Djangoで dataTables.js を使うためのクエリパーザ

datatables.py

# coding: utf-8
"""dataTables.js 用のクエリパーザ
"""
import re

class DataTablesQueryParser(object):
    """dataTables.js 用のクエリパーザ
    """

    def __init__(self, request, column_map=dict(), method='POST'):
        """しょきか
        """
        self.column_map = column_map
        params = dict(getattr(request, method))
        js_boolean = lambda s: dict(true=True, false=False).get(s, False)
        self.draw = int(params.pop('draw', 0)[0])
        self.start = int(params.pop('start', 0)[0])
        self.length = int(params.pop('length', 0)[0])
        self.search_value = params.pop('search[value]', [''])[0]
        self.search_regex = js_boolean(params.pop('search[regex]', '')[0])
        self.columns = {}
        self.order = {}
        for key, value in params.items():
            value = value[0]
            for param, attr, datatype in (
                ('columns', 'data', str),
                ('columns', 'name', str),
                ('columns', 'searchable', js_boolean),
                ('columns', 'orderable', js_boolean),
                ('order', 'column', int),
                ('order', 'dir', str)):
                pattern = r'^(?P<param>%s)\[(?P<index>\d+)\]\[(?P<attr>%s)\]$' %(param, attr)
                match = re.match(pattern, key)
                if match:
                    captured = match.groupdict()
                    index = int(captured['index'])
                    attrs_for_index = getattr(self, param).setdefault(index, {})
                    attrs_for_index[attr] = datatype(value)

    def interpret_field(self, field):
        """サブクラスでオーバライドする。リストを返すので注意。
        """
        return self.column_map.get(field, [field])

    def get_order_by_fields(self):
        """.order_by に使うフィールドのリストを返す
        """
        fields = []
        for column_index in sorted(self.order.keys()):
            prefix = ''
            if self.order[column_index].get('dir', 'asc')=='desc':
                prefix='-'
            fields.extend(
                prefix+field
                for field in self.interpret_field(
                    self.columns[self.order[column_index]['column']]['data']))
        return fields

    def get_search_fields(self):
        """検索用の Q に使うフィールドのリストを返す
        """
        fields = []
        for column_index in sorted(self.columns.keys()):
            if self.columns[column_index].get('searchable', True):
                fields.extend(
                    self.interpret_field(self.columns[column_index]['data']))
        return fields

view.py

from my_app.models import MyModel
from django.db.models import Q

def my_view(request):
    queryset = MyModel.objects.all()
    qs_tuned = queryset.all()
    dt_parser = DataTablesQueryParser(request)
    if dt_parser.search_value:
        q_obj = Q()
        for field in dt_parser.get_search_fields():
            q_obj |= Q(**{field+'__contains': dt_parser.search_value })
        qs_tuned = qs_tuned.filter(Q)
    order_fields = dt_parser.get_order_by_fields()
    if order_fields:
        qs_tuned = qs_tuned.order_by(*order_fields)
    qs_tuned_slice = qs_tuned[dt_parser.start:dt_parser.start+dt_parser.length]
    json_src = dict(
        draw=dt_parser.draw,
        recordsTotal=queryset.count(),
        recordsFiltered=qs_tuned.count(),
        data=[dict(foo=obj.foo, bar=obj.get_bar_display()) for obj in qs_tuned_slice])
    return HttpResponse(json.dumps(json_src), content_type='text/json')