[Solved]-Django admin search: how to override the default handler?

It is very easy to do this in django 1.6

ModelAdmin.get_search_results(request, queryset, search_term) New in Django 1.6.

import operator
# from django.utils.six.moves import reduce  # if Python 3
from django.db.models import Q

class PersonAdmin(admin.ModelAdmin):
    list_display = ('name', 'age')
    search_fields = ('name',)

    def get_search_results(self, request, queryset, search_term):
        # search_term is what you input in admin site
        # queryset is search results
        queryset, use_distinct = super(PersonAdmin, self).get_search_results(request, queryset, search_term)

        search_term_list = search_term.split(' ')#['apple','bar']
        # you can also use `self.search_fields` instead of following `search_columns`
        search_columns = ('name','age','address')
        #convert to Q(name='apple') | Q(name='bar') | Q(age='apple') | ...
        query_condition = reduce(operator.or_, [Q(**{c:v}) for c in search_columns for v in search_term_list])

        queryset = self.model.objects.filter(query_condition)
        # NOTICE, if you want to use the query before
        # queryset = queryset.filter(query_condition)
        return queryset, use_distinct

So I have been using the code from WeizhongTu’s answer and found a not-so-obvious error in it. When we try to use both filtering and searching with this code, filtering is shadowed by this line:

queryset = self.model.objects.filter(eval(query_condition))

It is important to use the previous results ONLY. So you must never use self.model.objects to obtain the queryset, but only filter the queryset itself. Like this:

def get_search_results(self, request, queryset, search_term):
    # search_term is what you input in admin site
    # queryset is the list of objects passed to you
    # by the previous functions, e. g. filtering 
    search_term_list = search_term.split(' ') #['apple','bar']
    search_columns = ('name','age','address')
    # convert to Q(name='apple') | Q(name='bar') | Q(age='apple') | ...
    query_condition = ' | '.join(['Q(%s="%s")'%(x,y) for x in search_term_list for y in search_columns])
    appended_queryset = queryset.filter(eval(query_condition))
    # queryset is search results
    queryset, use_distinct = super(PersonAdmin, self).get_search_results(request, queryset, search_term)
    queryset |= appended_queryset
    return queryset, use_distinct

you can add an ModelAdmin method:

def queryset(self, request):
    qs = super(MyModelAdmin, self).queryset(request)
    # modify queryset here, eg. only user-assigned tasks
    qs.filter(assigned__exact=request.user)
    return qs

you have a request here, so most of the stuff can be view dependent, including url parameters, cookies, sessions etc.