public int Id { get; set; }
public List<string> AddressLines { get; set; }
}
public class DtoBillingAddress
{
public int Id { get; set; }
public List<string> AddressLines { get; set; }
}
public class Initializer : DropCreateDatabaseAlways<ClientContext>
{
protected override void Seed(ClientContext context)
{
context.CustomerAccounts.Add(new UserQuery.CustomerAccount {ECommercePublished=true, Articles = new []{ new Article{IsDefault=true, NationId=1, ProductId=1}}});
}
}
public class ClientContext : DbContext
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
Database.Log = s=>Debug.WriteLine(s);
Database.SetInitializer(new Initializer());
}
public DbSet<CustomerAccount> CustomerAccounts { get; set; }
}
我需要它的实现方式,但失败了:
//The nested query is not supported. Operation1='Case' Operation2='Collect'
public void Main()
{
Mapper.Initialize(cfg =>
{
cfg.CreateMap<CustomerAccount, DtoCustomerAccount>
.ForMember(dto => dto.Address,
entity => entity.MapFrom(source =>
source.BillingAddress == null
? new Address
{
Id = source.ShippingAddress.Id,
AddressLines = new [] // or new List<string>
{
source.ShippingAddress.AddressLine1,
source.ShippingAddress.AddressLine2,
source.ShippingAddress.AddressLine3
}
}
: new Address
{
Id = source.BillingAddress.Id,
AddressLines = new [] // or new List<string>
{
source.BillingAddress.AddressLine1,
source.BillingAddress.AddressLine2,
source.BillingAddress.AddressLine3
}
}));
});
Mapper.AssertConfigurationIsValid();
var context = new ClientContext();
var result = context.CustomerAccounts.ProjectTo<DtoCustomerAccount>();//.Dump();
}
public class CustomerAccount
{
public int Id { get; set; }
public ShippingAddress ShippingAddress { get; set; }
public BillingAddress BillingAddress { get; set; }
}
public class ShippingAddress
{
public int Id { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string AddressLine3 { get; set; }
}
public class BillingAddress
{
public int Id { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string AddressLine3 { get; set; }
}
public class DtoCustomerAccount
{
public int Id { get; set; }
public DtoAddress Address { get; set; }
}
public class DtoAddress
{
public int Id { get; set; }
public List<string> AddressLines { get; set; }
}
public class Initializer : DropCreateDatabaseAlways<ClientContext>
{
protected override void Seed(ClientContext context)
{
context.CustomerAccounts.Add(new UserQuery.CustomerAccount {ECommercePublished=true, Articles = new []{ new Article{IsDefault=true, NationId=1, ProductId=1}}});
}
}
public class ClientContext : DbContext
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
Database.Log = s=>Debug.WriteLine(s);
Database.SetInitializer(new Initializer());
}
public DbSet<CustomerAccount> CustomerAccounts { get; set; }
}
从技术上讲,这不是AutoMapper的问题,因为ProjectTo
仅使用您提供的表达式。 在这种情况下,带有List<string>
的EF查询技巧不适用于条件运算符,因为BillingAddress
和ShippingAddress
是导航属性,并且EF转换程序试图使用无法与条件运算符组合的子查询。 因此,您需要找到与EF查询兼容的方式来指定所需的投影。
一种可能的方法是对每个结果地址属性使用条件运算符:
.ForMember(dto => dto.Address, entity => entity.MapFrom(source => new DtoAddress
{
Id = source.BillingAddress != null ? source.BillingAddress.Id : source.ShippingAddress.Id,
AddressLines = new List<string>
{
source.BillingAddress != null ? source.BillingAddress.AddressLine1 : source.ShippingAddress.AddressLine1,
source.BillingAddress != null ? source.BillingAddress.AddressLine2 : source.ShippingAddress.AddressLine2,
source.BillingAddress != null ? source.BillingAddress.AddressLine3 : source.ShippingAddress.AddressLine3,
}
}))
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