在不使用Automapper的情况下，我试图将DTO的列表映射到DTO的列表的每个元素中。具体地说，在此示例中，我希望API返回一个父母列表，其中每个父母都包含它的孩子列表和宠物列表。
我有一个带有以下模型的EF Core项目（该模型使用完全定义的关系），并且存在于较大的数据库中。
有一个Parent对象，其中包含许多Pet对象和许多Child对象，例如：
public class Parent
{
public int ParentId { get; set; }
public string Name { get; set; }
public List<Child> Children { get; set; }
public List<Pet> Pets { get; set; }
}
public class Child
{
public int ChildId { get; set; }
public string Name { get; set; }
public int ParentId { get; set; }
public Parent Parent { get; set; }
}
public class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
public int ParentId { get; set; }
public Parent Parent { get; set; }
}
我不使用Automapper，而是尝试在控制器中使用DTO将数据发送出去。
我已经按照以下步骤设置了DTO：
public class ParentDTO
{
public int ParentId { get; set; }
public string Name { get; set; }
//Should these be List<> or IEnumerable<>?
public IEnumerable<ChildDTO> Children { get; set; }
public IEnumerable<PetDTO> Pets { get; set; }
}
public class ChildDTO
{
public int ChildId { get; set; }
public string Name { get; set; }
}
public class PetDTO
{
public int PetId { get; set; }
public string Name { get; set; }
}
当前我的控制器如下：
// GET: api/Parents/
[HttpGet]
public IEnumerable<ParentDTO> GetParents()
{
var parents = from pa in _context.Parents
select new ParentDTO()
{
Name = pa.Name
};
return parents;
}
// GET: api/Parents/GetParentsWith
[HttpGet("[action]")]
public IEnumerable<ParentDTO> GetParentsWith()
{
var parents = from pa in _context.Parents
select new ParentDTO()
{
Name = pa.Name,
//Not sure how to correctly do this below...
Children = (from c in _context.Children.Where(c => c.ParentId == pa.ParentId)
select new ChildDTO()
{
Name = c.Name
}),
Pets = (from pe in _context.Pets.Where(pet => pet.ParentId == pa.ParentId)
select new PetDTO()
{
Name = pe.Name
})
};
return parents;
}
我的GET: api/Parents/正常工作（因为我不想创建嵌套列表），但是我如何像在{中尝试的那样，将相关的子项和宠物项添加到父DTO中{1}}？
尝试此操作会出现错误：
GET: api/Parents/GetParentsWith我也尝试过：
Microsoft.Data.SqlClient.SqlException (0x80131904): Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
....
...
这也会产生错误：
// GET: api/Parents/GetParentsWith
[HttpGet("[action]")]
public IEnumerable<ParentDTO> GetParentsWith()
{
var parents = from pa in _context.Parents
select new ParentDTO()
{
Name = pa.Name,
Children = (from c in pa.Children
select new ChildDTO()
{
Name = c.Name
}),
Pets = (from pe in pa.Pets
select new PetDTO()
{
Name = pe.Name
})
};
return parents;
}
我也尝试过：
Microsoft.Data.SqlClient.SqlException (0x80131904): Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
....
...
不会引发任何错误所以也许我在正确的轨道上，不幸的是，它只是返回空值，而我希望其中有一系列的孩子或宠物：
// GET: api/Parents/GetParentsWith
[HttpGet("[action]")]
public IEnumerable<ParentDTO> GetParentsWith()
{
var parents = from pa in _context.Parents
select new ParentDTO()
{
ParentId = pa.ParentId,
Name = pa.Name
};
foreach (ParentDTO parent in parents)
{
var children = from child in _context.Children where child.ParentId == parent.ParentId
select new ChildDTO()
{
ChildId = child.ChildId,
Name = child.Name
};
var pets = from pet in _context.Pets
where pet.ParentId == parent.ParentId
select new PetDTO()
{
PetId = pet.PetId,
Name = pet.Name
};
parent.Children = children;
parent.Pets = pets;
return parents;
}
我注意到[
{
"parentId": 1,
"name": "Ronald",
"children": null,
"pets": null
},
{
"parentId": 2,
"name": "Benjamin",
"children": null,
"pets": null
},
{
"parentId": 3,
"name": "Sally",
"children": null,
"pets": null
},
{
"parentId": 4,
"name": "Foobar",
"children": null,
"pets": null
}
]
是一个IQueryable，因此foreach中的分配没有按我预期的那样工作...我想我需要学习一些有关IQueryable，IEnumerable等的信息。
parents