在linq C#中分组时更新同一对象中的count属性

pkwftd7m 于 2023-01-18 发布在 C#

关注(0)|答案(2)|浏览(147)

班级：

Contact{
        public int Id { get; set; }

        public string Email { get; set; }

        public string DisplayName { get; set; }
        
        public int DocCount { get; set; }

        public string DocName { get; set; }
        

}

我有一个联系人名单看起来像是

var contactList = new List<Contact>(){ 
                           new Contact(){1,"abc@abc.com","ABC",0,"testdoc1"},
                           new Contact(){1,"abc@abc.com","ABC",0,"testdoc2"},
                           new Contact(){1,"abc@abc.com","ABC",0,"testdoc3"},
                           new Contact(){2,"xyz@abc.com","XYZ",0,"testdoc1"},
                           new Contact(){2,"xyz@abc.com","XYZ",0,"testdoc2"},
                           new Contact(){2,"xyz@abc.com","XYZ",0,"testdoc3"},
                           new Contact(){3,"mop@abc.com","MOP",0,"testdoc1"},
                           new Contact(){3,"mop@abc.com","MOP",0,"testdoc2"},
}

我正在寻找的输出，我需要更新的文件计数的基础上，由用户上传的文件计数。

预期输出为：

{1,"abc@abc.com","ABC",3,"testdoc1 testdoc2 testdoc3"},
{2,"xyz@abc.com","XYZ",3,"testdoc1 testdoc2 testdoc3"},
{3,"mop@abc.com","MOP",2,"testdoc1 testdoc2"}

有什么方法可以做到这一点吗？我知道我们可以引入新类并实现它，但需要一些最小的东西

linq

来源：https://stackoverflow.com/questions/75143296/update-the-count-property-in-the-same-object-while-grouping-in-linq-c-sharp

2条答案

按热度按时间

hmae6n7t1#

我认为通过LINQ更新示例不是一个好的实践--只需创建一个新的Contact示例：

var result = contactList
    .GroupBy(c => c.Id)
    .Select(gr => new Contact
    {
        Id = gr.Key,
        Email = gr.First().Email,
        DisplayName = gr.First().DisplayName,
        DocCount = gr.Count(),
        DocName = string.Join(", ", gr.Select(c => c.DocName))
    })
    .ToList();

或者，如果您预计电子邮件/显示名称会出现差异：

var result = contactList
    .GroupBy(c => (c.Id, c.Email, c.DisplayName))
    .Select(gr => new Contact
    {
        Id = gr.Key.Id,
        Email = gr.Key.Email,
        DisplayName = gr.Key.DisplayName,
        DocCount = gr.Count(),
        DocName = string.Join(", ", gr.Select(c => c.DocName))
    })
    .ToList();

赞(0）回复(0）举报 2023-01-18

ssm49v7z2#

您可以将GroupBy()和Select()结合使用：

var newList = contactList
        .GroupBy(p => new { p.Id, p.Email, p.DisplayName} )
        .Select(p=> new Contact(p.Key.Id,
                                p.Key.Email,
                                p.Key.DisplayName,
                                p.Count(),
                                string.Join(" ",p.Select(o=>o.DocName))))
        .ToList();

赞(0）回复(0）举报 2023-01-18

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在linq C#中分组时更新同一对象中的count属性

2条答案

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