python - pymongo.errors.InvalidOperation : cannot set options after executing query

Question

我正在使用 Flask 和 pymongo 开发一个项目，我有一个用户集合和一个电影集合，其中实例如下:

 user = {"Email":"<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="f88d8b9d8ab89f95999194d69b9795" rel="noreferrer noopener nofollow">[email protected]</a>" , "Comments":[" Hobbit 2013 :good movie" , " Hobbit 2013 :bad movie" , " Spiderman 2020 :very good"]}

我还有一个电影集合，其中电影实例如下:

movie = {"title":"Hobbit" , "year":"2013" , "comments":["Hobbit 2013 <a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="81f4f2e4f3c1e6ece0e8edafe2eeec" rel="noreferrer noopener nofollow">[email protected]</a>:good movie"] }

我正在使用 jinja 2 模板向特定电影提交新标题，如果有任何用户评论了该电影，我希望每个评论该特定电影的用户在评论中都包含新电影名称前任。对于上述用户实例，霍比特人 -> 复仇者联盟

`user = {"Email":"<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="f085839582b0979d91999cde939f9d" rel="noreferrer noopener nofollow">[email protected]</a>" , "Comments":[" Avengers  2013 :good movie" , " Avengers 2013 :bad movie" , " Spiderman 2020 :very good"]}`  
`movie = {"title":"Avengers" , "year":"2013" , "comments":["Avengers 2013 <a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="7f0a0c1a0d3f18121e1613511c1012" rel="noreferrer noopener nofollow">[email protected]</a>:good movie"] }` #obviously a movie can have more comments from users not just one 

使用 flask 端点，我成功更改了电影标题，但是我无法更改旧电影标题所在的任何用户评论，因为标题不会随我的代码变化

这是我的端点。我从 jinja2 表单中获取新标题，然后尝试用新标题替换注释中的旧标题。然后我收到错误

pymongo.errors.InvalidOperation: cannot set options after executing query

我的代码:

@app.route('/executemovieupdate' , methods = ['GET', 'POST'])
def execute_movie_update():
    if 'Email' in session and 'User' in session:
        email = session['Email']
        user = session['User']
        if user == 'Admin':
            if 'Movie' in session and 'Movie_year' in session and 'Movie_plot' in session:
                movie = session['Movie']
                old_movie  = str(movie) #store old movie title 
                print("old movie is " , old_movie)
                year = session['Movie_year']
                plot = session['Movie_plot']
                tainia = movies.find_one({'title':movie , "year":year})
                if request.method == 'POST':
                    new_title = request.form.get('new-title') #get the new title from jinja2 template 

            

                    if new_title:
                       print("update the title")
                       movies.update_one({"title":movie , "year":year} , {"$set":{"title":new_title} } ) #the title is updated succesfully for the movie 
                       session['Movie'] = new_title
                       movie = session['Movie']
                       user_list = users.find({})
                       for idxu, usr in enumerate(user_list): #this is where i try to change the title in the user comments 
                            for idxc, comment in enumerate(usr['Comments']):
                                if  old_movie in comment:
                                    print("old comment here")
                                    print(comment)
                                    user_list[idxu]['Comments'][idxc] = comment.replace(old_movie ,new_title) #this is the line where the error occurs
                                    print(comment) # the new comment is printed

                    return ''' movie has been updated '''
                                                                                                      
            else:
                return render_template('movie-update.html' , movie = tainia)        
        else:
            return redirect(url_for('admin.html'))    
    else:
        return redirect(url_for('login')) 
else:
    return redirect(url_for('login'))    

非常感谢您对这个问题的帮助。预先感谢您。

Answer 1

如果你打印 type(user_list) 你会注意到它不是一个 dict 列表，而是一个 pymongo.cursor.Cursor 对象(是只读的)，因此您可以将 user_list = users.find({}) 更改为 user_list = list(users.find({})) (但要小心它将查询集合users中的所有记录)并且它应该可以工作。

另一个更好的方法是使用 usr['Comments'][idxc] (这是一个 dict)而不是 user_list[idxu]['Comments '][idxc]

如果您想将该记录更新到 MongoDB，那么您将需要像上面一样使用 update_one

我没有你的数据，但类似这样的东西应该可以解决问题:

for idxu, usr in enumerate(user_list): #this is where i try to change the title in the user comments 
    for idxc, comment in enumerate(usr['Comments']):
        if  old_movie in comment:
            print("old comment here")
            print(comment)
            usr['Comments'][idxc] = comment.replace(old_movie ,new_title) #this is the line where the error occurs
            print(comment) # the new comment is printed
    users.update_one({"_id": usr['_id']}, {"$set": {"Comments": usr['Comments']}})