Question

     List<Person> persons = null;
                persons = new List<Person>();
                persons.Add(new Person
                {
                    Id = 1,
                    FirstName = "Chris",
                    LastName = "Cummings",
                    phn = 111223333,
                    comment="test"
                }); 
                persons.Add(new Person
                {
                    Id = 2,
                    FirstName = "Chris",
                    LastName = "Cummings",
                    phn = 987654321,
                    comment=""
                });
                persons.Add(new Person
                {
                    Id = 3,
                    FirstName = "John",
                    LastName = "Steinbeck",
                    phn = 111223333,
                    comment = "dfdf"
                }); 
persons.Add(new Person
            {
                Id = 4,
                FirstName = "fgg",
                LastName = "hgh",
                phn = 545,
                comment = ""
            });

从上面的列表中我想显示以下数据

如果姓氏和姓氏与任何人必须包含评论的人匹配，否则将删除没有评论的其他人

    Id = 1,
                    FirstName = "Chris",
                    LastName = "Cummings",
                    phn = 111223333,
                    comment="test"
    Id = 3,
                    FirstName = "John",
                    LastName = "Steinbeck",
                    phn = 111223333,
                    comment = "dfdf"
Id = 4,
                    FirstName = "fgg",
                    LastName = "hgh",
                    phn = 545,
                    comment = ""

Answer 1

您可以使用GroupBy并使用SelectMany功能

过滤结果

var result = 
    persons.GroupBy(p => new { p.FirstName, p.LastName })
           .SelectMany(g => g.Where(p => string.IsNullOrEmpty(p.Comment) == false));

如果您想要保留没有匹配人并且评论为空的人，您可以添加条件group.Count() == 1

var result = 
    persons.GroupBy(p => new { p.FirstName, p.LastName })
           .SelectMany(g => 
                      {
                          var isSingle = g.Count() == 1;
                          return g.Where(p => isSingle || !string.IsNullOrEmpty(p.Comment))
                      });

Answer 2

//Union the persons and use the comparer class

var result =   persons.Union(persons, new PersonComparer()).Where(e=> !string.IsNullOrEmpty( e.comment));
//Use the below comparer class

public class PersonComparer : IEqualityComparer<Person>
{

    public bool Equals(Person x, Person y)
    {
        return x.FirstName == y.FirstName && x.LastName == y.LastName;
    }

    public int GetHashCode(Person obj)
    {
        return obj.FirstName.GetHashCode() + obj.LastName.GetHashCode();
    }
}

根据c＃中列表集合中的单个值合并两个列表项

2 个答案: