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本文介绍了Django多对多关系(类别)的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我的目标是向帖子模型添加类别。我希望以后可以按不同类别(有时甚至是多个类别)查询所有帖子。
models.py
class Category(models.Model):
类别=(
('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 = form.MultipleChoiceField(required = False,widget = forms.CheckboxSelectMultiple,
选择=类别)
类元:
模型=发布
字段=(
'text',
'类别'
)
我对保存一个的逻辑感到困惑
views.py
def post(request):
如果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')
否则:
form = Post_form()
args = {'form' :form}
return render(request,'home / new_post.html',args)
错误:
< Post:Post object>必须先使用字段 id的值,然后才能使用这种多对多关系。
编辑:
form.cleaned_data [ 'category']正在返回导致主要问题的列表。现在我的问题是我的选择没有保存到Category类的标题中,而是保存了选择号。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 =请求用户
post.save()
for k in form.cleaned_data ['category']:
p1 = Category(title = k)
p1.save()
post.category.add(p1)
已解决
views.py
def post(request):
如果需要.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')
解决方案主要问题是您在分配类别之前尚未将发布对象保存到数据库中。因此,将视图更改为以下内容
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)
My goal is to add categories to my Post model. I would like to be able to later query all post by different and sometimes multiple categories.
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'
)
I'm confused on the logic of saving one obj before you can save another.
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)
error:
"<Post: Post object>" needs to have a value for field "id" before this many-to-many relationship can be used.
EDIT:
form.cleaned_data['category'] is returning a list causing the main issue. Now my problem is my choice isn't being saved into the title of the Category class, the selection number is being saved instead. Here's what i got.
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)
SOLVED
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')
解决方案
the main problem is that you havent saved the post object to the database before assigning the Category. so change the view a bit to this
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)
这篇关于Django多对多关系(类别)的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!