List<Dictionary<string，object>>按键和值分组

Question

我有一个类似于以下内容的List<Dictionary<string, object>>：

var myList =
            new List<Dictionary<string, object>>
            {
                new Dictionary<string, object>
                {
                    { "Name", "Bob" },
                    { "Certification", "Certification A" },
                    { "Date", "10/1/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Bob" },
                    { "Certification", "Certification A" },
                    { "Date", "01/01/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Bob" },
                    { "Certification", "Certification B" },
                    { "Date", "10/5/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Joe" },
                    { "Certification", "Certification A" },
                    { "Date", "10/5/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Joe" },
                    { "Certification", "Certification B" },
                    { "Date", "10/5/2022" }
                },
                new Dictionary<string, object>
                {
                    { "Name", "Joe" },
                    { "Certification", "Certification B" },
                    { "Date", "01/01/2022" }
                }
            };

我需要按Name和Certification进行分组，这样我就可以得到以下结果：

{
    new Dictionary<string, object>
    {
        { "Name", "Bob" },
        { "Certification", "Certification A" },
        { "Date", "10/1/2022" }
    },
    new Dictionary<string, object>
    {
        { "Name", "Bob" },
        { "Certification", "Certification B" },
        { "Date", "10/5/2022" }
    },
    new Dictionary<string, object>
    {
        { "Name", "Joe" },
        { "Certification", "Certification A" },
        { "Date", "10/5/2022" }
    },
    new Dictionary<string, object>
    {
        { "Name", "Joe" },
        { "Certification", "Certification B" },
        { "Date", "10/5/2022" }
    }
};

我完全不知道如何达到这个结果，所以任何的指导都会很感激。

Answer 1

您可以使用它们生成的相等成员来利用值元组：

var result = myList.GroupBy(d => (Name: d["Name"], Certification: d["Certification"]))
    .Select(g => g.First()) // apply ordering if needed
    .ToList();

或者匿名类型也是如此：

var result = myList.GroupBy(d => new { Name = d["Name"], Certification = d["Certification"] })
    .Select(g => g.First()) // apply ordering if needed
    .ToList();

请注意，这将要求所有字典都有所有成员和所有值，以正确实现Equals和GetHashcode。

还要注意，您可以将字典键入为Dictionary<string, string>。