Code layout change.

[wolnelektury.git] / src / api / emitters.py

diff --git a/src/api/emitters.py b/src/api/emitters.py
new file mode 100644 (file)
index 0000000..2f6f7e7
--- /dev/null
+++ b/src/api/emitters.py
@@ -0,0 +1,70 @@
+# -*- coding: utf-8 -*-
+# This file is part of Wolnelektury, licensed under GNU Affero GPLv3 or later.
+# Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
+#
+"""
+Wrappers for piston Emitter classes.
+
+When outputting a queryset of selected models, instead of returning
+XML or JSON stanzas, SSI include statements are returned.
+
+"""
+from django.core.urlresolvers import reverse
+from django.db.models.query import QuerySet
+from piston.emitters import Emitter, XMLEmitter, JSONEmitter
+from catalogue.models import Book, Fragment, Tag
+from django.utils.translation import get_language
+
+
+class SsiQS(object):
+    """A wrapper for QuerySet that won't serialize."""
+
+    def __init__(self, queryset):
+        self.queryset = queryset
+
+    def __unicode__(self):
+        raise TypeError("This is not serializable.")
+
+    def get_ssis(self, emitter_format):
+        """Yields SSI include statements for the queryset."""
+        url_pattern = reverse('api_include',
+                kwargs={'model': self.queryset.model.__name__.lower(),
+                    'pk': '0000',
+                    'emitter_format': emitter_format,
+                    'lang': get_language(),
+                    })
+        for instance in self.queryset:
+            yield "<!--#include file='%s'-->" % url_pattern.replace('0000',
+                    str(instance.pk))
+
+
+class SsiEmitterMixin(object):
+    def construct(self):
+        if isinstance(self.data, QuerySet) and self.data.model in (Book,
+                Fragment, Tag):
+            return SsiQS(self.data)
+        else:
+            return super(SsiEmitterMixin, self).construct()
+
+
+class SsiJsonEmitter(SsiEmitterMixin, JSONEmitter):
+    def render(self, request):
+        try:
+            return super(SsiJsonEmitter, self).render(request)
+        except TypeError:
+            return '[%s]' % ",".join(self.construct().get_ssis('json'))
+
+Emitter.register('json', SsiJsonEmitter, 'application/json; charset=utf-8')
+
+
+class SsiXmlEmitter(SsiEmitterMixin, XMLEmitter):
+    def render(self, request):
+        try:
+            return super(SsiXmlEmitter, self).render(request)
+        except TypeError:
+            return '<?xml version="1.0" encoding="utf-8"?>\n' \
+                '<response><resource>%s</resource></response>' % \
+                '</resource><resource>'.join(self.construct().get_ssis('xml'))
+
+Emitter.register('xml', SsiXmlEmitter, 'text/xml; charset=utf-8')
+