使用Web Api和EF中的Linq访问具有导航属性的实体

Question

Hi I am trying to write a linq query in web api using etity framework. I have two entities

MainProj                            task_list
p_id                                t_id
p_name                              p_id
---------                           t_name
navigation properties            -------------------
task_list                         navigation properties 
                                  mainProj 

MainProj has 1 to many relation with task_list I am using following linq query

var list=( from z in MainProj 
select new pList
{
       proj_name=z.p_name
       proj_id=z.p_id
       newtasklist = new List<newtasklist>
         {
             new newtasklist {
             task_list=z.task_list.(** cant access the properties from task_list here)
    }}
  });

classes are

    public class pList
   {
       public int p_id { get; set; }
       public string p_name { get; set; }
       public IEnumerable<newtasklist> newtasklist { get; set; }

  }

   public class newtasklist
  {
       public int t_id { get; set; }
       public string t_name { get; set; }
        public int p_id { get; set; }
       public pList pList {get; set;}
   }

Please let me know how i can access task_list properties at this line in linq query

 task_list=c.task_list.(** cant access the properties from task_list here)

Answer 1

As you said there is one to many relation in Mainproj and task_list you can do something like following.

Here is a list of Mainproj

List<MainProj> mProjects = new List<MainProj>
{
    new MainProj
    {
        p_id = 1, taskList =new List<task_list> {
                    new task_list{ p_id=1, t_id = 1, t_name="Dev"},
                    new task_list{ p_id=1, t_id = 2, t_name="QA"},
                }, name="Proj1"
    },
    new MainProj
    {
        p_id = 2, taskList =new List<task_list> {
                    new task_list{ p_id=2, t_id = 1, t_name="RA"},
                    new task_list{ p_id=2, t_id = 2, t_name="DEV"},
                },name="Proj2"
     }
};

And following is the LINQ

  var lst = (from p in mProjects
             select new pList
             {
                 p_id = p.p_id,
                 p_name = p.name,
                 newtasklist = p.taskList.Select(x => new newtasklist { p_id = x.p_id, t_id = x.t_id, t_name = x.t_name })
             });

here is the Quick watch result