編輯視圖保存兩次

Question

def edit(request, id): 
    post = get_object_or_404(Post, id=id) 
    edit_form = EditPostForm(request.POST or None, instance=post) 
    if edit_form.is_valid(): 
     instance = edit_form.save(commit=False) 
     instance.save(update_fields=['content']) 

這是我的編輯視圖來更新Post（它只更新content字段）。然而，Post會保存兩次，因此在我的查詢集中顯示兩次。我在視圖代碼中存在2個保存問題，但是我怎麼會在這裏執行編輯？

完整視圖：

def edit(request, id): 
    post = get_object_or_404(Post, id=id) 
    edit_form = EditPostForm(request.POST or None, instance=post) 
    if edit_form.is_valid(): 
     instance = edit_form.save(commit=False) 
     instance.save(update_fields=['content']) 
     return HttpResponseRedirect('/') 
    else: 
     print(edit_form.errors) 
     edit_form = PostForm(instance=post) 
    context = { 
     'edit_form': edit_form, 
     'form_post': post 
    } 
    return render(request, 'edit.html', context) 

SQL：

[11/Mar/2017 13:11:57] "GET /post/edit/192/ HTTP/1.1" 200 7394 
[11/Mar/2017 13:12:08] "POST /post/edit/192/ HTTP/1.1" 302 0 
[11/Mar/2017 13:12:08] "GET/HTTP/1.1" 302 0 
[11/Mar/2017 13:12:08] "GET /home/ HTTP/1.1" 200 20044 

EDIT

視圖

def edit(request, id): 
    post = get_object_or_404(Post, id=id) 
    print('CAT:', post.category) 
    edit_form = EditPostForm(request.POST or None, instance=post) 
    if edit_form.is_valid(): 
     print('Edit valid') 
     instance = edit_form.save(commit=False) 
     instance.save(update_fields=['content']) 
     return HttpResponseRedirect('/') 
    else: 
     print('Errors:', edit_form.errors) 
     print('Non-field Errors:', edit_form.non_field_errors) 
     edit_form = PostForm(instance=post) 
    context = { 
     'edit_form': edit_form, 
     'form_post': post 
    } 
    return render(request, 'edit.html', context) 

終端輸出時我編輯帖子：

CAT: 1 
Errors: 
Non-field Errors: <bound method BaseForm.non_field_errors of <EditPostForm bound=False, valid=False, fields=(content)>> 
[23/May/2017 04:37:22] "GET /post/edit/37/ HTTP/1.1" 200 7430 
CAT: 1 
Edit valid 

每次創建發表時間：

def create_post_score(sender, **kwargs): 
    score = PostScore.objects.create(post=kwargs['instance']) 
    print(score.upvotes) 

post_save.connect(create_post_score, sender=Post) 

Answer 1

當你在看save method它清楚地表明不存在時commit = False正在執行一個SQL命令。實際的數據庫調用在您的下一行中發生時instance.save

如果您看到兩個更新發生，可能是因爲表單正在提交兩次。這可以安全地忽略，因爲許多RDBMS足夠聰明，不會更新未更改的數據。然而，即使可以通過使用重定向的標準Django的模式表單處理後

instance = edit_form.save(commit=False) 
instance.save(update_fields=['content']) 
return HttpResponseRediret('/success_url/') 

Answer 2

您需要的視圖中的指定request.method，如果不是形式獲取請求提交也可避免。 因爲表單已經包含「post」實例，表單已經有效並且被保存。

編輯您的看法是這樣，

def edit(request, id): 
    post = get_object_or_404(Post, id=id) 
    #If it is a POST request do the thing below. 
    if request.method == "POST": 
     edit_form = EditPostForm(request.POST or None, instance=post) 
     if edit_form.is_valid(): 
      form.instance.save(update_fields=['content']) 
      return HttpResponseRedirect('/') 
    else: 
     edit_form = EditPostForm(instance=post) 
    context = { 
      'edit_form': edit_form, 
      'form_post': post 
      } 
    return render(request, 'edit.html', context)