c# - Entity frame work: many to many relationship tables -


i have news entity , news based on newsid. defined new entity , group , want news based on group id. defined group news table aslo relate table together. enter image description here

in news model have :

public virtual icollection<groupnews> relatedgroupid { get; set; }

so assumed defined groupnews table values , can use in newsservice.

now lets @ newsservice : 

    expression<func<news, bool>> constraint = null;      if (user_id > 0 && project_id > 0)     {         constraint = e => (e.creatorid == user_id && e.relatedprojecttags.any(p => p.projectid == project_id));     }     else if (user_id > 0)     {         constraint = e => (e.creatorid == user_id);     }     else if (project_id > 0)     {         constraint = e => (e.relatedprojecttags.any(p => p.projectid == project_id));     }      else     {         constraint = null;     }      ienumerable<news> result_list = null;      if (constraint != null)     {         result_list = newsrepository.getmany(constraint).orderbydescending(e => e.createdon).skip(offset);     }     else     {         result_list = newsrepository.getall().orderbydescending(e => e.createdon).skip(offset);     }      if (count > 0)     {         result_list = result_list.take(count);     }      return result_list.tolist<news>(); }

}

i add line in order define constraint based on groupid.

    else if (groupid > 0)     {         constraint = e => (e.relatedgroupid.any(n => n.groupid == groupid));     }

it seems wrong , gives me error :

{"invalid object name 'dbo.groupnewsnews'."}

1.you not need groupnewsid in groupnews table. need drop column , create complex key groupid , newsid. in news entity need define property:

    public virtual icollection<group> groups      {          get;          set;      }

in default constructor entity need initialize property(need lazy load):

groups = new list<group>();

similar changes group entity.

2.in groupmap.cs need define

this.hasmany(t => t.news)     .withmany(t => t.groups)     .map(m =>         {             m.totable("groupnews");             m.mapleftkey("groupid");             m.maprightkey("newsid");         });

3.write tests newsrepository , grouprepository.


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