为什么django form.as_p在渲染模板时调用form.clean方法? [英] Why django form.as_p call form.clean method when template renders?

问题描述

我有这个django代码示例:

I have this sample of django code:

# views.py
def test_view(request):
    form = TestForm(
        request.POST or { 'text': 'some text'},
    )
    data = {
        'form': form,
    }
    print 'before rendering'
    return render(request, 'test.html', data)

# forms.py
class TestForm(forms.Form):
    text = forms.CharField()

    def __init__(self, *args, **kwargs):
        print 'init'
        super(TestForm, self).__init__(*args, **kwargs)

    def clean(self):
        print 'in clean'

和此模板:

#test.html
<form id='test-form' method="post" action="some url" enctype="multipart/form-data">
    {{ form.as_p }}
    <input type="submit" value="Save"/>
</form>

当我向该文件发送获取请求时，我在控制台中有以下输出:

when i send get request to this file i have this output in console:

在呈现
init
干净之前

before rendering
init
in clean

当我写{{form.text}}而不是{{form.as_p}}时，我只有:

when I write {{ form.text }} instead of {{ form.as_p }} I have only:

渲染前
init

before rendering
init

在我看来，as_p方法在呈现模板的过程中内部调用了clean(). 在此之前，我提到过as_p方法只是某种捷径(我知道这是Form类的一种方法)，并且没有实现逻辑.
为什么会发生?是错误还是有用的功能?

It seams to me that as_p method calls clean() internally in process of rendering template. Before that I mentioned that as_p method only is some kind of shortcut(I understand that it's a method of Form class) and doesn't realize logic.
Why does it happen? Is it a bug or some usefull feature?

Django的版本== 1.5.1

Version of Django==1.5.1

推荐答案

像这样更改视图:

# views.py
def test_view(request):

    if request.POST:
        form = TestForm(request.POST)
        # this is usually used when there's an actual post request
        # and in this block you do validation
    else:
        form = TestForm(initial={'somekey': 'somevalue'})

    data = {
        'form': form,
    }
    print 'before rendering'
    return render(request, 'test.html', data)

和clean()将不再被调用

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