modelsearch.py

import operator
from django.db.models import Q

def search(model_or_qs, search_fields, search_string):
    """
    Perform a quick and dirty model "search", similar to how the admin's
    `search_fields` works (see http://tinyurl.com/66xz2n)::
    
        >>> search(Entry, ['summary', 'body'], 'content')
        [...]
        
        >>> search(Person.objects.alive(), ['^first_name'], 'J')
        [...]
    """
    if hasattr(model_or_qs, '_default_manager'):
        qs = model_or_qs._default_manager.all()
    else:
        qs = model_or_qs
    
    clauses = []
    for field in search_fields:
        if field.startswith('^'):
            query = '%s__istartswith' % field[1:]
        elif field.startswith('='):
            query = '%s__exact' % field[1:]
        else:
            query = '%s__icontains' % field
        clauses.append(Q(**{query: search_string}))
    
    query = reduce(operator.or_, clauses)
    return qs.filter(query)