如何对表格中的Django元素列进行排序？

Question

如何对表中的Django元素列进行排序？

我注意到Django Admin会这样做。怎么样？

任何可用的网络资源，我可以在这里读到？

*通过“Django的元素”，我指的是像这样的可插拔模板对象：

{{ x.y }} 

Answer 1

如果你从一个查询得到它然后使用在视图中order_by()方法。如果是列表，则在视图中使用sort()方法。

Answer 2

值得一看在Django管理变更列表查看源代码：

http://code.djangoproject.com/svn/django/branches/releases/1.2.X/django/contrib/admin/views/main.py

订购过程大致是：

1. 单击列标题在管理，这将重新加载网页中的相关订单参数在url中，请求中可用.GET

2. 此订单参数进行解析在变更表视图：

   self.order_field，self.order_type = self.get_ordering（）被生成

3. 查询集：

   self.query_set = self.get_query_set（） INparticular，函数中的以下行： if self.order_field： qs = qs.order_by（'％s％s'％（（self.order_type =='desc'and' - 'or''），self.order_field） ）

在理解源代码的同时使用django管理员是我认为学习django的最佳方法之一！

Answer 3

我在查看管理员如何在Django 0.96中执行操作后创建了此实用程序类。

它根据GET参数处理order_by条件的创建，并提供上下文变量用于生成关于当前排序字段和方向的表格标题排序链接，当相同标题再次排序时颠倒方向。

ORDER_VAR = 'o' 
ORDER_TYPE_VAR = 'ot' 

class SortHeaders: 
    """ 
    Handles generation of an argument for the Django ORM's 
    ``order_by`` method and generation of table headers which reflect 
    the currently selected sort, based on defined table headers with 
    matching sort criteria. 

    Based in part on the Django Admin application's ``ChangeList`` 
    functionality. 
    """ 
    def __init__(self, request, headers, default_order_field=None, 
      default_order_type='asc', additional_params=None): 
     """ 
     request 
      The request currently being processed - the current sort 
      order field and type are determined based on GET 
      parameters. 

     headers 
      A list of two-tuples of header text and matching ordering 
      criteria for use with the Django ORM's ``order_by`` 
      method. A criterion of ``None`` indicates that a header 
      is not sortable. 

     default_order_field 
      The index of the header definition to be used for default 
      ordering and when an invalid or non-sortable header is 
      specified in GET parameters. If not specified, the index 
      of the first sortable header will be used. 

     default_order_type 
      The default type of ordering used - must be one of 
      ``'asc`` or ``'desc'``. 

     additional_params: 
      Query parameters which should always appear in sort links, 
      specified as a dictionary mapping parameter names to 
      values. For example, this might contain the current page 
      number if you're sorting a paginated list of items. 
     """ 
     if default_order_field is None: 
      for i, (header, query_lookup) in enumerate(headers): 
       if query_lookup is not None: 
        default_order_field = i 
        break 
     if default_order_field is None: 
      raise AttributeError('No default_order_field was specified and none of the header definitions given were sortable.') 
     if default_order_type not in ('asc', 'desc'): 
      raise AttributeError('If given, default_order_type must be one of \'asc\' or \'desc\'.') 
     if additional_params is None: additional_params = {} 

     self.header_defs = headers 
     self.additional_params = additional_params 
     self.order_field, self.order_type = default_order_field, default_order_type 

     # Determine order field and order type for the current request 
     params = dict(request.GET.items()) 
     if ORDER_VAR in params: 
      try: 
       new_order_field = int(params[ORDER_VAR]) 
       if headers[new_order_field][1] is not None: 
        self.order_field = new_order_field 
      except (IndexError, ValueError): 
       pass # Use the default 
     if ORDER_TYPE_VAR in params and params[ORDER_TYPE_VAR] in ('asc', 'desc'): 
      self.order_type = params[ORDER_TYPE_VAR] 

    def headers(self): 
     """ 
     Generates dicts containing header and sort link details for 
     all defined headers. 
     """ 
     for i, (header, order_criterion) in enumerate(self.header_defs): 
      th_classes = [] 
      new_order_type = 'asc' 
      if i == self.order_field: 
       th_classes.append('sorted %sending' % self.order_type) 
       new_order_type = {'asc': 'desc', 'desc': 'asc'}[self.order_type] 
      yield { 
       'text': header, 
       'sortable': order_criterion is not None, 
       'url': self.get_query_string({ORDER_VAR: i, ORDER_TYPE_VAR: new_order_type}), 
       'class_attr': (th_classes and ' class="%s"' % ' '.join(th_classes) or ''), 
      } 

    def get_query_string(self, params): 
     """ 
     Creates a query string from the given dictionary of 
     parameters, including any additonal parameters which should 
     always be present. 
     """ 
     params.update(self.additional_params) 
     return '?%s' % '&'.join(['%s=%s' % (param, value) \ 
            for param, value in params.items()]) 

    def get_order_by(self): 
     """ 
     Creates an ordering criterion based on the current order 
     field and order type, for use with the Django ORM's 
     ``order_by`` method. 
     """ 
     return '%s%s' % (
      self.order_type == 'desc' and '-' or '', 
      self.header_defs[self.order_field][1], 
     ) 

样的看法：

from somewhere import SortHeaders 
from django.contrib.auth.models import User 
from django.shortcuts import render_to_response 

LIST_HEADERS = (
    ('Username', 'username'), 
    ('First Name', 'first_name'), 
    ('Last Name', 'last_name'), 
    ('Email', None), 
) 

def user_list(request): 
    sort_headers = SortHeaders(request, LIST_HEADERS) 
    users = User.objects.order_by(sort_headers.get_order_by()) 
    return render_to_response('users/user_list.html', { 
     'users': users, 
     'headers': list(sort_headers.headers()), 
    }) 

样品模板（users/user_list.html）：

{% load my_tags %} 
<table cellspacing="0"> 
<thead> 
    <tr> 
{% table_header headers %} 
    </tr> 
</thead> 
<tbody> 
    {% for user in users %}<tr class="{% cycle odd,even %}"> 
    <td><a href="{{ user.get_absolute_url }}">{{ user.username }}</a></td> 
    <td>{{ user.first_name }}</td> 
    <td>{{ user.last_name }}</td> 
    <td>{{ user.email }}</td> 
    </tr> 
    {% endfor %} 
</tbody> 
</table> 

样品包含标签（templatetags/my_tags.py）：

from django import template 

def table_header(context, headers): 
    return { 
     'headers': headers, 
    } 

register = template.Library() 
register.inclusion_tag('table_header.html', takes_context=True)(table_header) 

样品包含标签TEMPL （table_header.html）：

{% for header in headers %}<th{{ header.class_attr }}> 
    {% if header.sortable %}<a href="{{ header.url }}">{% endif %} 
    {{ header.text }} 
    {% if header.sortable %}</a>{% endif %} 
</th>{% endfor %}