Lambda表达式的捧场 [英] Lambda Expression for join

问题描述

public class CourseDetail
    {
        public CourseDetail();
        public string CourseId { get; set; }
        public string CourseDescription { get; set; }
        public long CourseSer { get; set; }
    }

 public class RefUIDByCourse
    {
        public long CourseSer {  get;  set; }
        public double DeliveredDose{ get; set; }
        public double PlannedDose{ get; set; }
        public string RefUID {  get;  set; }
     }
 public class RefData
    {
       public double DailyDoseLimit {  get;  set; }
       public string RefName {  get;  set; }
       public string RefUID {  get;  set; }
       public double SessionDoseLimit {  get;  set; }
    }

public class CourseSummary  
    {    
          public long CourseSer { get; set; } 
          public double DeliveredDose{ get; set; } 
          public double PlannedDose{ get; set; } 
          Public List<RefData> lstRefData {get;set;} 
    }

其一courseSer有可以在多个RefUID RefUIDByCourse
和每RefUID会有RefData一个记录

For one courseSer there can be multiple RefUID in RefUIDByCourse and for every RefUID there will be one record in RefData

我有CourseDetail，RefUIDByCourse和RefData
名单现在对于courseser在coursedetail存在我要创建CourseSummary列表。

的有一件事情我可以做的是循环做coursedetail并使用取各自refdata LINQ查询并创建coursesummary的对象，并在列表中添加它。的

的 ，但有什么办法一个LINQ做查询，而不是通过的

but is there any way to do it by one linq query instead of doing loop through

推荐答案

对于加入的拉姆达做循环是参与了一点 - 这里的一个简单的例子：

The lambda for a Join is a bit involved - here's a simple example:

List<Person> People = new List<Person>();
List<PersonType> PeopleTypes = new List<PersonType>();

var joined = People.Join(PeopleTypes, PeopleKey => PeopleKey.PersonType, PeopleTypesKey => PeopleTypesKey.TypeID, (Person, PersoneType) => new { Name = Person.Name, TypeID = PersoneType.TypeID });

我通常会发现查询语法很多比lambda表达式加盟

I usually find the query syntax a lot more readable than lambdas for joining

        var joined2 = from p in People
                      join pType in PeopleTypes
                      on p.PersonType equals pType.TypeID
                      where p.Name.StartsWith("whatever")
                      select new { Name = p.Name, TypeID = pType.TypeID };

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