Add support for multiple offline contexts.

Offline compression now supports generation for multiple contexts by
providing a list or tuple of dictionaries, or by providing a dotted
string pointing to a generator function.

This makes it easier to generate multiple contexts dynamically for
situations where a user might be able to select or be served a different
theme for a website, etc.

AUTHORS

@@ -70,6 +70,7 @@ Matthew Tretter
 Mehmet S. Catalbas
 Michael van de Waeter
 Mike Yumatov
+Nick Pope
 Nicolas Charlot
 Niran Babalola
 Paul McMillan

compressor/management/commands/compress.py

@@ -22,6 +22,7 @@ from compressor.conf import settings
 from compressor.exceptions import (OfflineGenerationError, TemplateSyntaxError,
                                    TemplateDoesNotExist)
 from compressor.templatetags.compress import CompressorNode
+from compressor.utils import get_mod_func
 
 if six.PY3:
     # there is an 'io' module in python 2.6+, but io.StringIO does not
@@ -211,11 +212,25 @@ class Command(NoArgsCommand):
                       "\n\t".join((t.template_name
                                    for t in compressor_nodes.keys())) + "\n")
 
+        contexts = settings.COMPRESS_OFFLINE_CONTEXT
+        if isinstance(contexts, six.string_types):
+            try:
+                module, function = get_mod_func(contexts)
+                contexts = getattr(import_module(module), function)()
+            except (AttributeError, ImportError, TypeError) as e:
+                raise ImportError("Couldn't import offline context function %s: %s" %
+                                  (settings.COMPRESS_OFFLINE_CONTEXT, e))
+        elif not isinstance(contexts, (list, tuple)):
+            contexts = [contexts]
+
         log.write("Compressing... ")
-        count = 0
+        block_count = context_count = 0
         results = []
         offline_manifest = SortedDict()
-        init_context = parser.get_init_context(settings.COMPRESS_OFFLINE_CONTEXT)
+
+        for context_dict in contexts:
+            context_count += 1
+            init_context = parser.get_init_context(context_dict)
 
             for template, nodes in compressor_nodes.items():
                 context = Context(init_context)
@@ -242,13 +257,13 @@ class Command(NoArgsCommand):
                     offline_manifest[key] = result
                     context.pop()
                     results.append(result)
-                count += 1
+                    block_count += 1
 
         write_offline_manifest(offline_manifest)
 
-        log.write("done\nCompressed %d block(s) from %d template(s).\n" %
+        log.write("done\nCompressed %d block(s) from %d template(s) for %d context(s).\n" %
-                  (count, len(compressor_nodes)))
+                  (block_count, len(compressor_nodes), context_count))
-        return count, results
+        return block_count, results
 
     def handle_extensions(self, extensions=('html',)):
         """

compressor/tests/test_offline.py

@@ -8,12 +8,14 @@ from django.core.management.base import CommandError
 from django.template import Template, Context
 from django.test import TestCase
 from django.utils import six, unittest
+from django.utils.importlib import import_module
 
 from compressor.cache import flush_offline_manifest, get_offline_manifest
 from compressor.conf import settings
 from compressor.exceptions import OfflineGenerationError
 from compressor.management.commands.compress import Command as CompressCommand
 from compressor.storage import default_storage
+from compressor.utils import get_mod_func
 
 if six.PY3:
     # there is an 'io' module in python 2.6+, but io.StringIO does not
@@ -32,6 +34,11 @@ else:
 _TEST_JINJA2 = not(sys.version_info[0] == 3 and sys.version_info[1] == 2)
 
 
+def offline_context_generator():
+    for i in range(1, 4):
+        yield {'content': 'OK %d!' % i}
+
+
 class OfflineTestCaseMixin(object):
     template_name = "test_compressor_offline.html"
     verbosity = 0
@@ -88,22 +95,30 @@ class OfflineTestCaseMixin(object):
         if default_storage.exists(manifest_path):
             default_storage.delete(manifest_path)
 
+    def _prepare_contexts(self, engine):
+        if engine == 'django':
+            return [Context(settings.COMPRESS_OFFLINE_CONTEXT)]
+        if engine == 'jinja2':
+            return [settings.COMPRESS_OFFLINE_CONTEXT]
+        return None
+
     def _render_template(self, engine):
-        if engine == "django":
+        contexts = self._prepare_contexts(engine)
-            return self.template.render(Context(settings.COMPRESS_OFFLINE_CONTEXT))
+        if engine == 'django':
-        elif engine == "jinja2":
+            return ''.join(self.template.render(c) for c in contexts)
-            return self.template_jinja2.render(settings.COMPRESS_OFFLINE_CONTEXT) + "\n"
+        if engine == 'jinja2':
-        else:
+            return '\n'.join(self.template_jinja2.render(c) for c in contexts) + "\n"
         return None
 
     def _test_offline(self, engine):
+        hashes = self.expected_hash
+        if not isinstance(hashes, (list, tuple)):
+            hashes = [hashes]
         count, result = CompressCommand().compress(log=self.log, verbosity=self.verbosity, engine=engine)
-        self.assertEqual(1, count)
+        self.assertEqual(len(hashes), count)
-        self.assertEqual([
+        self.assertEqual(['<script type="text/javascript" src="/static/CACHE/js/%s.js"></script>' % h for h in hashes], result)
-            '<script type="text/javascript" src="/static/CACHE/js/%s.js"></script>' % (self.expected_hash, ),
-        ], result)
         rendered_template = self._render_template(engine)
-        self.assertEqual(rendered_template, "".join(result) + "\n")
+        self.assertEqual(rendered_template, '\n'.join(result) + '\n')
 
     def test_offline(self):
         for engine in self.engines:
@@ -247,6 +262,84 @@ class OfflineGenerationTestCaseWithContext(OfflineTestCaseMixin, TestCase):
         super(OfflineGenerationTestCaseWithContext, self).tearDown()
 
 
+class OfflineGenerationTestCaseWithContextList(OfflineTestCaseMixin, TestCase):
+    templates_dir = 'test_with_context'
+    expected_hash = ['f8bcaea049b3', 'db12749b1e80', 'e9f4a0054a06']
+
+    def setUp(self):
+        self.old_offline_context = settings.COMPRESS_OFFLINE_CONTEXT
+        settings.COMPRESS_OFFLINE_CONTEXT = [{'content': 'OK %d!' % i} for i in range(1, 4)]
+        super(OfflineGenerationTestCaseWithContextList, self).setUp()
+
+    def tearDown(self):
+        settings.COMPRESS_OFFLINE_CONTEXT = self.old_offline_context
+        super(OfflineGenerationTestCaseWithContextList, self).tearDown()
+
+    def _prepare_contexts(self, engine):
+        if engine == 'django':
+            return [Context(c) for c in settings.COMPRESS_OFFLINE_CONTEXT]
+        if engine == 'jinja2':
+            return settings.COMPRESS_OFFLINE_CONTEXT
+        return None
+
+
+class OfflineGenerationTestCaseWithContextGenerator(OfflineTestCaseMixin, TestCase):
+    templates_dir = 'test_with_context'
+    expected_hash = ['f8bcaea049b3', 'db12749b1e80', 'e9f4a0054a06']
+
+    def setUp(self):
+        self.old_offline_context = settings.COMPRESS_OFFLINE_CONTEXT
+        settings.COMPRESS_OFFLINE_CONTEXT = 'compressor.tests.test_offline.offline_context_generator'
+        super(OfflineGenerationTestCaseWithContextGenerator, self).setUp()
+
+    def tearDown(self):
+        settings.COMPRESS_OFFLINE_CONTEXT = self.old_offline_context
+        super(OfflineGenerationTestCaseWithContextGenerator, self).tearDown()
+
+    def _prepare_contexts(self, engine):
+        module, function = get_mod_func(settings.COMPRESS_OFFLINE_CONTEXT)
+        contexts = getattr(import_module(module), function)()
+        if engine == 'django':
+            return (Context(c) for c in contexts)
+        if engine == 'jinja2':
+            return contexts
+        return None
+
+
+class OfflineGenerationTestCaseWithContextGeneratorImportError(OfflineTestCaseMixin, TestCase):
+    templates_dir = 'test_with_context'
+
+    def _test_offline(self, engine):
+        old_offline_context = settings.COMPRESS_OFFLINE_CONTEXT
+
+        try:
+            # Path with invalid module name -- ImportError:
+            settings.COMPRESS_OFFLINE_CONTEXT = 'invalid_module.invalid_function'
+            self.assertRaises(ImportError, CompressCommand().compress, engine=engine)
+
+            # Module name only without function -- AttributeError:
+            settings.COMPRESS_OFFLINE_CONTEXT = 'compressor'
+            self.assertRaises(ImportError, CompressCommand().compress, engine=engine)
+
+            # Path with invalid function name -- AttributeError:
+            settings.COMPRESS_OFFLINE_CONTEXT = 'compressor.tests.invalid_function'
+            self.assertRaises(ImportError, CompressCommand().compress, engine=engine)
+
+            # Path without function attempts call on module -- TypeError:
+            settings.COMPRESS_OFFLINE_CONTEXT = 'compressor.tests.test_offline'
+            self.assertRaises(ImportError, CompressCommand().compress, engine=engine)
+
+            # Valid path to generator function -- no ImportError:
+            settings.COMPRESS_OFFLINE_CONTEXT = 'compressor.tests.test_offline.offline_context_generator'
+            try:
+                CompressCommand().compress(engine=engine)
+            except ImportError:
+                self.fail("Valid path to offline context generator mustn't raise ImportError.")
+
+        finally:
+            settings.COMPRESS_OFFLINE_CONTEXT = old_offline_context
+
+
 class OfflineGenerationTestCaseErrors(OfflineTestCaseMixin, TestCase):
     templates_dir = "test_error_handling"
 

docs/settings.txt

@@ -492,6 +492,37 @@ Offline settings
 
     If available, the ``STATIC_URL`` setting is also added to the context.
 
+    .. note::
+
+        It is also possible to perform offline compression for multiple
+        contexts by providing a list or tuple of dictionaries, or by providing
+        a dotted string pointing to a generator function.
+
+        This makes it easier to generate contexts dynamically for situations
+        where a user might be able to select a different theme in their user
+        profile, or be served different stylesheets based on other criteria.
+
+        An example of multiple offline contexts by providing a list or tuple::
+
+            # project/settings.py:
+            COMPRESS_OFFLINE_CONTEXT = [
+                {'THEME': 'plain', 'STATIC_URL': STATIC_URL},
+                {'THEME': 'fancy', 'STATIC_URL': STATIC_URL},
+                # ...
+            ]
+
+        An example of multiple offline contexts generated dynamically::
+
+            # project/settings.py:
+            COMPRESS_OFFLINE_CONTEXT = 'project.module.offline_context'
+
+            # project/module.py:
+            from django.conf import settings
+            def offline_context():
+                from project.models import Company
+                for theme in set(Company.objects.values_list('theme', flat=True)):
+                    yield {'THEME': theme, 'STATIC_URL': settings.STATIC_URL}
+
 .. attribute:: COMPRESS_OFFLINE_MANIFEST
 
     :Default: ``manifest.json``