C# 列表到没有 Foreach 的字典 [错误]

Question

我有这门课

class Person
{
    public string idCard { get; set; }
    public string name { get; set; }
    public DateTime birthDate { get; set; }
}

和对象列表

List<Person> list = new List<Person>(){
    new Person(){name="John",idCard="123",birthDate=new DateTime(1990,11,13)},
    new Person(){name="Paul",idCard="321",birthDate=new DateTime(1988,5,16)},
    new Person(){name="Clara",idCard="213",birthDate=new DateTime(1993,7,21)}
};

当我想在没有 foreach 的情况下将该列表转换为字典时，其中对象的属性之一是键(我一直在网上搜索以做到这一点)

Dictionary<string, Person> personDict = new Dictionary<string,Person>();
personDict = list.GroupBy(x=>x.idCard).ToDictionary<string, Person>(x => x.Key,x=>x);

还有一些错误

Error 1 Instance argument: cannot convert from 'System.Collections.Generic.IEnumerable>' to 'System.Collections.Generic.IEnumerable' G:\SHUBA\Learning\Experiments\TestProgram\TestProgram\Program.cs 25 26 TestProgram Error 4 Argument 3: cannot convert from 'lambda expression' to 'System.Collections.Generic.IEqualityComparer' G:\SHUBA\Learning\Experiments\TestProgram\TestProgram\Program.cs 25 95 TestProgram Error 3 Argument 2: cannot convert from 'lambda expression' to 'System.Func' G:\SHUBA\Learning\Experiments\TestProgram\TestProgram\Program.cs 25 83 TestProgram Error 2 'System.Collections.Generic.IEnumerable>' does not contain a definition for 'ToDictionary' and the best extension method overload 'System.Linq.Enumerable.ToDictionary(System.Collections.Generic.IEnumerable, System.Func, System.Collections.Generic.IEqualityComparer)' has some invalid arguments G:\SHUBA\Learning\Experiments\TestProgram\TestProgram\Program.cs 25 26 TestProgram

有人知道解决办法吗？

我想我是对的。

Answer 1

这应该给你一个字典，其中键是 idCard，值是 Person 对象。

Dictionary<string, Person> personDict = list.ToDictionary(x => x.idCard, y => y);

由于我们要将IdCard 值作为字典键，ToDictionary如果您的列表中有多个具有相同 idCard 值的项目，方法调用将抛出一个 ArgumentException。