Django/Python - Collect the data to the right form (Algorithm) -

i have models this:

item:     name     desc  attrgroup:     name     order  attrname:     name     group.foreinkey(attrgroup)     order  attrval:     value     attr.foreinkey(attrname)     item.foreinkey(item) 

so want compare attributes of n items in list items_id=[1,3,7,...]

in views, likes this:

attrs = attrval.object.filter(item__id__in=items_id) 

and send templates. i'm gonna confusing way how arrange list interface.

the templates should this:

<table>     {% g in group %}         <tr class="group_name">{{ g.name }}</tr>         {% in attrs %}         <tr>             <td>{{ a.name }}</td>             {% in items_id %}                 <td>{{ value of item 'i' }}</td>             { %endfor %}         </tr>         {% endfor %}     {% endfor %} </table> 

i think have solution issue. thanks!

update: follow pretty solution @lott, found out way how show data templates. i'm using code likes this:

{% g in groups %}     <tr class="title_row">         <td class="group_name" colspan="{{ no_items }}">{{ g.0 }}</td>     </tr>      {% in g.1 %}     <tr>         <td>{{ a.attr.name }}</td>         {% in comparing_items %}             <td>{% if a.item.id == %}{{ a.value }}{% endif %}</td>         {% endfor %}     </tr>     {% endfor %} {% endfor %} 

and appears:

<table>     <tr>         <td>attr name 1</td>         <td>attr value of item 1</td>         <td></td>         <td></td>         <td></td>     </tr>     <tr>         <td>attr name 2</td>         <td>attr value of item 1</td>         <td></td>         <td></td>         <td></td>     </tr>     <tr>         <td>attr name 1</td>         <td></td>         <td></td>         <td></td>         <td>attr value of item 4</td>     </tr> </table> 

my goal list same attribute of items [1,2,3,...] in same row. html should this:

<table>     <tr>         <td>attr name 1</td>         <td>attr value of item 1</td>         <td>attr value of item 2</td>         <td>attr value of item 3</td>         <td>attr value of item n</td>     </tr>     <tr>         <td>attr name 2</td>         <td>attr value of item 1</td>         <td>attr value of item 2</td>         <td>attr value of item 3</td>         <td>attr value of item n</td>     </tr>     <tr>         <td>attr name m</td>         <td>attr value of item 1</td>         <td>attr value of item 2</td>         <td>attr value of item 3</td>         <td>attr value of item n</td>     </tr> </table> 

thank much!

in view function can can find attrname , attrgroup each attrvalue in attrs query set. create relevant groups in view function. display details in template.

groups = defaultdict( list ) in attrs:     groups[a.attr.group.order, a.attr.group.name].append( )  group_list = [ (name[1], groups[name]) name in sorted( groups.keys() ) ] 

your template this

<table>     {% g in group_list %}         <tr class="group_name">{{ g.0 }}</tr>         {% in g.1 %}         <tr>             <td>{{ a.name }}</td>             {% in a.item %} <!-- yes, can refer methods of model objects. -->                 <td>{{ }}</td>             { %endfor %}         </tr>         {% endfor %}     {% endfor %} </table>