X-Git-Url: https://git.mdrn.pl/wolnelektury.git/blobdiff_plain/d0ab1d8908cadac9f51a17e2fe9e1193f14e28cc..0e87ae0739ed3e72301b7b718098f97a7f06a5d8:/apps/piston/emitters.py

diff --git a/apps/piston/emitters.py b/apps/piston/emitters.py
new file mode 100644
index 000000000..1ff0a52da
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+++ b/apps/piston/emitters.py
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+from __future__ import generators
+
+import decimal, re, inspect
+import copy
+
+try:
+    # yaml isn't standard with python.  It shouldn't be required if it
+    # isn't used.
+    import yaml
+except ImportError:
+    yaml = None
+
+# Fallback since `any` isn't in Python <2.5
+try:
+    any
+except NameError:
+    def any(iterable):
+        for element in iterable:
+            if element:
+                return True
+        return False
+
+from django.db.models.query import QuerySet
+from django.db.models import Model, permalink
+from django.utils import simplejson
+from django.utils.xmlutils import SimplerXMLGenerator
+from django.utils.encoding import smart_unicode
+from django.core.urlresolvers import reverse, NoReverseMatch
+from django.core.serializers.json import DateTimeAwareJSONEncoder
+from django.http import HttpResponse
+from django.core import serializers
+
+from utils import HttpStatusCode, Mimer
+
+try:
+    import cStringIO as StringIO
+except ImportError:
+    import StringIO
+
+try:
+    import cPickle as pickle
+except ImportError:
+    import pickle
+
+# Allow people to change the reverser (default `permalink`).
+reverser = permalink
+
+class Emitter(object):
+    """
+    Super emitter. All other emitters should subclass
+    this one. It has the `construct` method which
+    conveniently returns a serialized `dict`. This is
+    usually the only method you want to use in your
+    emitter. See below for examples.
+
+    `RESERVED_FIELDS` was introduced when better resource
+    method detection came, and we accidentially caught these
+    as the methods on the handler. Issue58 says that's no good.
+    """
+    EMITTERS = { }
+    RESERVED_FIELDS = set([ 'read', 'update', 'create', 
+                            'delete', 'model', 'anonymous',
+                            'allowed_methods', 'fields', 'exclude' ])
+
+    def __init__(self, payload, typemapper, handler, fields=(), anonymous=True):
+        self.typemapper = typemapper
+        self.data = payload
+        self.handler = handler
+        self.fields = fields
+        self.anonymous = anonymous
+        
+        if isinstance(self.data, Exception):
+            raise
+    
+    def method_fields(self, handler, fields):
+        if not handler:
+            return { }
+
+        ret = dict()
+            
+        for field in fields - Emitter.RESERVED_FIELDS:
+            t = getattr(handler, str(field), None)
+
+            if t and callable(t):
+                ret[field] = t
+
+        return ret
+    
+    def construct(self):
+        """
+        Recursively serialize a lot of types, and
+        in cases where it doesn't recognize the type,
+        it will fall back to Django's `smart_unicode`.
+        
+        Returns `dict`.
+        """
+        def _any(thing, fields=()):
+            """
+            Dispatch, all types are routed through here.
+            """
+            ret = None
+            
+            if isinstance(thing, QuerySet):
+                ret = _qs(thing, fields=fields)
+            elif isinstance(thing, (tuple, list)):
+                ret = _list(thing)
+            elif isinstance(thing, dict):
+                ret = _dict(thing)
+            elif isinstance(thing, decimal.Decimal):
+                ret = str(thing)
+            elif isinstance(thing, Model):
+                ret = _model(thing, fields=fields)
+            elif isinstance(thing, HttpResponse):
+                raise HttpStatusCode(thing)
+            elif inspect.isfunction(thing):
+                if not inspect.getargspec(thing)[0]:
+                    ret = _any(thing())
+            elif hasattr(thing, '__emittable__'):
+                f = thing.__emittable__
+                if inspect.ismethod(f) and len(inspect.getargspec(f)[0]) == 1:
+                    ret = _any(f())
+            elif repr(thing).startswith("<django.db.models.fields.related.RelatedManager"):
+                ret = _any(thing.all())
+            else:
+                ret = smart_unicode(thing, strings_only=True)
+
+            return ret
+
+        def _fk(data, field):
+            """
+            Foreign keys.
+            """
+            return _any(getattr(data, field.name))
+        
+        def _related(data, fields=()):
+            """
+            Foreign keys.
+            """
+            return [ _model(m, fields) for m in data.iterator() ]
+        
+        def _m2m(data, field, fields=()):
+            """
+            Many to many (re-route to `_model`.)
+            """
+            return [ _model(m, fields) for m in getattr(data, field.name).iterator() ]
+        
+        def _model(data, fields=()):
+            """
+            Models. Will respect the `fields` and/or
+            `exclude` on the handler (see `typemapper`.)
+            """
+            ret = { }
+            handler = self.in_typemapper(type(data), self.anonymous)
+            get_absolute_uri = False
+            
+            if handler or fields:
+                v = lambda f: getattr(data, f.attname)
+
+                if not fields:
+                    """
+                    Fields was not specified, try to find teh correct
+                    version in the typemapper we were sent.
+                    """
+                    mapped = self.in_typemapper(type(data), self.anonymous)
+                    get_fields = set(mapped.fields)
+                    exclude_fields = set(mapped.exclude).difference(get_fields)
+
+                    if 'absolute_uri' in get_fields:
+                        get_absolute_uri = True
+                
+                    if not get_fields:
+                        get_fields = set([ f.attname.replace("_id", "", 1)
+                            for f in data._meta.fields ])
+                
+                    # sets can be negated.
+                    for exclude in exclude_fields:
+                        if isinstance(exclude, basestring):
+                            get_fields.discard(exclude)
+                            
+                        elif isinstance(exclude, re._pattern_type):
+                            for field in get_fields.copy():
+                                if exclude.match(field):
+                                    get_fields.discard(field)
+                                    
+                else:
+                    get_fields = set(fields)
+
+                met_fields = self.method_fields(handler, get_fields)
+                           
+                for f in data._meta.local_fields:
+                    if f.serialize and not any([ p in met_fields for p in [ f.attname, f.name ]]):
+                        if not f.rel:
+                            if f.attname in get_fields:
+                                ret[f.attname] = _any(v(f))
+                                get_fields.remove(f.attname)
+                        else:
+                            if f.attname[:-3] in get_fields:
+                                ret[f.name] = _fk(data, f)
+                                get_fields.remove(f.name)
+                
+                for mf in data._meta.many_to_many:
+                    if mf.serialize and mf.attname not in met_fields:
+                        if mf.attname in get_fields:
+                            ret[mf.name] = _m2m(data, mf)
+                            get_fields.remove(mf.name)
+                
+                # try to get the remainder of fields
+                for maybe_field in get_fields:
+                    if isinstance(maybe_field, (list, tuple)):
+                        model, fields = maybe_field
+                        inst = getattr(data, model, None)
+
+                        if inst:
+                            if hasattr(inst, 'all'):
+                                ret[model] = _related(inst, fields)
+                            elif callable(inst):
+                                if len(inspect.getargspec(inst)[0]) == 1:
+                                    ret[model] = _any(inst(), fields)
+                            else:
+                                ret[model] = _model(inst, fields)
+
+                    elif maybe_field in met_fields:
+                        # Overriding normal field which has a "resource method"
+                        # so you can alter the contents of certain fields without
+                        # using different names.
+                        ret[maybe_field] = _any(met_fields[maybe_field](data))
+
+                    else:                    
+                        maybe = getattr(data, maybe_field, None)
+                        if maybe:
+                            if callable(maybe):
+                                if len(inspect.getargspec(maybe)[0]) == 1:
+                                    ret[maybe_field] = _any(maybe())
+                            else:
+                                ret[maybe_field] = _any(maybe)
+                        else:
+                            handler_f = getattr(handler or self.handler, maybe_field, None)
+
+                            if handler_f:
+                                ret[maybe_field] = _any(handler_f(data))
+
+            else:
+                for f in data._meta.fields:
+                    ret[f.attname] = _any(getattr(data, f.attname))
+                
+                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))
+            
+            # resouce uri
+            if self.in_typemapper(type(data), self.anonymous):
+                handler = self.in_typemapper(type(data), self.anonymous)
+                if hasattr(handler, 'resource_uri'):
+                    url_id, fields = handler.resource_uri(data)
+
+                    try:
+                        ret['resource_uri'] = reverser( lambda: (url_id, fields) )()
+                    except NoReverseMatch, e:
+                        pass
+            
+            if hasattr(data, 'get_api_url') and 'resource_uri' not in ret:
+                try: ret['resource_uri'] = data.get_api_url()
+                except: pass
+            
+            # absolute uri
+            if hasattr(data, 'get_absolute_url') and get_absolute_uri:
+                try: ret['absolute_uri'] = data.get_absolute_url()
+                except: pass
+            
+            return ret
+        
+        def _qs(data, fields=()):
+            """
+            Querysets.
+            """
+            return [ _any(v, fields) for v in data ]
+                
+        def _list(data):
+            """
+            Lists.
+            """
+            return [ _any(v) for v in data ]
+            
+        def _dict(data):
+            """
+            Dictionaries.
+            """
+            return dict([ (k, _any(v)) for k, v in data.iteritems() ])
+            
+        # Kickstart the seralizin'.
+        return _any(self.data, self.fields)
+    
+    def in_typemapper(self, model, anonymous):
+        for klass, (km, is_anon) in self.typemapper.iteritems():
+            if model is km and is_anon is anonymous:
+                return klass
+        
+    def render(self):
+        """
+        This super emitter does not implement `render`,
+        this is a job for the specific emitter below.
+        """
+        raise NotImplementedError("Please implement render.")
+        
+    def stream_render(self, request, stream=True):
+        """
+        Tells our patched middleware not to look
+        at the contents, and returns a generator
+        rather than the buffered string. Should be
+        more memory friendly for large datasets.
+        """
+        yield self.render(request)
+        
+    @classmethod
+    def get(cls, format):
+        """
+        Gets an emitter, returns the class and a content-type.
+        """
+        if cls.EMITTERS.has_key(format):
+            return cls.EMITTERS.get(format)
+
+        raise ValueError("No emitters found for type %s" % format)
+    
+    @classmethod
+    def register(cls, name, klass, content_type='text/plain'):
+        """
+        Register an emitter.
+        
+        Parameters::
+         - `name`: The name of the emitter ('json', 'xml', 'yaml', ...)
+         - `klass`: The emitter class.
+         - `content_type`: The content type to serve response as.
+        """
+        cls.EMITTERS[name] = (klass, content_type)
+        
+    @classmethod
+    def unregister(cls, name):
+        """
+        Remove an emitter from the registry. Useful if you don't
+        want to provide output in one of the built-in emitters.
+        """
+        return cls.EMITTERS.pop(name, None)
+    
+class XMLEmitter(Emitter):
+    def _to_xml(self, xml, data):
+        if isinstance(data, (list, tuple)):
+            for item in data:
+                xml.startElement("resource", {})
+                self._to_xml(xml, item)
+                xml.endElement("resource")
+        elif isinstance(data, dict):
+            for key, value in data.iteritems():
+                xml.startElement(key, {})
+                self._to_xml(xml, value)
+                xml.endElement(key)
+        else:
+            xml.characters(smart_unicode(data))
+
+    def render(self, request):
+        stream = StringIO.StringIO()
+        
+        xml = SimplerXMLGenerator(stream, "utf-8")
+        xml.startDocument()
+        xml.startElement("response", {})
+        
+        self._to_xml(xml, self.construct())
+        
+        xml.endElement("response")
+        xml.endDocument()
+        
+        return stream.getvalue()
+
+Emitter.register('xml', XMLEmitter, 'text/xml; charset=utf-8')
+Mimer.register(lambda *a: None, ('text/xml',))
+
+class JSONEmitter(Emitter):
+    """
+    JSON emitter, understands timestamps.
+    """
+    def render(self, request):
+        cb = request.GET.get('callback')
+        seria = simplejson.dumps(self.construct(), cls=DateTimeAwareJSONEncoder, ensure_ascii=False, indent=4)
+
+        # Callback
+        if cb:
+            return '%s(%s)' % (cb, seria)
+
+        return seria
+    
+Emitter.register('json', JSONEmitter, 'application/json; charset=utf-8')
+Mimer.register(simplejson.loads, ('application/json',))
+    
+class YAMLEmitter(Emitter):
+    """
+    YAML emitter, uses `safe_dump` to omit the
+    specific types when outputting to non-Python.
+    """
+    def render(self, request):
+        return yaml.safe_dump(self.construct())
+
+if yaml:  # Only register yaml if it was import successfully.
+    Emitter.register('yaml', YAMLEmitter, 'application/x-yaml; charset=utf-8')
+    Mimer.register(lambda s: dict(yaml.load(s)), ('application/x-yaml',))
+
+class PickleEmitter(Emitter):
+    """
+    Emitter that returns Python pickled.
+    """
+    def render(self, request):
+        return pickle.dumps(self.construct())
+        
+Emitter.register('pickle', PickleEmitter, 'application/python-pickle')
+
+"""
+WARNING: Accepting arbitrary pickled data is a huge security concern.
+The unpickler has been disabled by default now, and if you want to use
+it, please be aware of what implications it will have.
+
+Read more: http://nadiana.com/python-pickle-insecure
+
+Uncomment the line below to enable it. You're doing so at your own risk.
+"""
+# Mimer.register(pickle.loads, ('application/python-pickle',))
+
+class DjangoEmitter(Emitter):
+    """
+    Emitter for the Django serialized format.
+    """
+    def render(self, request, format='xml'):
+        if isinstance(self.data, HttpResponse):
+            return self.data
+        elif isinstance(self.data, (int, str)):
+            response = self.data
+        else:
+            response = serializers.serialize(format, self.data, indent=True)
+
+        return response
+        
+Emitter.register('django', DjangoEmitter, 'text/xml; charset=utf-8')