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python - 限制/限制在python django（梦幻体育网站）中可以选择model.foreignkey选项的次数

问题描述

在此处输入图片描述我正在制作一个梦幻体育网站。django 开箱即用的用户等于团队所有者。在我的 blog/models.py 文件中，我创建了一个类Player（又名 NBA 球员），其外键字段player_owner指向User：

# blog/models.py
class Player(models.Model):
    player_full = models.CharField(max_length=50)
    player_owner = models.ForeignKey(User, blank=True, null=True, on_delete=models.SET_NULL)
    image = models.ImageField(default='default_player.jpg', upload_to='player_pics')
    player_unit_value = models.PositiveSmallIntegerField(default=1, validators=[MinValueValidator(1),
                                                                            MaxValueValidator(1)])

如您所见，我在 Player 类上还有一个字段，称为player_unit_value永久设置为 1。我认为，这将与我的问题有关。我设置了很多网站：自由球员页面、团队仪表板、球员资料、财务等都建立了表单验证，以确保球员被授权登录User（又名球队所有者） “签署”和“放弃” .

# blog/views.py
class PlayersUpdateView(LoginRequiredMixin, UpdateView, Player):
    model = Player
    fields = []
    template_name = 'blog/player_form.html'  # <app>/<model>_<viewtype>.html
    context_object_name = 'guys'

    def form_valid(self, form):
        form.instance.player_owner = self.request.user
        return super().form_valid(form)

因此，当您在我的网站上单击“添加播放器”时，该播放器的player_owner字段会从“无”更新为User. 而“Drop Player”按钮则相反。

所以这是我的问题：如何创建一个逻辑来限制User（又名所有者）可以选择为player_owner15 的次数？理想情况下，我希望有某种形式的验证——当由一个User已经有 15 名球员的人发起时——显示一个无效的警告，上面写着“对不起，你的名单上已经有最大数量的球员了”

这是另一个可能有用的部分：我在我的 Users/models.py Profile 类上创建了一个字段，名为players_owned：

# users/models.py
class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    image = models.ImageField(default='default.jpg', upload_to='profile_pics')
    players_owned = models.PositiveSmallIntegerField(default=0,
                                                 validators=[MinValueValidator(0),
                                                             MaxValueValidator(15)]
                                                 )

players_owned我怀疑每次将 aPlayer添加到用户的团队时（也就是每次 Player.player_owner 字段从 None 更新为 a （aka Owner）时，可能有一种方法可以将用户字段 += 1。User但是这两个类都在不同的模型文件。

我是 python 和 django 的新手，所以如果这有点疯狂，我提前道歉。

更新代码：

博客/views.py

from django.shortcuts import render, get_object_or_404, redirect
from django.contrib.auth.mixins import LoginRequiredMixin, UserPassesTestMixin
from django.contrib.auth.models import User
from django.contrib import messages
from django.db.models import Sum, Q
from django.views.generic import (
    ListView,
    DetailView,
    CreateView,
    UpdateView,
    DeleteView)
from users.forms import ProfileUpdateForm
from .models import Post, Player

class PlayersUpdateView(LoginRequiredMixin, UpdateView, Player):
    model = Player
    fields = []
    template_name = 'blog/player_form.html'  # <app>/<model>_<viewtype>.html

    def get(self, request, *args, **kwargs):
        form = ProfileUpdateForm()
        return render(request=request, template_name=self.template_name, context={
            "form": form
    })

    def post(self, request, *args, **kwargs):
        form = ProfileUpdateForm(request.POST)
        if form.is_valid():
            if request.user.players_owned <= 5:
                form.instance.player_owner = self.request.user
                request.user.players_owned = request.user.players_owned + 1
                request.user.save()
                return redirect("players-update")
            else:
                messages.error(request, "Sorry, you already have the max number of players on your roster")
            return render(request, self.template_name, {'form': form})

问题：我应该Profile从 users/models.py 导入模型吗？也许这个def不属于PlayerUpdateView？

博客/models.py：没有改变

博客/player_form.html

{% extends "blog/base.html" %}
{% load crispy_forms_tags %}
{% block content %}
<head>
    <script>
        {% if messages %}
            {% for message in messages %}
                alert(message);
            {% endfor %}
        {% endif %}
    </script>
</head>
<div class="content-section">
    <form method="POST">
        {% csrf_token %}
        <fieldset class="form-group">
            <legend class="border-bottom mb-4">Adding {{ object.player_full }}</legend>
                <img class="rounded-circle article-img" src="{{ object.image.url }}">
            {{ form|crispy }}
            <h4>Are you sure you want to add <kbd>{{ object.player_full }}</kbd> to your team?</h4>
        </fieldset>
        <div class="form-group">
            <button class="btn btn-outline-success" type="submit">Add Player</button>
            <a class="btn btn-outline-secondary" href="{% url 'players-detail' object.id %}">Cancel</a>
        </div>
    </form>
</div>
{% endblock content %}

用户/模型.py

from django.core.validators import MinValueValidator, MaxValueValidator
from django.db import models
from django.contrib.auth.models import User
from PIL import Image

class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    image = models.ImageField(default='default.jpg', upload_to='profile_pics')
    players_owned = models.PositiveSmallIntegerField(default=0,
                                                 validators [MinValueValidator(0), MaxValueValidator(15)])

用户/forms.py

from django import forms
from django.contrib.auth.models import User
from django.contrib.auth.forms import UserCreationForm
from .models import Profile


class UserRegisterForm(UserCreationForm):
    email = forms.EmailField()

    class Meta:
        # when submitted creates ...user
        model = User
        # these are the fields we want on our form
        fields = ['username', 'email', 'password1', 'password2']


class UserUpdateForm(forms.ModelForm):
    email = forms.EmailField()

    class Meta:
        # when submitted updates ...user
        model = User
        # these are the fields we want on our form
        fields = ['username', 'email']


class ProfileUpdateForm(forms.ModelForm):
    class Meta:
        model = Profile
        fields = ['image', 'players_owned']

问题：我应该UserUpdateForm改用吗？

顺便说一句，这是我得到的最新错误：

NoReverseMatch at /players/529/update/
Reverse for 'players-detail' with arguments '('',)' not found. 1 
pattern(s) tried: ['players/(?P<pk>[0-9]+)/$']
Request Method: GET
Request URL:    http://127.0.0.1:8000/players/529/update/
Django Version: 3.0.7
Exception Type: NoReverseMatch
Exception Value:    
Reverse for 'players-detail' with arguments '('',)' not found. 1 
pattern(s) tried: ['players/(?P<pk>[0-9]+)/$']

标签： pythondjangodjango-modelsdjango-formsdjango-views

解决方案

只需修改视图的 form_valid 元素以检查 player_owned：

- - -编辑

这是我喜欢使用 get 和 post 请求创建基于类的视图的方式，然后您可以访问请求对象。如果这与您的原始代码相差太大，并且您想保留该form_valid功能，请告诉我，我可以尝试将其更改为更接近您当前的功能。

from django.contrib import messages

类 PlayersUpdateView(LoginRequiredMixin, UpdateView, Player):

template_name = "template_name.html"

def get(self, request):
    form = FORM_NAME()
    return render(request=request, template_name=self.template_name, context={
        "form": form
    })
def post(self, request): 
    form = FORM_NAME(request.POST)
    if form.is_valid():
            if request.user.players_owned <= 15:
                form.instance.player_owner = self.request.user
                request.user.players_owned = request.user.players_owned + 1
                request.user.save()
                return redirect("wherever you want to go on success")
            else:
                messages.error(request, "Sorry, you already have your max number of players on your roster")
            return render(request, self.template_name, {'form': form})

---编辑结束

然后在您的模板中添加它以显示消息，在这种情况下这是一个错误。如果要再次显示表单，请使用{{form.as_p}}：

<html>
    <head>
        <script>
            {% if messages %}
                {% for message in messages %}
                    alert(message);
                {% endfor %}
            {% endif %}
        </script>
    </head>
    <body>
        {{form.as_p}}
    </body>
</html>

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