Question

我的目标是为Post模型添加类别。我希望以后能够通过不同的，有时是多个类别查询所有帖子。

models.py

class Category(models.Model):
    categories = (
        ('1', 'red'),
        ('2', 'blue'),
        ('3', 'black')
    )
    title = models.CharField(max_length=50, blank=True, choices=categories)

class Post(models.Model):
    text = models.CharField(max_length=500)
    category = models.ManyToManyField(Category)

forms.py

class Post_form(forms.ModelForm):

    categories = (
        ('1', 'red'),
        ('2', 'blue'),
        ('3', 'black')
    )
    category = forms.MultipleChoiceField(required=False, widget=forms.CheckboxSelectMultiple,
    choices=categories)

    class Meta:
        model = Post
        fields = (
            'text',
            'category'
        )

我对保存一个obj的逻辑感到困惑，然后才能保存另一个obj。

views.py

def post(request):
    if request.method == 'POST':
        form = Post_form(request.POST, request.FILES)
        if form.is_valid():
            post = form.save(commit=False)
            post.user = request.user

            p1 = Category(form.cleaned_data['category'])
            post.category.add(p1)

        return redirect('home:home')

    else:
        form = Post_form()
        args = {'form': form }
        return render(request, 'home/new_post.html', args)

错误：

"<Post: Post object>" needs to have a value for field "id" before this many-to-many relationship can be used.

编辑：

form.cleaned_data ['category']返回导致主要问题的列表。现在我的问题是我的选择是没有保存到Category类的标题中，而是保存选择号。这就是我得到的。

def post(request):
    if request.method == 'POST':
        form = Post_form(request.POST, request.FILES)
        if form.is_valid():
            post = form.save(commit=False)
            post.user = request.user
            post.save()
            for k in form.cleaned_data['category']:
                p1 = Category(title=k)
                p1.save()
                post.category.add(p1)

解决

views.py

def post(request):
    if request.method == 'POST':
        form = Post_form(request.POST, request.FILES)
        if form.is_valid():
            post = form.save(commit=False)
            post.user = request.user
            post.save()

            for k in form.cleaned_data['category']:
                selection = Category.objects.get(pk=k)
                post.category.add(selection)

            return redirect('home:home')

Answer 1

主要问题是在分配类别之前没有将post对象保存到数据库。所以将视图稍微更改为此

def post(request):
if request.method == 'POST':
    form = Post_form(request.POST, request.FILES)
    if form.is_valid():
        post = form.save(commit=False)
        post.user = request.user
        post.save()
        for k in form.cleaned_data['category']:
            p1 = Category.objects.create(title=k)
            p1.save()
            post.category.add(p1)

Answer 2

像这样编辑您的视图，

if form.is_valid():
    title = form.cleaned_data['category']
    post = form.save(commit=False)
    post.user = request.user
    post.save()
    category = Category.objects.create(title=title)
    post.category.add(category)
    post.save_m2m()
    return redirect('home:home')

Django多对多关系（类别）

2 个答案: