c# - Linq 查询 Group By 和 contains

Question

我有一个字符串列表，它是货币代码。

var currencyCode = new List<string>() { "USD", "SGD", "KWD", "BHD", "LYD" };

我还有另一个复杂的对象。

 var rate = new List<Rate>()
 {
        new Rate() { CurrencyName = "USD (SMALL)",CurrencyCode = "USD SMALL",BranchName="Branch1"},
        new Rate() { CurrencyName = "SGD BIG",CurrencyCode = "SGD BIG",BranchName="Branch1"},
        new Rate() { CurrencyName = "KUWAIT DINAR",CurrencyCode = "KWD",BranchName="Branch1"},
        new Rate() { CurrencyName = "USD BIG (100,50)",CurrencyCode = "USD BIG",BranchName="Branch1"},
        new Rate() { CurrencyName = "USD MEDIUM (10,20)",CurrencyCode = "USD MEDIUM",BranchName="Branch1"},
  };

我将在下面的列表中找到匹配的货币:

var matchedCurrency = from c in rate
                      where currency.Any(w => c.CurrencyCode.Contains(w))
                      select c;

我想要的是匹配的货币列表应该按货币代码分组。

我尝试了以下方法，但没有成功。

 var Grp = rate.GroupBy(item => currency.Any(w => item.CurrencyCode.Contains(w)))
          .Select(group => new
          {
              group.Key,
              DataList = group.ToList()
           });

我不明白我实际上失踪了。我通过各种方式尝试过。

我知道我可以遍历rate并插入另一个对象。但这看起来不太好，我想通过使用 Linq 来做到这一点。但我没能达到这个目的。

输出将与此对象一起显示:

public class CurrencyMap
{
    public string Code { get; set; }

    public List<Currency> currency { get; set; }
}
public class Currency
{
    public string CurrencyName { get; set; }
    public string CurrencyCode { get; set; }
    public string BranchName { get; set; }
}
enter code here

编辑:

我一开始错过了这些事情，但如果在费率中找不到匹配的代码，我也需要有空列表。

在费率中没有“BHD”、“LYD”的匹配列表。但我还需要带有代码“BHD”、“LYD”的空列表

Answer 1

首先选择匹配的货币代码，然后按所选代码进行分组。

var groupedRates = rate
    .Select(r => new
    {
        rate = r,
        code = currencyCode.FirstOrDefault(c => r.CurrencyCode.Contains(c))
    })
    .GroupBy(x => x.code, x => x.rate); //maybe you don't want to throw away the resolved code like I do in the element selector...

编辑:我想我有点专注于分组方面。由于您想要包含所有货币代码并提到特定的输出结构，因此无需考虑分组，只需选择结果即可:

var groupedRatesList = currencyCode
    .Select(c => new CurrencyMap
    {
         Code = c,
         currency = rate
            .Where(x => x.CurrencyCode.Contains(c))
            .Select(x => new Currency
            {
                BranchName = x.BranchName,
                CurrencyCode = x.CurrencyCode, // or maybe you want to insert c here?
                CurrencyName = x.CurrencyName
            })
            .ToList()
     })
     .ToList();