Django表单与视图开发全解析

### Django表单与视图开发全解析 #### 1. 表单字段与视图基础 在开发中，除了常规字段，我们还能传递HTML片段，例如在图像字段的帮助块中就可以这样操作。同时，在布局里可以使用前置文本字段，像给电话字段添加电话图标，给邮箱字段添加@符号。借助Div对象，能轻松将字段包装进HTML的`<div>`元素，这在需要对某些表单字段应用特定JavaScript时非常有用。 HTML表单的`action`属性由表单助手的`form_action`属性定义，`method`属性由`form_method`属性定义。此外，还有一个`Submit`对象用于渲染提交按钮，其第一个位置参数是按钮名称，第二个参数是按钮的值。 若项目需要特定的表单标记，可以覆盖和修改`django-crispy-forms`应用的模板。因为Python文件中没有硬编码的标记，所有生成的标记都是通过模板渲染的。只需将`django-crispy-forms`应用的模板复制到项目的模板目录，然后按需修改即可。 #### 2. 过滤对象列表 在Web开发中，除了表单视图，对象列表视图和详细视图也很常见。简单的列表视图按字母顺序或创建日期排列对象，但处理大量数据时不太友好。为了提高可访问性和便利性，应能按所有可能的类别过滤内容。 以下是实现过滤对象列表的步骤： - **准备工作**：使用具有与流派、导演、演员关系的`Movie`模型进行过滤，同时可以按评级过滤。创建`movies`应用，并在设置的`INSTALLED_APPS`中添加该应用，然后在新应用中定义相关模型。 ```python # movies/models.py # -*- coding: UTF-8 -*- from django.db import models from django.utils.translation import ugettext_lazy as _ RATING_CHOICES = ( (1, u"¶"), (2, u"¶¶"), (3, u"¶¶¶"), (4, u"¶¶¶¶"), (5, u"¶¶¶¶¶"), ) class Genre(models.Model): title = models.CharField(_("Title"), max_length=100) def __unicode__(self): return self.title class Director(models.Model): first_name = models.CharField(_("First name"), max_length=40) last_name = models.CharField(_("Last name"), max_length=40) def __unicode__(self): return self.first_name + " " + self.last_name class Actor(models.Model): first_name = models.CharField(_("First name"), max_length=40) last_name = models.CharField(_("Last name"), max_length=40) def __unicode__(self): return self.first_name + " " + self.last_name class Movie(models.Model): title = models.CharField(_("Title"), max_length=255) genres = models.ManyToManyField(Genre, blank=True) directors = models.ManyToManyField(Director, blank=True) actors = models.ManyToManyField(Actor, blank=True) rating = models.PositiveIntegerField(choices=RATING_CHOICES) def __unicode__(self): return self.title ``` - **创建过滤表单**：创建包含所有可能过滤类别的`MovieFilterForm`。 ```python # movies/forms.py # -*- coding: UTF-8 -*- from django import forms from django.utils.translation import ugettext_lazy as _ from models import Genre from models import Director from models import Actor from models import RATING_CHOICES class MovieFilterForm(forms.Form): genre = forms.ModelChoiceField( label=_("Genre"), required=False, queryset=Genre.objects.all(), ) director = forms.ModelChoiceField( label=_("Director"), required=False, queryset=Director.objects.all(), ) actor = forms.ModelChoiceField( label=_("Actor"), required=False, queryset=Actor.objects.all(), ) rating = forms.ChoiceField( label=_("Rating"), required=False, choices=RATING_CHOICES, ) ``` - **创建视图**：创建`movie_list`视图，使用`MovieFilterForm`验证请求查询参数，并按所选类别进行过滤。 ```python # movies/views.py # -*- coding: UTF-8 -*- from django.shortcuts import render from models import Genre from models import Director from models import Actor from models import Movie, RATING_CHOICES from forms import MovieFilterForm def movie_list(request): qs = Movie.objects.order_by('title') form = MovieFilterForm(data=request.REQUEST) facets = { 'selected': {}, 'categories': { 'genres': Genre.objects.all(), 'directors': Director.objects.all(), 'actors': Actor.objects.all(), 'ratings': RATING_CHOICES, }, } if form.is_valid(): genre = form.cleaned_data['genre'] if genre: facets['selected']['genre'] = genre qs = qs.filter(genres=genre).distinct() director = form.cleaned_data['director'] if director: facets['selected']['director'] = director qs = qs.filter(directors=director).distinct() actor = form.cleaned_data['actor'] if actor: facets['selected']['actor'] = actor qs = qs.filter(actors=actor).distinct() rating = form.cleaned_data['rating'] if rating: facets['selected']['rating'] = \ (int(rating), dict(RATING_CHOICES)[int(rating)]) qs = qs.filter(rating=rating).distinct() context = { 'form': form, 'facets': facets, 'object_list': qs, } return render(request, "movies/movie_list.html", context) ``` - **创建模板**：创建列表视图的模板，使用`facets`字典列出类别，并标记当前选中的类别。 ```html {# templates/movies/movie_list.html #} {% extends "base_two_columns.html" %} {% load i18n utility_tags %} {% block sidebar %} <div class="filters"> <h6>{% trans "Filter by Genre" %}</h6> <div class="list-group"> <a class="list-group-item{% if not facets.selected.genre %} active{% endif %}" href="{% append_to_query genre="" page="" %}">{% trans "All" %}</a> {% for cat in facets.categories.genres %} <a class="list-group-item{% if facets.selected.genre == cat %} active{% endif %}" href="{% append_to_query genre=cat.pk page="" %}">{{ cat }}</a> {% endfor %} </div> <h6>{% trans "Filter by Director" %}</h6> <div class="list-group"> <a class="list-group-item{% if not facets.selected.director %} active{% endif %}" href="{% append_to_query director="" page="" %}">{% trans "All" %}</a> {% for cat in facets.categories.directors %} <a class="list-group-item{% if facets.selected.director == cat %} active{% endif %}" href="{% append_to_query director=cat.pk page="" %}">{{ cat }}</a> {% endfor %} </div> <h6>{% trans "Filter by Actor" %}</h6> <div class="list-group"> <a class="list-group-item{% if not facets.selected.actor %} active{% endif %}" href="{% append_to_query actor="" page="" %}">{% trans "All" %}</a> {% for cat in facets.categories.actors %} <a class="list-group-item{% if facets.selected.actor == cat %} active{% endif %}" href="{% append_to_query actor=cat.pk page="" %}">{{ cat }}</a> {% endfor %} </div> <h6>{% trans "Filter by Rating" %}</h6> <div class="list-group"> <a class="list-group-item{% if not facets.selected.rating %} active{% endif %}" href="{% append_to_query rating="" page="" %}">{% trans "All" %}</a> {% fo ```