implemented filter chaining

CHANGELOG.txt

@@ -25,6 +25,7 @@ Changelog
  * Added a system check to warn developers who use a custom Wagtail build but forgot to build the admin css
  * Added success message after updating image from the image upload view (Christian Peters)
  * Added a `request.is_preview` variable for templates to distinguish between previewing and live (Denis Voskvitsov)
+ * Added support for chaining multiple image operations on the `{% image %}` tag (Christian Peters)
  * New translations for Arabic and Latvian
  * 'Pages' link on site stats dashboard now links to the site homepage when only one site exists, rather than the root level
  * Fix: Images and page revisions created by a user are no longer deleted when the user is deleted (Rich Atkinson)

docs/releases/1.3.rst

@@ -71,6 +71,7 @@ Minor features
  * Added success message after updating image from the image upload view (Christian Peters)
  * Added a ``request.is_preview`` variable for templates to distinguish between previewing and live (Denis Voskvitsov)
  * 'Pages' link on site stats dashboard now links to the site homepage when only one site exists, rather than the root level
+ * Added support for chaining multiple image operations on the ``{% image %}`` tag (Christian Peters)
  * New translations for Arabic and Latvian
 
 

wagtail/wagtailimages/models.py

@@ -262,7 +262,7 @@ class AbstractImage(models.Model, TagSearchable):
                 'gif': '.gif',
             }
 
-            output_extension = filter.spec + FORMAT_EXTENSIONS[output_format]
+            output_extension = filter.spec.replace('|', '.') + FORMAT_EXTENSIONS[output_format]
             if cache_key:
                 output_extension = cache_key + '.' + output_extension
 
@@ -360,10 +360,12 @@ def get_image_model():
 
 class Filter(models.Model):
     """
-    Represents an operation that can be applied to an Image to produce a rendition
+    Represents one or more operations that can be applied to an Image to produce a rendition
     appropriate for final display on the website. Usually this would be a resize operation,
     but could potentially involve colour processing, etc.
     """
+
+    # The spec pattern is operation1-var1-var2|operation2-var1
     spec = models.CharField(max_length=255, db_index=True, unique=True)
 
     @cached_property
@@ -373,7 +375,7 @@ class Filter(models.Model):
 
         # Build list of operation objects
         operations = []
-        for op_spec in self.spec.split():
+        for op_spec in self.spec.split('|'):
             op_spec_parts = op_spec.split('-')
 
             if op_spec_parts[0] not in self._registered_operations:
@@ -381,7 +383,6 @@ class Filter(models.Model):
 
             op_class = self._registered_operations[op_spec_parts[0]]
             operations.append(op_class(*op_spec_parts))
-
         return operations
 
     def run(self, image, output):

wagtail/wagtailimages/templatetags/wagtailimages_tags.py

@@ -1,3 +1,5 @@
+import re
+
 from django import template
 from django.utils.functional import cached_property
 
@@ -5,33 +7,60 @@ from wagtail.wagtailimages.models import Filter
 from wagtail.wagtailimages.shortcuts import get_rendition_or_not_found
 
 register = template.Library()
+allowed_filter_pattern = re.compile("^[A-Za-z0-9_\-\.]+$")
 
 
 @register.tag(name="image")
 def image(parser, token):
     bits = token.split_contents()[1:]
     image_expr = parser.compile_filter(bits[0])
-    filter_spec = bits[1]
-    bits = bits[2:]
+    bits = bits[1:]
 
-    if len(bits) == 2 and bits[0] == 'as':
-        # token is of the form {% image self.photo max-320x200 as img %}
-        return ImageNode(image_expr, filter_spec, output_var_name=bits[1])
-    else:
-        # token is of the form {% image self.photo max-320x200 %} - all additional tokens
-        # should be kwargs, which become attributes
-        attrs = {}
-        for bit in bits:
+    filter_specs = []
+    attrs = {}
+    output_var_name = None
+
+    as_context = False  # if True, the next bit to be read is the output variable name
+    is_valid = True
+
+    for bit in bits:
+        if bit == 'as':
+            # token is of the form {% image self.photo max-320x200 as img %}
+            as_context = True
+        elif as_context:
+            if output_var_name is None:
+                output_var_name = bit
+            else:
+                # more than one item exists after 'as' - reject as invalid
+                is_valid = False
+        else:
             try:
                 name, value = bit.split('=')
+                attrs[name] = parser.compile_filter(value)  # setup to resolve context variables as value
             except ValueError:
-                raise template.TemplateSyntaxError(
-                    """'image' tag should be of the form {% image self.photo max-320x200
-                    [ custom-attr=\"value\" ... ] %} or {% image self.photo max-320x200 as img %}"""
-                )
-            attrs[name] = parser.compile_filter(value)  # setup to resolve context variables as value
+                if allowed_filter_pattern.match(bit):
+                    filter_specs.append(bit)
+                else:
+                    raise template.TemplateSyntaxError(
+                        "filter specs in 'image' tag may only contain A-Z, a-z, 0-9, dots, hyphens and underscores. "
+                        "(given filter: {})".format(bit)
+                    )
 
-        return ImageNode(image_expr, filter_spec, attrs=attrs)
+    if as_context and output_var_name is None:
+        # context was introduced but no variable given ...
+        is_valid = False
+
+    if output_var_name and attrs:
+        # attributes are not valid when using the 'as img' form of the tag
+        is_valid = False
+
+    if is_valid:
+        return ImageNode(image_expr, '|'.join(filter_specs), attrs=attrs, output_var_name=output_var_name)
+    else:
+        raise template.TemplateSyntaxError(
+            "'image' tag should be of the form {% image self.photo max-320x200 [ custom-attr=\"value\" ... ] %} "
+            "or {% image self.photo max-320x200 as img %}"
+        )
 
 
 class ImageNode(template.Node):

wagtail/wagtailimages/tests/test_image_operations.py

@@ -1,8 +1,13 @@
 import unittest
 
+from mock import Mock
+
+from django.utils.six import BytesIO
+from wagtail.wagtailcore import hooks
 from wagtail.wagtailimages import image_operations
 from wagtail.wagtailimages.exceptions import InvalidFilterSpecError
 from wagtail.wagtailimages.models import Image, Filter
+from wagtail.wagtailimages.tests.utils import get_test_image_file
 
 
 class WillowOperationRecorder(object):
@@ -378,3 +383,28 @@ class TestCacheKey(unittest.TestCase):
         cache_key = fil.get_cache_key(image)
 
         self.assertEqual(cache_key, '0bbe3b2f')
+
+
+class TestFilter(unittest.TestCase):
+
+    operation_instance = Mock()
+
+    def test_runs_operations(self):
+        self.operation_instance.run = Mock()
+
+        fil = Filter(spec='operation1|operation2')
+        image = Image.objects.create(
+            title="Test image",
+            file=get_test_image_file(),
+        )
+        fil.run(image, BytesIO())
+
+        self.assertEqual(self.operation_instance.run.call_count, 2)
+
+
+@hooks.register('register_image_operations')
+def register_image_operations():
+    return [
+        ('operation1', Mock(return_value=TestFilter.operation_instance)),
+        ('operation2', Mock(return_value=TestFilter.operation_instance))
+    ]

wagtail/wagtailimages/tests/tests.py

@@ -90,6 +90,27 @@ class TestImageTag(TestCase):
         self.assertTrue('width="400"' in result)
         self.assertTrue('height="300"' in result)
 
+    def test_image_tag_with_chained_filters(self):
+        result = self.render_image_tag(self.image, 'fill-200x200 height-150')
+        self.assertTrue('width="150"' in result)
+        self.assertTrue('height="150"' in result)
+
+    def test_filter_specs_must_match_allowed_pattern(self):
+        with self.assertRaises(template.TemplateSyntaxError):
+            self.render_image_tag(self.image, 'fill-200x200|height-150')
+
+        with self.assertRaises(template.TemplateSyntaxError):
+            self.render_image_tag(self.image, 'fill-800x600 alt"test"')
+
+    def test_context_may_only_contain_one_argument(self):
+        with self.assertRaises(template.TemplateSyntaxError):
+            temp = template.Template(
+                '{% load wagtailimages_tags %}{% image image_obj fill-200x200'
+                ' as test_img this_one_should_not_be_there %}<img {{ test_img.attrs }} />'
+            )
+            context = template.Context({'image_obj': self.image})
+            temp.render(context)
+
 
 class TestMissingImage(TestCase):
     """
@@ -393,6 +414,18 @@ class TestRenditionFilenames(TestCase):
 
         self.assertEqual(rendition.file.name, 'images/test_rf3.15ee4958.fill-100x100.png')
 
+    def test_filter_with_pipe_gets_dotted(self):
+        image = Image.objects.create(
+            title="Test image",
+            file=get_test_image_file(filename='test_rf4.png'),
+        )
+        image.set_focal_point(Rect(100, 100, 200, 200))
+        image.save()
+
+        rendition = image.get_rendition('fill-200x200|height-150')
+
+        self.assertEqual(rendition.file.name, 'images/test_rf4.15ee4958.fill-200x200.height-150.png')
+
 
 class TestDifferentUpload(TestCase):
     def test_upload_path(self):