通过 django-taggit 的标签实例未按更新帖子表单中的预期呈现

Question

检索问题实例时，

{{ form.tags | as_crispy_field }}

未按预期呈现。在创建初始帖子时，相同的脆皮表单语法可以完美地工作和呈现

按提交会导致服务器 500 错误。测试结果内联记录：

<!-- templates/update_question.html -->
{% extends "base.html" %}
{% load static %}
{% load crispy_forms_tags %}

{% block extra_head %}
<!-- django-quill-editor Media -->
{% include 'django_quill/media.html' %}
{% endblock %}

{% block content %}

<main class="flex-shrink-0 main-bg">
    <div class="container-question my-5">
[...]
        <form id="standards-form" method="post" action="{% url 'question_update' slug=question.slug %}">
            {% csrf_token %}
        [...]
            
            <h2 class="text-center">Subject line</h2>
            {{ form.subject | as_crispy_field }} <!-- rendering as expected-->

            
            <br>
            <h2 class="text-center">Details</h2>
            {{ form.content | as_crispy_field }} <!-- rendering as expected-->
            <br>
            <h2 class="text-center">Tags</h2>
            <div class="tag-input">
                <div class="input">
                    <div>
                        <i class="fa fa-tags"></i>
                        {{ form.tags | as_crispy_field }} <!--not rendering as expected: reading as [<Tag: tag1>, <Tag: tag2>, <Tag: tag3>]. Expecting tag1 tag2 tag3 to be retrieved from django-taggit's TaggableManager-->
                    </div>
                </div>
                <div class="tag-list mb-4"></div>
            </div>
            <button type="submit" class="btn btn-primary " id="question-submit">Submit</button>
        </form>
        
    </div>

</main>

{% endblock %}

调试步骤

表单在此类中处理，我尝试过打印日志并将 init 函数移至顶部。

# main_forum/forms/question_form.py

# This file contains the form for the Question model. The QuestionForm class will be used to create and update questions in the forum.

from django import forms
from django.contrib.auth.models import User
from crispy_forms.helper import FormHelper
from crispy_forms.layout import Submit
from ..models import Question, Answer
from django_quill.forms import QuillFormField
from taggit.forms import TagField
from django.contrib.auth.forms import PasswordChangeForm


class QuestionForm(forms.ModelForm):
    [...]
    tags = forms.CharField(required=False)

    class Meta:
        model = Question  # Specifies the model in models.py associated with this form
        fields = ['subject', 'content', 'tags']

    def __init__(self, *args, **kwargs):
        """
        This is for checking if the form is bound to an existing instance, i.e. if the form is being used to update an existing question.
        """
        super(QuestionForm, self).__init__(*args, **kwargs)
        [...]

        if self.instance.pk: 
            self.fields['tags'].initial = ' '.join(tag.name for tag in self.instance.tags.all()) # Pre-populate the tags field with the existing tags
            print('tags initial:', self.fields['tags'].initial) # PASS. prints as  tags initial: tag1 tag2 tag3

    [...]

    def clean_tags(self):
        tags = self.cleaned_data.get('tags', '')
        return tags

    def save(self, *args, **kwargs):
        instance = super(QuestionForm, self).save(commit=False)
        instance.save()

        # Handling tags here
        tags = self.cleaned_data.get('tags', '')
        tag_names = tags.split()
        print('tag_names after tag.split', tag_names) # expecting ['tag1', 'tag2', 'tag3'] in order to be saved correctly etc. PASS
        instance.tags.clear()

        for tag_name in tag_names:
            instance.tags.add(tag_name.strip())  # Ensure tag is stripped of extra whitespace

        print('instance.tags.all:', instance.tags.all()) # PASS <QuerySet [<Tag: tag1>, <Tag: tag2>, <Tag: tag3>]> etc.

        if self.instance.pk:
            # If this is an update, save the instance again
            instance.save()  # Save the instance again to save the many-to-many relationships
            print('instance saved:', instance) # testing: leads to server 500 error

        return instance

Answer 1

看来我能找到的最佳解决方案是替换 {{ form.tags | as_crispy_field }} 带有自定义输入：

<input type="text" name="tags" id="id_tags id_tags_update" value="{{ question.tags.all|join:' ' }}" /> <!-- this correctly renders the tags as tag1 tag2 tag3 etc.-->