django-queryset差异-没有像我预期的那样工作

恐怕又是一个新手问题。我有这张有三张清单的表格。目标是更改其中两个列表的查询集（请参见视图中的代码）

form.py

class AddGameForm(forms.ModelForm):
    won_lag = forms.ChoiceField(choices=[('1','Home') , ('2', 'Away') ], )
    home_team = forms.ModelChoiceField(queryset=Player.objects.all(),required=True )
    away_team = forms.ModelChoiceField(queryset=Player.objects.all(), required=True )

    class Meta:
        model = Game
        fields = ()

def game_add(request, match_id):
    # used to create a new Game

    """ return http response page for creating a new Game """

    # Adding a new Game so just make a new one
    game = Game()

    # Get the match specified in the Querystring because we will need it to figure out     who the home team
    # and away team are.
    try:
        match = Match.objects.get(id=match_id)
    except Match.DoesNotExist:
        # we have no object!  do something
        #todo: redirect to list match page?
    pass

    # get form
    form = AddGameForm(request.POST or None, instance=game)

    # Change the Queryset for Home and Away team to show only players that are on the team
    #  AND have not already played in a game so we need to get the "DIFFERENCE" between all
    #  team members and any players that have already played in the match
    home_players = Player.objects.filter(team=match.home_team)            # All Home Team members
    away_players = Player.objects.filter(team=match.away_team)            # All Away Team members
    already_played_in_match_players = Game.objects.filter(match=match)    # This is both home and away players
                                                                      # that have played in a Game on this match

    form.fields['home_team'].queryset = home_players.exclude(pk__in=already_played_in_match_players)
    form.fields['away_team'].queryset = away_players.exclude(pk__in=already_played_in_match_players)
...

view.py

class AddGameForm(forms.ModelForm):
    won_lag = forms.ChoiceField(choices=[('1','Home') , ('2', 'Away') ], )
    home_team = forms.ModelChoiceField(queryset=Player.objects.all(),required=True )
    away_team = forms.ModelChoiceField(queryset=Player.objects.all(), required=True )

    class Meta:
        model = Game
        fields = ()

def game_add(request, match_id):
    # used to create a new Game

    """ return http response page for creating a new Game """

    # Adding a new Game so just make a new one
    game = Game()

    # Get the match specified in the Querystring because we will need it to figure out     who the home team
    # and away team are.
    try:
        match = Match.objects.get(id=match_id)
    except Match.DoesNotExist:
        # we have no object!  do something
        #todo: redirect to list match page?
    pass

    # get form
    form = AddGameForm(request.POST or None, instance=game)

    # Change the Queryset for Home and Away team to show only players that are on the team
    #  AND have not already played in a game so we need to get the "DIFFERENCE" between all
    #  team members and any players that have already played in the match
    home_players = Player.objects.filter(team=match.home_team)            # All Home Team members
    away_players = Player.objects.filter(team=match.away_team)            # All Away Team members
    already_played_in_match_players = Game.objects.filter(match=match)    # This is both home and away players
                                                                      # that have played in a Game on this match

    form.fields['home_team'].queryset = home_players.exclude(pk__in=already_played_in_match_players)
    form.fields['away_team'].queryset = away_players.exclude(pk__in=already_played_in_match_players)
...

在我的数据库中，我有以下内容：

Team 1
   Player 1
   Player 2
Team 2
   Player 3

Match 1
   no games

Player.objects.filter(player1__in=inner_query)  

...

inner_query = Game.objects.filter(match=match)    # All games in this match

# Now use reverse relation to get the Player1 union Player2 to get all players who have played in this match so far
already_played_players = Player.objects.filter(player1__in=inner_query) | Player.objects.filter(player2__in=inner_query)

...

因此，当我打开表单时，正如预期的那样，主队列表显示球员1、球员2，客队列表显示球员3

所以我选择玩家1和玩家3，然后保存游戏。 现在DB有以下数据

Team 1
   Player 1
   Player 2
Team 2
   Player 3

Match 1
   Game 1 between Player1 and Player3

我决定添加另一个游戏，所以我打开GameAddForm，希望主队列表只显示玩家2，客队列表不显示玩家

然而，在现实中，发生的事情是主队名单按预期行事，但客队名单仍然显示球员3

我完全搞不懂为什么它对主队有效而对客队无效

有什么建议吗

---

提前感谢您提供的任何指导。

好的，我想好了。基本上，问题出在以下几行：

already_played_in_match_players = Game.objects.filter(match=match)

它返回的查询集为游戏，而不是玩家

因为我想得到玩家，所以我必须从Player.object开始。这意味着我必须在游戏中提问→ 玩家1和游戏→ Player2关系向后。以下是医生们对此的看法：

Lookups that span relationships

To span a relationship, just use the field name of related fields across models, separated by double underscores, until you get to the field you want

...

To refer to a “reverse” relationship, just use the lowercase name of the model.

为了清楚起见，我把它分成了几个步骤

inner_query = Game.objects.filter(match=match)  # Gets all games in this match

然后我使用了以下方法：

Team 1
   Player 1
   Player 2
Team 2
   Player 3

Match 1
   no games

Player.objects.filter(player1__in=inner_query)  

...

inner_query = Game.objects.filter(match=match)    # All games in this match

# Now use reverse relation to get the Player1 union Player2 to get all players who have played in this match so far
already_played_players = Player.objects.filter(player1__in=inner_query) | Player.objects.filter(player2__in=inner_query)

...

本质上就是说，在innerquery查询集中的任何游戏对象中，获取player1 foreignkey引用的所有玩家对象

接下来，我使用|（管道）为player1和player2合并查询集 因此，它产生了这一行：

already_played_players = Player.objects.filter(player1__in=inner_query) | Player.objects.filter(player2__in=inner_query)

这给了我一份已经参加过比赛的所有球员的名单

变更摘要

我将违规行更改为以下内容：

Team 1
   Player 1
   Player 2
Team 2
   Player 3

Match 1
   no games

Player.objects.filter(player1__in=inner_query)  

...

inner_query = Game.objects.filter(match=match)    # All games in this match

# Now use reverse relation to get the Player1 union Player2 to get all players who have played in this match so far
already_played_players = Player.objects.filter(player1__in=inner_query) | Player.objects.filter(player2__in=inner_query)

...