c# - Entity Framework : many to many relationship , Insert and update -


i have news entity , news based on newsid. defined new entity , group , want news based on group id. tried handle (many many) relationships using this articleby using code first approach.

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so in context added :

 public class groupnews : dbcontext     {          public dbset<group> group { get; set; }         public dbset<news> news { get; set; }          public groupnews()             : base("mydb")         {         }          public int newsid { get; set; }     }  this.hasmany(t => t.news)     .withmany(t => t.groups)     .map(m =>         {             m.totable("groupnews");             m.mapleftkey("groupid");             m.maprightkey("newsid");         });

now can news based on groupid using approach. problem in insertign new news , updating.for need save newsid , groupid in groupnews table. doing . in news model defined :

    public virtual icollection<group> relatedgroups { get; set; }      public news()     {         relatedgroups = new list<group>();     }

and same group :

    public virtual icollection<news> relatednews { get; set; }     public group()     {         relatednews = new list<news>();      }

in news controller add :

            group group = new group();             group.relatednews.add(news);

enter image description here

but nothing updated , newsid not adding groupnews table .

you should not define groupnews separately. meaning, should not have groupnews class defined in project. have crud operations using independent associations (a list of news in group class , list of group in news class). here's classes should like: 

public class group {     ...     public group()     {          this.news = new list<news>();     }      public virtual icollection<news> news {get;set;} }  public class news {     ...     public news()     {          this.group = new list<group>();     }     public virtual icollection<group> groups {get;set;} }  public class mycontext : dbcontext {     public dbset<group> groups { get; set; }     public dbset<news> news { get; set; } }

then can use mygroup.news.add(mynewsitem) or mynews.groups.add(mygroup). entity framework handle insertion automatically. notice should use virtual keyword if want enable lazy loading associations.


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