问题

我正在开发一个Django博客应用程序，我有一个用于编辑帖子的视图。但是，当我点击编辑按钮时，表单字段不会显示预填充的现有数据。

这是我的`edit_post`视图代码：

```python
def edit_post(request, post_id):
    post = get_object_or_404(Post, id=post_id)

    if request.method == "POST":
        form = PostForm(request.POST, instance=post)
        if form.is_valid():
            form.save()
            return redirect("main_page")
    else:
        form = PostForm(instance=post)

    context_dict = {
        "form": form,
        "post": post,
    }

    return render(request, "blog/edit_post.html", context_dict)

all_posts.html -> 按钮，重定向到编辑帖子页面。

edit_post.html: 表单部分的代码。

我已经确认PostForm正确配置了来自Post模型的必填字段。我还尝试过使用@never_cache装饰器，但没有解决这个问题。

我不确定为什么在提交表单后表单字段没有预填充现有数据。只有在我手动重新加载页面时才起作用。

对于如何解决这个问题的任何建议或见解，将不胜感激。

<details>
<summary>英文:</summary>

I&#39;m developing a Django blog application and I have a view to edit a post. However, when I click the Edit button, the form fields do not appear prepopulated with the existing data.

Here&#39;s my `edit_post` view code:

def edit_post(request, post_id):
post = get_object_or_404(Post, id=post_id)

if request.method == "POST":
    form = PostForm(request.POST, instance=post)
    if form.is_valid():
        form.save()
        return redirect("main_page")
else:
    form = PostForm(instance=post)

context_dict = {
    "form": form,
    "post": post,
}

return render(request, "blog/edit_post.html", context_dict)

all_posts.html -> button that redirects to the Edit Post page.

    <form method="POST" action="{% url 'edit_post' post.id %}">
        {% csrf_token %}
        <button type="submit" class="btn btn-secondary me-2 btn-sm">Edit</button>
    </form>

edit_post.html: part of the code where the form is.

    <form method="POST">
                    {% csrf_token %}
                    {{ form.media }}
                    <div class="mb-3">
                        <label for="{{ form.title.id_for_label }}" class="form-label">Title</label>
                        {{ form.title }}
                    </div>
                    <div class="mb-3">
                        <label for="{{ form.summary.id_for_label }}" class="form-label">Summary</label>
                        {{ form.summary }}
                    </div>
                    <div class="mb-3">
                        <label for="{{ form.image_url.id_for_label }}" class="form-label">Image URL</label>
                        {{ form.image_url }}
                    </div>
                    <div class="mb-3">
                        <label for="{{ form.body.id_for_label }}" class="form-label">Body</label>
                        {{ form.body }}
                    </div>
                    <div class="mb-3">
                        <label for="{{ form.tags.id_for_label }}" class="form-label">Tags</label>
                        {{ form.tags }}
                    </div>
                    <button type="submit" class="btn btn-primary">Update Post</button>
                </form>  

I have verified that the PostForm is correctly configured with the required fields from the Post model. I also tried using the `@never_cache` decorator, but it didn't resolve the issue.

I'm not sure why the form fields are not prepopulated with the existing data after submitting the form. It only works when I manually reload the page.

Any suggestions or insights on how to fix this issue would be greatly appreciated.

</details>


# 答案1
**得分**: 1

尝试以下两种方法来解决这个问题。

检查这段代码，确保你的 post 对象不为空。

```python
post = get_object_or_404(Post, id=post_id)

其次，从上下文中移除 post 对象，它不是必需的。

context_dict = {
    "form": form,
}

post = get_object_or_404(Post, id=post_id)

context_dict = {
            "form": form,
            }

答案2

得分: 1

好的，“the problem is the button”这部分是指问题出在按钮上，它会将用户带到“编辑帖子视图”。

“But your button strangely is also sending a POST request.”这部分是指但你的按钮却奇怪地也发送了一个POST请求。你需要更改这个。

“This can be just a normal link like this:”这部分是指这可以只是一个普通的链接，就像这样：

“Just because you are passing a parameter to the url does not mean that this has to be a POST request!”这部分是指仅仅因为你向URL传递了参数，并不意味着它必须是一个POST请求！

“What is happening in your case: Your post-edit-view divides its logic into POST and GET requests.”这部分是指在你的情况下发生了什么：你的“编辑帖子视图”将其逻辑分为了POST和GET请求。

“Usually you expect the GET part of the view being triggered when a user "goes" to the edit-view.”这部分是指通常你期望在用户“进入”编辑视图时会触发视图的GET部分。

“Then the form would be populated correctly via PostForm(instance=post).”这部分是指然后表单将通过PostForm(instance=post)正确填充。

“In your case you access the view already with a POST request, so the POST arm of the view gets triggered.”这部分是指在你的情况下，你已经使用了一个POST请求访问了视图，所以视图的POST部分被触发了。

“Here you don't send any data with the request, so this PostForm(request.POST, instance=post) populates the form with empty data.”这部分是指在这里，你没有在请求中发送任何数据，所以PostForm(request.POST, instance=post)会用空数据填充表单。

<a href="{% url 'edit_post' post.id %}" class="btn btn-secondary me-2 btn-sm">
  Edit
</a>