id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
9749	ModelAdmin should allow specifying Changelist class to further modify Changelist behavior	anonymous	Jannis Leidel	"I've been poking around the Django source as I want to add a column to the changelist view. Specifically, this column is a consolidation of a ManyToMany relationship. I'll use it as an example here.

In options.py, class ModelAdmin defines a function that instantiates a Changelist:
{{{
class ModelAdmin(BaseModelAdmin):
    def __init__(self, model, admin_site):
        self.model = model
        self.opts = model._meta
        self.admin_site = admin_site
        #more code

    #more code, more functions

    def changelist_view(self, request, extra_context=None):
        ""The 'change list' admin view for this model.""
        #more code here
        from django.contrib.admin.views.main import ChangeList, ERROR_FLAG
        #more code here
        try:
            cl = ChangeList(request, self.model, self.list_display, self.list_display_links, self.list_filter,
                     self.date_hierarchy, self.search_fields, self.list_select_related, self.list_per_page, self)
        #more code here
}}}
I propose the class 'ChangeList' be easily overidable, like so:
{{{
from django.contrib.admin.views.main import ChangeList, ERROR_FLAG

    class ModelAdmin(BaseModelAdmin):
        changelist_class = ChangeList
        def __init__(self, model, admin_site):
            self.model = model
            self.opts = model._meta
            self.admin_site = admin_site
            self.changelist_class = changelist_class
            #more code
    def changelist_view(self, request, extra_context=None):
        ""The 'change list' admin view for this model.""
        #more code here
        from django.contrib.admin.views.main import ChangeList, ERROR_FLAG
        #more code here
        try:
            cl = self.changelist_class(request, self.model, self.list_display, self.list_display_links, self.list_filter,
                     self.date_hierarchy, self.search_fields, self.list_select_related, self.list_per_page, self)
        #more code here
}}}

This would allow one to easily override some ChangeList methods from an admin.py file:

{{{
    from models import Object, ObjectRelationToWidget #ObjectRelationToWidget acts as the ManyToMany bridge table
    from django.contrib.admin.views.main import ChangeList

    class ObjectChangeList(ChangeList):
	    def get_results(self, request):

                r = ObjectRelationToWidget.objects.all().select_related() #this puts all the Objects and Widgets into the queryset cache
                results = []
                for obj in r:
                    r.object._v_local = {}
                    r.object._v_local['widget_name'] = r.widget.name
                    r.object.widget_name = lambda x: return x._v_local['widget_name']
                    results.append(r.object)

 	        self.result_count = len(results)
 	        self.full_result_count = len(results)
 	        self.result_list = results



     class ObjectAdmin(admin.ModelAdmin):
        changelist_class = ObjectChangeList
        list_display = [""object_name"", ""widget_name""]
}}}

Are there any thoughts on this suggestion? It is simple to add as a feature, but I suppose the usefulness may be seen as somewhat dubious. Suggestions for 'doing this better' (putting a related ManyToMany field in the admin changelist) would be appreciated, also."		closed	contrib.admin	dev		fixed	ModelAdmin Changelist subclass	www_djangoproject_com@… jarek.zgoda@… ales.zoulek@… David Larlet Salva Pinyol floguy@…	Ready for checkin	1	0	0	0	0	0