C# 自动映射基于嵌套值重新映射对象

我目前正在从数据库中获取一个对象列表，并希望通过Automapper以某种方式从我的ASP.NETWebAPI返回它。从数据库中获取对象后，我的对象当前看起来像这样：

[
    {
        "id": 1,
        "dropdown": "Country",
        "value": "Germany"
    },
    {
        "id": 2,
        "dropdown": "Country",
        "value": "United States"
    },
    {
        "id": 5,
        "dropdown": "Type",
        "value": "Lead"
    },
    {
        "id": 6,
        "dropdown": "Type",
        "value": "Account"
    },
    {
        "id": 7,
        "dropdown": "Type",
        "value": "Reseller"
    },
    {
        "id": 8,
        "dropdown": "Type",
        "value": "Distributor"
    }
]

但我希望它看起来像这样：

[{
    "Countries": [{
        "id": 1,
        "value": "Germany"
      },
      {
        "id": 2,
        "value": "United States"
      }
    ]
  },
  {
    "Type": [{
        "id": 5,
        "value": "Lead"
      },
      {
        "id": 6,
        "value": "Account"
      }
    ]
  }
]

    public async Task<IEnumerable<DropdownValue>> GetDropdownValues(string[] dropdowns)
    {
        var dropdownValues = _context.DropdownValues.OrderBy(x => x.Id).ThenBy(x => x.Dropdown).AsQueryable();

        if (dropdowns.Length != 0 || dropdowns != null)
        {
            dropdownValues = dropdownValues.Where(x => dropdowns.Contains(x.Dropdown));
        }

        var dropdownValuesToReturn = await dropdownValues.ToListAsync();

        return dropdownValuesToReturn;
    }

//Your result class should actually look like this to match JSON:
class DropDownListDto
{
    public string Description {get;set;}
    //here you need an IEnumerable to store the list of Ids and values associated
    //with this drop-down.  you could create a class and declare a LIST<> of that
    //but I'll just use a dictionary instead.
    public Dictionary<int, string> DropDownValues{get;set;}
}

//Get source data
var source = await GetDropDownValues(<insert [] here>);

//transform list into IEnumerable<DropDownListDto>
var result = source
    //if we GROUP BY the Dropdown property then we'll get a distinct list of
    //of drop-downs.
    .GroupBy(x=>x.DropDown)
    //can then get the list of values and Ids from the resulting groups
    .Select(g=>new DropDownListDto
         {
              //key is the grouped by thing - drop down name..
              Description = g.Key,
              //doing a .select from the group result gives the elements
              //in that group only.  Get an anonymous type and cast that
              //to our required dictionary type
              DropDownValues = g
                .Select(x=>new{ key=x.Id, value = x.Value})
                .ToDictionary(k=>k.key, v=>v.value)
         });

当前我的CreateMap看起来像这样

CreateMap<DropdownValue, DropdownValueListDto>();

public class DropdownValueListDto
{
    public int Id { get; set; }
    public string Dropdown { get; set; }
    public string Value { get; set; }
}

我的LINQ操作如下所示：

[{
    "Countries": [{
        "id": 1,
        "value": "Germany"
      },
      {
        "id": 2,
        "value": "United States"
      }
    ]
  },
  {
    "Type": [{
        "id": 5,
        "value": "Lead"
      },
      {
        "id": 6,
        "value": "Account"
      }
    ]
  }
]

    public async Task<IEnumerable<DropdownValue>> GetDropdownValues(string[] dropdowns)
    {
        var dropdownValues = _context.DropdownValues.OrderBy(x => x.Id).ThenBy(x => x.Dropdown).AsQueryable();

        if (dropdowns.Length != 0 || dropdowns != null)
        {
            dropdownValues = dropdownValues.Where(x => dropdowns.Contains(x.Dropdown));
        }

        var dropdownValuesToReturn = await dropdownValues.ToListAsync();

        return dropdownValuesToReturn;
    }

//Your result class should actually look like this to match JSON:
class DropDownListDto
{
    public string Description {get;set;}
    //here you need an IEnumerable to store the list of Ids and values associated
    //with this drop-down.  you could create a class and declare a LIST<> of that
    //but I'll just use a dictionary instead.
    public Dictionary<int, string> DropDownValues{get;set;}
}

//Get source data
var source = await GetDropDownValues(<insert [] here>);

//transform list into IEnumerable<DropDownListDto>
var result = source
    //if we GROUP BY the Dropdown property then we'll get a distinct list of
    //of drop-downs.
    .GroupBy(x=>x.DropDown)
    //can then get the list of values and Ids from the resulting groups
    .Select(g=>new DropDownListDto
         {
              //key is the grouped by thing - drop down name..
              Description = g.Key,
              //doing a .select from the group result gives the elements
              //in that group only.  Get an anonymous type and cast that
              //to our required dictionary type
              DropDownValues = g
                .Select(x=>new{ key=x.Id, value = x.Value})
                .ToDictionary(k=>k.key, v=>v.value)
         });

公共异步任务GetDropdownValues（字符串[]下拉列表） { var dropdownValues=_context.dropdownValues.OrderBy（x=>x.Id）.ThenBy（x=>x.Dropdown.AsQueryable（）； if（dropdowns.Length！=0 | | dropdowns！=null） { dropdownValues=dropdownValues.Where（x=>dropdowns.Contains（x.Dropdown））； } var dropdownValuesToReturn=等待dropdownValues.ToListSync（）； 返回dropdownValuesToReturn； } 如果有人能帮我做到这一点，那就太好了

---

提前感谢

根据您的编辑，我想您必须这样做：

[{
    "Countries": [{
        "id": 1,
        "value": "Germany"
      },
      {
        "id": 2,
        "value": "United States"
      }
    ]
  },
  {
    "Type": [{
        "id": 5,
        "value": "Lead"
      },
      {
        "id": 6,
        "value": "Account"
      }
    ]
  }
]

    public async Task<IEnumerable<DropdownValue>> GetDropdownValues(string[] dropdowns)
    {
        var dropdownValues = _context.DropdownValues.OrderBy(x => x.Id).ThenBy(x => x.Dropdown).AsQueryable();

        if (dropdowns.Length != 0 || dropdowns != null)
        {
            dropdownValues = dropdownValues.Where(x => dropdowns.Contains(x.Dropdown));
        }

        var dropdownValuesToReturn = await dropdownValues.ToListAsync();

        return dropdownValuesToReturn;
    }

//Your result class should actually look like this to match JSON:
class DropDownListDto
{
    public string Description {get;set;}
    //here you need an IEnumerable to store the list of Ids and values associated
    //with this drop-down.  you could create a class and declare a LIST<> of that
    //but I'll just use a dictionary instead.
    public Dictionary<int, string> DropDownValues{get;set;}
}

//Get source data
var source = await GetDropDownValues(<insert [] here>);

//transform list into IEnumerable<DropDownListDto>
var result = source
    //if we GROUP BY the Dropdown property then we'll get a distinct list of
    //of drop-downs.
    .GroupBy(x=>x.DropDown)
    //can then get the list of values and Ids from the resulting groups
    .Select(g=>new DropDownListDto
         {
              //key is the grouped by thing - drop down name..
              Description = g.Key,
              //doing a .select from the group result gives the elements
              //in that group only.  Get an anonymous type and cast that
              //to our required dictionary type
              DropDownValues = g
                .Select(x=>new{ key=x.Id, value = x.Value})
                .ToDictionary(k=>k.key, v=>v.value)
         });

//为了匹配JSON，结果类实际上应该如下所示：
类DropDownListDto
{
公共字符串说明{get；set；}
//这里需要一个IEnumerable来存储ID和关联值的列表
//使用此下拉列表。您可以创建一个类并声明该类的列表
//但我会用字典来代替。
公共字典下拉值{get；set；}
}
//获取源数据
var source=等待GetDropDownValues（）；
//将列表转换为IEnumerable
var结果=源
//如果我们按下拉属性分组，那么我们将得到一个不同的
//下拉列表。
.GroupBy（x=>x.下拉列表）
//然后可以从结果组中获取值和ID的列表
.选择（g=>new DropDownListDto
{
//键是按事物分组的下拉列表名称。。
描述=g.键，
//从组结果中进行选择将得到元素
//仅在该组中。获取匿名类型并强制转换该类型
//到我们所需的字典类型
下拉值=g
.Select（x=>new{key=x.Id，value=x.value}）
.ToDictionary（k=>k.key，v=>v.value）
});

---

这应该会给你一些你想要的东西-虽然我没有测试过…

这里你不想要一个简单的映射，这更像是一个转换操作。-您可以为此使用linq to对象。我在上面插入了用于linq操作的代码。如何使用LINQ to对象？显示数据外观的JSON与

DropDownValueListDto

对象不匹配。。。JSON的东西更像你期望看到的吗？是的，JSON的东西更像我期望看到的。我试图修改DropDownValueListD以匹配我希望看到它的方式，但没有成功。好的，我将一起给出答案。。。。给我一个mo…@EE-没问题。今天早上我意识到，我没有对声明

result

为新的

列表的行执行任何操作，因此我删除了它，并添加了一条注释，使得
result
变量实际上是一个
IEnumerable
。如果需要实际的
列表
类型，您可以使用
.ToList（）
来强制转换该类型，但它可能会按原样执行。