Login

Render Decorator

Author:
dahool
Posted:
September 17, 2009
Language:
Python
Version:
1.1
Score:
2 (after 2 ratings)

Simple decorator to render an html template or return a json response. The view must return a dict object.

Usage example:

@render('page.html')
def a_view(request):
    #do something
    return {'key': 'value'}
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
from django.http import HttpResponse
from django.shortcuts import render_to_response
from django.template import RequestContext
from django.conf import settings

class render:
    '''Register response engines based on HTTP_ACCEPT
     
     parameters:
         template: template for html rendering
         format: supported formats ('json','html')
         
     @render('index.html')
     def my_view(request)

     @render('index.html', ('json',))
     def my_view(request)
          
    html format is supported by default if a template is defined.
    
     @render('json')
     def my_view(request)
    
    in above case, json is the default format.
    
    '''
    class render_decorator:
        
        def __init__(self, parent, view_func):
            self.parent = parent
            self.view_func = view_func
        
        def __call__(self, *args, **kwargs):
            request = args[0]    
            context = self.view_func(*args, **kwargs)

            if isinstance(context, HttpResponse):
                return context
            
            engine = None
            
            if request.META.has_key('HTTP_ACCEPT'):
                accept = request.META['HTTP_ACCEPT']
                for content in self.parent.engines.iterkeys():
                    if accept.find(content)<>-1:
                        engine, template = self.parent.engines.get(content) 
                        break
            
            if engine is None:
                engine, template = self.parent.engines.get(self.parent.default)
            
            cook = context.pop('cookjar',None)

            if 'html'==engine:
                response = self.html_render(request, context, template)
            elif 'json'==engine:
                response = self.json_render(request, context)
            else:
                response = context

            if isinstance(response, HttpResponse):
                if cook:
                    for k,v in cook.iteritems():
                        if v is None:
                            response.delete_cookie(str(k))
                        else:
                            response.set_cookie(str(k), str(v), getattr(settings, 'COMMON_COOKIE_AGE', None))

            return response
            
        def json_render(self,request, context):
            return render_to_json(context)
        
        def html_render(self,request, context, template):
            return render_to_response(
                template, 
                context, 
                context_instance=RequestContext(request),
            )            
    
    def __register_engine(self, engine, template, default = False):
        
        if engine == 'json':
            content_type = 'application/json'
        elif engine == 'html':
            content_type = 'text/html'
        else:
            raise ValueError("Unsuported format %s" % engine)
        
        if default:
            self.default = content_type
        self.engines[content_type] = engine, template
        
    def __init__(self, template=None, format=None):

        self.engines = {}
        
        if format is None:
            format = ()
        elif not isinstance(format, tuple):
            format = (format,)

        if template == 'json':
            self.__register_engine('json', None, True)
        elif template:
            self.__register_engine('html', template, True)
            
        for f in format:
            self.__register_engine(f, None)
            
    def __call__(self, view_func):
        return render.render_decorator(self, view_func)

###### --- RENDER TO JSON --- ######

import time
import datetime
import types
from decimal import *

from django.db import models
from django.utils import simplejson as json
from django.core.serializers.json import DateTimeAwareJSONEncoder
from django.http import HttpResponse

def render_to_json(context):
    resp = []
    for k in context.iterkeys():
        resp.append('"%s": %s' % (k, parse(context[k])))
    data = '{%s}' % ','.join(resp)
    return HttpResponse(data, mimetype='application/json')    
    
def parse(data):
    """
    The main issues with django's default json serializer is that properties that
    had been added to a object dynamically are being ignored (and it also has 
    problems with some models).
    """

    def _any(data):
        ret = None
        if type(data) is types.ListType:
            ret = _list(data)
        elif type(data) is types.DictType:
            ret = _dict(data)
        elif isinstance(data, Decimal):
            # json.dumps() cant handle Decimal
            #ret = str(data)
            ret = float(data)
        elif isinstance(data, models.query.QuerySet):
            # Actually its the same as a list ...
            ret = _list(data)
        elif isinstance(data, models.Model):
            ret = _model(data)
        elif isinstance(data, datetime.date):
            ret = time.strftime("%Y/%m/%d",data.timetuple())
        else:
            ret = data
        return ret
    
    def _model(data):
        ret = {}
        # If we only have a model, we only want to encode the fields.
        for f in data._meta.fields:
            ret[f.attname] = _any(getattr(data, f.attname))
        # And additionally encode arbitrary properties that had been added.
        fields = dir(data.__class__) + ret.keys()
        add_ons = [k for k in dir(data) if k not in fields]
        for k in add_ons:
            ret[k] = _any(getattr(data, k))
        return ret
    
    def _list(data):
        ret = []
        for v in data:
            ret.append(_any(v))
        return ret
    
    def _dict(data):
        ret = {}
        for k,v in data.items():
            ret[k] = _any(v)
        return ret
    
    ret = _any(data)
    
    return json.dumps(ret, cls=DateTimeAwareJSONEncoder)

More like this

  1. Template tag - list punctuation for a list of items by shapiromatron 9 months, 1 week ago
  2. JSONRequestMiddleware adds a .json() method to your HttpRequests by cdcarter 9 months, 2 weeks ago
  3. Serializer factory with Django Rest Framework by julio 1 year, 4 months ago
  4. Image compression before saving the new model / work with JPG, PNG by Schleidens 1 year, 4 months ago
  5. Help text hyperlinks by sa2812 1 year, 5 months ago

Comments

wancharle (on October 2, 2009):

Tranks!

but i have problem in portuguese laguage(pt-br brasil) with render json characters á é í ó ú.

i fix it changing line 187 to return: json.dumps(ret,clss=DateTimeAwareJSONEncoder,ensure_ascii=False,encoding="utf-8")

#

Please login first before commenting.