在使用anonymouse对象进行分组时，如何忽略linq groupby中的case [英] How do I ignore case in linq groupby when grouping using an anonymouse object

问题描述

我有一个查询，我希望在GroupBy基于TeamID和ActivityName的地方运行。 TeamID是一个i​​nt，ActivityName是一个字符串。我想执行GroupBy查询，其中GroupBy中的键是（TeamID，ActivityName），在ActivityName中忽略该大小写。下面的代码返回4组，因为活动根据内容或案例都是不同的，我希望通过忽略大小写为2。我已经尝试将StringComparer.InvariantCultureIgnoreCase添加到查询中但是我得到一个编译错误，指出方法的类型参数'System.Linq.Enumerable.GroupBy< tsource，tkey，tresult>（System.Collections.Generic.IEnumerable< tsource>， System.Func< tsource，tkey>，System.Func< tkey，system.collections.generic.ienumerable>< tsource>，TResult>'无法从用法中推断出来。请尝试明确指定类型参数。我也尝试过在查询中使用ToUpper（）但没有成功。

我无法弄清楚应该怎么做，任何帮助都将不胜感激。



我尝试过：

I have a query that I want to run where I GroupBy based on TeamID and ActivityName. The TeamID is an int and the ActivityName is a string. I want to perform a GroupBy query where the key in the GroupBy is (TeamID, ActivityName) with the case being ignored in the ActivityName. The code below returns 4 groups as the the activities are all different based on content or case, I want there to be 2 by ignoring the case. I have tried adding StringComparer.InvariantCultureIgnoreCase to the query but I get a compilation error stating "The type arguments for method 'System.Linq.Enumerable.GroupBy<tsource,tkey,tresult>(System.Collections.Generic.IEnumerable<tsource>, System.Func<tsource,tkey>, System.Func<tkey,system.collections.generic.ienumerable><tsource>,TResult>' cannot be inferred from the usage. Try specifying the type arguments explicitly." I have also tried using ToUpper() in the query but with no success.
I can't figure out how this should be done, any help would be appreciated.

What I have tried:

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            PerformQuery();
        }

        public void PerformQuery()
        {
            List<team> teams = new List<team>();
            teams.Add(new Team { TeamId = 1, ActivityName = "Football" });
            teams.Add(new Team { TeamId = 1, ActivityName = "football" });
            teams.Add(new Team { TeamId = 2, ActivityName = "Rugby" });
            teams.Add(new Team { TeamId = 2, ActivityName = "rugby" });

            var activities = teams
                .GroupBy(e => new { e.TeamId, e.ActivityName });
        }
    }

    public class Team 
    {
        public int TeamId { get; set; }
        public string ActivityName { get; set; }
    } 

推荐答案

尝试：

Try:

var activities = teams.GroupBy(e => new { e.TeamId, e.ActivityName.ToLower() });

：doh： - 我需要更多的咖啡...

试试这个：

:doh: - I need more coffee...
Try this:

public class Team
    {
    public int TeamId { get; set; }
    public string ActivityName { get; set; }
    public string ActivityNameLower { get { return ActivityName.ToLower(); } }
    }

然后：

And then:

var activities = teams.GroupBy(e => new { e.TeamId, e.ActivityNameLower });

检查这个

check this

var activities = teams.GroupBy(e => new { TeamId = e.TeamId, ActivityName = e.ActivityName.ToLower() }).ToList();
foreach (var item in activities)
{
    var key = item.Key;
    var items = item.ToList();

}

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