到目前为止我们仅仅是通过视图和模板来表现数据.在本章,我们将会学习如何通过web表单来获取数据.Django包含一些表单处理功能,它使在web上收集用户信息变得简单.通过Django’s documentation on forms我们知道表单处理功能包含以下:
- 显示一个HTML表单自动生成的窗体部件(比如一个文本字段或者日期选择器).
- 用一系列规则检查提交数据.
- 验证错误的情况下将会重新显示表单.
- 把提交的表单数据转化成相关的Python数据类型.
使用Django表单功能最大的好处就是它可以节省你的大量时间和HTML方面的麻烦.这部分我们将会注重如何通过表单让用户增加目录和页面.
基本流程
流程
页面和目录表单
首先,我们需要在rango应用目录里黄建叫做forms.py文件.尽管这步我们并不需要,我们可以把表单放在models.py里,但是这将会使我们的代码简单易懂.
1 创建ModelForm类
在rango的forms.py
模块里我们将会创建一些继承自ModelForm
的类.实际上,ModelForm是一个帮助函数,它允许你在一个已经存在的模型里创建Django表单.因为我们定义了两个模型(Category和Page),我们将会分别为它们创建ModelForms.
在rango/forms.py
添加下面代码:
from django import forms
from rango.models import Page, Category
class CategoryForm(forms.ModelForm):
name = forms.CharField(max_length=128, help_text="Please enter the category name.")
views = forms.IntegerField(widget=forms.HiddenInput(), initial=0)
likes = forms.IntegerField(widget=forms.HiddenInput(), initial=0)
slug = forms.CharField(widget=forms.HiddenInput(), required=False)
# An inline class to provide additional information on the form.
class Meta:
# Provide an association between the ModelForm and a model
model = Category
fields = ('name',)
class PageForm(forms.ModelForm):
title = forms.CharField(max_length=128, help_text="Please enter the title of the page.")
url = forms.URLField(max_length=200, help_text="Please enter the URL of the page.")
views = forms.IntegerField(widget=forms.HiddenInput(), initial=0)
class Meta:
# Provide an association between the ModelForm and a model
model = Page
# What fields do we want to include in our form?
# This way we don't need every field in the model present.
# Some fields may allow NULL values, so we may not want to include them...
# Here, we are hiding the foreign key.
# we can either exclude the category field from the form,
exclude = ('category',)
#or specify the fields to include (i.e. not include the category field)
#fields = ('title', 'url', 'views')
Paste_Image.png
2 创建和增加目录视图
创建CategoryForm类以后,我们需要创建一个新的视图来展示表单并传递数据.在rango/views.py中增加如下代码.
from rango.forms import CategoryForm
def add_category(request):
# A HTTP POST?
if request.method == 'POST':
form = CategoryForm(request.POST)
# Have we been provided with a valid form?
if form.is_valid():
# Save the new category to the database.
form.save(commit=True)
# Now call the index() view.
# The user will be shown the homepage.
return index(request)
else:
# The supplied form contained errors - just print them to the terminal.
print form.errors
else:
# If the request was not a POST, display the form to enter details.
form = CategoryForm()
# Bad form (or form details), no form supplied...
# Render the form with error messages (if any).
return render(request, 'rango/add_category.html', {'form': form})
新的add_category()视图增加几个表单的关键功能.首先,检查HTTP请求方法是GET还是POST.我们根据不同的方法来进行处理 - 例如展示一个表单(如果是GET)或者处理表单数据(如果是POST) -所有表单都是相同URL.add_category()视图处理以下三种不同情况:
为添加目录提供一个新的空白表单;
保存用户提交的数据给模型,并转向到Rango主页;
如果发生错误,在表单里展示错误信息.
3 创建增加目录模板
让我们创建templates/rango/add_category.html文件.
<!DOCTYPE html>
<html>
<head>
<title>Rango</title>
</head>
<body>
<h1>Add a Category</h1>
<form id="category_form" method="post" action="/rango/add_category/">
{% csrf_token %}
{% for hidden in form.hidden_fields %}
{{ hidden }}
{% endfor %}
{% for field in form.visible_fields %}
{{ field.errors }}
{{ field.help_text }}
{{ field }}
{% endfor %}
<input type="submit" name="submit" value="Create Category" />
</form>
</body>
</html>
4 映射增加目录视图
现在我们需要映射add_category()视图.在模板里我们使用/rango/add_category/URL来提交.所以我们需要修改rango/urls.py的urlpattterns.
urlpatterns = patterns('',
url(r'^$', views.index, name='index'),
url(r'^about/$', views.about, name='about'),
url(r'^add_category/$', views.add_category, name='add_category'), # NEW MAPPING!
url(r'^category/(?P<category_name_slug>[\w\-]+)/$', views.category, name='category'),)
5 修改主页内容
作为最后一步,让我们在首页里加入链接.修改rango/index.html文件,在</body>前添加如下代码.
<a href="/rango/add_category/">Add a New Category</a><br />
6. demo
练习
add_page.htnl
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Rango - Add Page</title>
</head>
<body>
{% if category %}
<h1>Add a Page to {{ category.name }}</h1>
<form id="page_form" method="post" action="/rango/category/{{ category.slug }}/add_page/">
{% csrf_token %}
{% for hidden in form.hidden_fields %}
{{ hidden }}
{% endfor %}
{% for field in form.visible_fields %}
{{ field.errors }}
{{ field.help_text }}
{{ field }}
{% endfor %}
<input type="submit" name="submit" value="Add Page">
</form>
{% else %}
The specified category does not exist!
{% endif %}
</body>
</html>
效果图
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