Asp.net How do i delete objects with One To Many using entity framework

Question

I have the following tables team and player where their are many players per team based on teamId being a guid. As you can see the first row in the team table with guid of empty i no its just a test has two records based on teamID in the players table

My Main question using entity framework how would i delete the team and the player in one go with entity framework

As you can see the frist record

So in my team grid I was just doing the following but as you see this is only grabbing the team object. Obv I could just hit out at the players object first and delete them first.

        if (e.CommandName == "Delete")
        {

            GridDataItem item = e.Item as GridDataItem;
            Guid strId = new Guid(item.GetDataKeyValue("id").ToString());
             team  _team= _dal.GetTeamByTeamId (strId);


            _dal.SoccerEntities.teams.DeleteObject(team);


        }

This is my GetTeamByTeamId function

    public team GetTeamByTeamId(Guid  teamId)
         {
        try
        {
            if (teamId == Guid.Empty)
            {
                team _team = new team();

                return _team;
            }
            else
            {
                var q = SoccerEntities.teams.Where(p => p.id == teamId);

                if (q == null)
                    throw new EntityContextException(string.Format("A team could not be found {0}!", teamId));
                else
                    return q.ToList()[0];
            }
        }
        catch (Exception ex)
        {
            throw new EntityContextException("GetTeamByTeamId failed.", ex);
        }




    }

This is asp.net by the way

Edits

I tried rankins suggesiton but have a an error on compile

Error 36 'soccerCmsDal.team' does not contain a definition for 'players' and no extension method 'players' accepting a first argument of type 'soccerCmsDal.team' could be found (are you missing a using directive or an assembly reference?) C:\new code\UniteCms\UniteCms\UniteCms\BackDoor\teams\default.aspx.cs 38 54 UniteCms

My attempt to add a foreign key

Ok now I have the foreign key setup its not working its giving me a null error

 {
            GridDataItem item = e.Item as GridDataItem;
            Guid strId = new Guid(item.GetDataKeyValue("id").ToString());
            team _team = _dal.SoccerEntities.teams.FirstOrDefault(p => p.id == strId);
            if (_team != null)
            {
                foreach (player _player in _team.players)
                {
                    _dal.SoccerEntities.players.DeleteObject(_player);
                }
                _dal.SoccerEntities.teams.DeleteObject(_team);
            }
            _dal.SoccerEntities.SaveChanges();


        }

Have you tried enabling cascading delete? (I thought this was enabled by default) — Stefan
– Stefan, Commented Nov 10, 2015 at 13:15
If the selected _team from @Rakin's answer contains the player you can also loop the collection and delete them one by one. Don't use foreach though because that might throw an exception stating that the collection has changed. (there must be something like: _team.players) — Stefan
– Stefan, Commented Nov 10, 2015 at 13:52

Rakin · Accepted Answer · 2015-11-10 14:23:56Z

1

  GridDataItem item = e.Item as GridDataItem;
            Guid strId = new Guid(item.GetDataKeyValue("id").ToString());
            team _team = _dal.SoccerEntities.teams.FirstOrDefault(p => p.id == strId);
            if (_team != null)
            {

                 if( _team.players!= null &&  _team.players.Count>0)
                 { var _palayers = _team.players.ToList();
                    foreach (player _player in _palayers )
                    {
                        _dal.SoccerEntities.players.DeleteObject(_player);
                    }
                 }
                _dal.SoccerEntities.teams.DeleteObject(_team);
            }
            _dal.SoccerEntities.SaveChanges();

edited Nov 10, 2015 at 14:23

answered Nov 10, 2015 at 13:21

Rakin

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9 Comments

dotnetdevcsharp Over a year ago

please explain how doing a for each is effiennt what if 100 records would it be quick

dotnetdevcsharp Over a year ago

I also have an error says Error 36 'soccerCmsDal.team' does not contain a definition for 'players' and no extension method 'players' accepting a first argument of type 'soccerCmsDal.team' could be found (are you missing a using directive or an assembly reference?) C:\new code\UniteCms\UniteCms\UniteCms\BackDoor\teams\default.aspx.cs 38 54 UniteCms

Rakin Over a year ago

did you set foreign key for column teamid ?

dotnetdevcsharp Over a year ago

i tried to but it sayed that i couldnt cause teamId was not unqiue but in my case teamId would be the same ??

dotnetdevcsharp Over a year ago

can you explain the foreign key i screenshoted how i was doing it in case i did it wrong

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