python - 改进 Python/django View 代码

Question

我对 Python/Django 和一般编程还很陌生。在我的编程包中有限的工具中，我编写了三个用户注册后的 View 函数:它允许用户在激活他的帐户之前添加信息和上传缩略图。

我已经发布了我到目前为止编写的代码，以便比我更有经验的人可以告诉我如何改进代码。毫无疑问，这是带有所有新手标记的粗略代码，但我从编写代码中学到了最好的东西——找到改进它的方法和学习新工具——然后重写它。

我知道回答这个问题需要相当长的时间。因此，我会为这个问题奖励 200 点赏金。 所以只允许我在问题发布两天后添加赏金，所以我会在星期二为这个问题添加赏金(一旦可以添加)。请注意，由于在发布悬赏之前我不会选择答案，因此在添加悬赏之前提供的答案仍然“好像”问题有悬赏

以下是我自己注释的代码。特别是，我有很多样板代码用于每个函数的前 10-14 行，根据用户是否登录、是否已经填写此信息、是否有 session 信息等来重定向用户。

# in model.py
choices = ([(x,str(x)) for x in range(1970,2015)])
choices.reverse()

class UserProfile(models.Model):
    """
    Fields are user, network, location, graduation, headline, and position.
    user is a ForeignKey, unique = True (OneToOne). network is a ForeignKey.
    loation, graduation, headline, and position are optional.
    """
    user = models.ForeignKey(User, unique=True)
    network = models.ForeignKey(Network)
    location = models.CharField(max_length=100, blank=True)
    graduation = models.CharField(max_length=100, blank=True, choices=choices)
    headline = models.CharField(max_length=100, blank=True)
    positions = models.ManyToManyField(Position, blank=True)
    avatar = models.ImageField(upload_to='images/%Y/%m/%d', blank=True, default='default_profile_picture.jpg')
    # if the user has already filled out the 'getting started info', set boolean=True
    getting_started_boolean = models.BooleanField(default=False) 

一般背景: 用户注册后，我给他们两个 session 变量:

    request.session['location'] = get_location_function(request)
    request.session['username'] = new_user   # this is an email address

用户注册后，他们将被重定向到 getting_started 页面。

第一页:

# in views.py

def getting_started_info(request, positions=[]):
    """
    This is the first of two pages for the user to
    add additional info after they have registrered.
    There is no auto log-in after the user registers,
    so the individiaul is an 'inactive user' until he
    clicks the activation link in his email.
    """
    location = request.session.get('location')
    if request.user.is_authenticated():
        username = request.user.username        # first see if the user is logged in
        user = User.objects.get(email=username) # if so, get the user object
        if user.get_profile().getting_started_boolean: 
             return redirect('/home/')                       # redirect to User home if user has already filled out  page
        else:
            pass
    else:                                                   
        username = request.session.get('username', False)    # if not logged in, see if session info exists from registration
        if not username:
            return redirect('/account/login')                # if no session info, redirect to login page
        else:
            user = User.objects.get(email=username)
    if request.method == 'POST':
          if 'Next Step' in request.POST.values():      # do custom processing on this form
              profile = UserProfile.objects.get(user=user)
              profile.location = request.POST.get('location')
              populate_positions = []
              for position in positions:
                  populate_positions.append(Position.objects.get(label=position))
              profile.positions = request.POST.get('position')
              profile.headline = request.POST.get('headline') 
              profile.graduation = request.POST.get('graduation') 
              profile.save()
              return redirect('/account/gettingstarted/add_pic/')         
    else:
        form = GettingStartedForm(initial={'location': location})
    return render_to_response('registration/getting_started_info1.html', {'form':form, 'positions': positions,}, context_instance=RequestContext(request))

第二页:

def getting_started_pic(request):
    """
    Second page of user entering info before first login.
    This is where a user uploads a photo.
    After this page has been finished, set getting_started_boolean = True,
    so user will be redirected if hits this page again.
    """
    if request.user.is_authenticated():
        username = request.user.username                      
        user = User.objects.get(email=username)            
        if user.get_profile().getting_started_boolean: 
             return redirect('/home/')                      
        else:
            pass
    else:                                                   
        username = request.session.get('username', False)    
        if not username:
            return redirect('/account/login')                
        else:
            user = User.objects.get(email=username)
    try:
        profile = UserProfile.objects.get(user=User.objects.get(email=username)) # get the profile to display the user's picture
    except UserProfile.DoesNotExist:        # if no profile exists, redirect to login 
        return redirect('/account/login')   # this is a repetition of "return redirect('/account/login/')" above
    if request.method == 'POST':
        if 'upload' in request.POST.keys():
            form = ProfilePictureForm(request.POST, request.FILES, instance = profile)
            if form.is_valid():
                if UserProfile.objects.get(user=user).avatar != 'default_profile_picture.jpg': # if the user has an old avatar image
                    UserProfile.objects.get(user=user).avatar.delete()   # delete the image file unless it is the default image
                object = form.save(commit=False)
                try:
                    t = handle_uploaded_image(request.FILES['avatar']) # do processing on the image to make a thumbnail
                    object.avatar.save(t[0],t[1])
                except KeyError:
                    object.save()
                return render_to_response('registration/getting_started_pic.html', {'form': form, 'profile': profile,}, context_instance=RequestContext(request))
        if 'finish' in request.POST.keys():
            UserProfile.objects.filter(user=user).update(getting_started_boolean='True') # now add boolean = True so the user won't hit this page again
            return redirect('/account/gettingstarted/check_email/')       
    else:
        form = ProfilePictureForm()
    return render_to_response('registration/getting_started_pic.html', {'form': form, 'profile': profile,}, context_instance=RequestContext(request))

第三页:

def check_email(request):
    """
    End of getting started. Will redirect to user home
    if activation link has been clicked. Otherwise, will
    allow user to have activation link re-sent.
    """
    if request.user.is_authenticated():    # if the user has already clicked his activation link, redirect to User home
        return redirect('/home/')
    else:                                  # if the user is not logged in, load this page
        resend_msg=''
        user = email = request.session.get('username')
        if not email:
            return redirect('/account/login/')
        if Site._meta.installed:
            site = Site.objects.get_current()
        else:
            site = RequestSite(request)
        if request.method == 'POST':
            RegistrationProfile.objects.resend_activation(email, site)
            resend_msg = 'An activation email has been resent to %s' %(email)
            return render_to_response('registration/getting_started_check_email.html', {'email':email, 'resend_msg':resend_msg}, context_instance=RequestContext(request))
        return render_to_response('registration/getting_started_check_email.html', {'email':email, 'resend_msg':resend_msg}, context_instance=RequestContext(request))

Answer 1

我会做一些不同的事情:

1. 在您的 models.py 中，您将 choices 参数用于您的 graduation 字段，但不要在模型上定义选项，也不要使用通常用于表示 Python 中常量的全部大写。这样会更好:

   class UserProfile(models.Model):
       ...
       CHOICES = [('choice1', 'Choice 1'), ('choice2', 'Choice2')]
       graduation = models.CharField(max_length=100, blank=True, choices=CHOICES)
   

2. 您在avatar 字段中使用可选的default。使用 blank=True 会更有意义，在您看来，它实际上会使您以后的逻辑复杂化:

   if UserProfile.objects.get(user=user).avatar != 'default_profile_picture.jpg':
       UserProfile.objects.get(user=user).avatar.delete()
   

   相反，最好只处理模板中缺少头像的问题。

3. 在您的 getting_started_info View 中，positions 的默认参数是一个可变对象，positions=[]。总的来说，这让我感到畏缩，尽管在你的事业中它不会给你带来任何问题，因为它从未发生过变异。避免在 Python 中使用可变对象作为默认参数是个好主意，因为 function definitions are only evaluated once .最好避免这种情况。

   >>> def foo(l=[]):
   ...:     l.append(1)
   ...:     return l
   ...: 
   
   >>> foo()
   <<< [1]
   
   >>> foo()
   <<< [1, 1]
   
   >>> foo()
   <<< [1, 1, 1]
   

4. 你做 else: pass，这是多余的，完全删除 `else'。

   if user.get_profile().getting_started_boolean:
       return redirect('/home/')
   # else:   
   #    pass
   

如果以后有机会，我会再讨论一些关于您处理事情的方式的问题。