如何使用LINQ在C#中重構物件？

我有一個資料集如下：

[
    {
        "Id": 1,
        "Country": "Uruguay",
        "Name": "Foo",
        "Status": "Completed",
    },
    {
        "Id": 2,
        "Country": "Uruguay",
        "Name": "Foo",
        "Status": "Completed",
    },
    {
        "Id": 3,
        "Country": "Germany",
        "Name": "Foo",
        "Status": "Completed",
    },
]

我想按 Country 對其進行轉換和排序，使其如下所示：

[
    {
        "Country": "Uruguay",
        "Details": [
         {
            "Id": 1,
            "Name": "Foo",
            "Status": "Completed",
         },
         {
            "Id": 2,
            "Name": "Foo",
            "Status": "Completed",
         },
        ],
    },
    {
        "Country": "Germany",
        "Details": [
         {
            "Id": 3,
            "Name": "Foo",
            "Status": "Completed",
         },
        ],
    },
],

這些是 C# 中的類：

public class Countries {
    public int Id { get; set; }
    public string Country { get; set; }
    public string Name { get; set; }
    public string Status { get; set; }
}

public class Details {
    public int Id { get; set; }
    public string Name { get; set; }
    public string Status { get; set; }
}

public class CountryList {
    public string Country { get; set; }
    public List<Details> Details { get; set; }
}

我嘗試過的一些方法如下：

var foo = countries
    .GroupBy(x => new Details { Id = x.Id, Name = x.Name, Status = x.Status })
    .Select( y => new CountryList 
     {
         // Country = y.Key. 
     }

var foo = countries
    .GroupBy(x => x.Country)
    .Select( y => new CountryList 
     {
         // Country = y.Key.
         Details = y.GroupBy(a => new Details 
         { 
            Id = a.Id, 
            Name = a.Name, 
            Status = a.Status  
         }).ToList() 
     }

我無法弄清楚如何使用 LINQ 來解決這個問題。我過去做過一些 GroupBy 操作，但我無法解決這個問題。如何將我的資料集轉換為所需的結果？

uj5u.com熱心網友回復：

您不需要第二個 GroupBy

var foo = countries
    .GroupBy(x => x.Country)
    .Select(y => new CountryList 
     {
         Country = y.Key,
         Details = y.Select(a => new Details 
         { 
            Id = a.Id, 
            Name = a.Name, 
            Status = a.Status  
         }).ToList() 
     };

uj5u.com熱心網友回復：

您可以利用.GroupBy()允許您定義 a resultSelector來創建您CountryList的 s 并填充它們的多載Details：

var countries = new List<Countries>
{
    new() { Id = 1, Country = "Uruguay", Name = "Foo", Status = "Completed" },
    new() { Id = 2, Country = "Uruguay", Name = "Foo", Status = "Completed" },
    new() { Id = 3, Country = "Germany", Name = "Foo", Status = "Completed" },
};

List<CountryList> countryList = countries
    .GroupBy(
        c => c.Country,
        ( country, matches ) => new CountryList()
            {
                Country = country,
                Details = matches.Select(match => new Details 
                    { 
                        Id = match.Id, 
                        Name = match.Name, 
                        Status = match.Status 
                    }).ToList()
            })
    .ToList();

,( country, matches ) => new CountryList() { ... }作為resultSelector.

示例小提琴在這里。

uj5u.com熱心網友回復：

嘗試這個

var orig = JsonConvert.DeserializeObject<List<Countries>>(json); 

List<CountryList> countries = orig.GroupBy(o => o.Country)
.Select(x => new CountryList {
Country = x.Key,
Details = x.Select(o => new Details {Id=o.Id,Name=o.Name,Status=o.Status} ).ToList()
}).ToList();

 

標籤：json 林克 通过...分组 c#-3.0

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