Merge pull request #780 from MITx/feature/cdodge/cms-static-content-management

Feature/cdodge/cms static content management

common/lib/xmodule/xmodule/capa_module.py

@@ -10,6 +10,7 @@ import sys
 
 from datetime import timedelta
 from lxml import etree
+from lxml.html import rewrite_links
 from pkg_resources import resource_string
 
 from capa.capa_problem import LoncapaProblem
@@ -332,6 +333,15 @@ class CapaModule(XModule):
             html = '<div id="problem_{id}" class="problem" data-url="{ajax_url}">'.format(
                 id=self.location.html_id(), ajax_url=self.system.ajax_url) + html + "</div>"
 
+        # cdodge: OK, we have to do two rounds of url reference subsitutions
+        # one which uses the 'asset library' that is served by the contentstore and the
+        # more global /static/ filesystem based static content.
+        # NOTE: rewrite_content_links is defined in XModule
+        # This is a bit unfortunate and I'm sure we'll try to considate this into
+        # a one step process.
+        html = rewrite_links(html, self.rewrite_content_links)
+
+        # now do the substitutions which are filesystem based, e.g. '/static/' prefixes
         return self.system.replace_urls(html, self.metadata['data_dir'])
 
     def handle_ajax(self, dispatch, get):

common/lib/xmodule/xmodule/contentstore/content.py

@@ -0,0 +1,26 @@
+XASSET_LOCATION_TAG = 'c4x'
+XASSET_SRCREF_PREFIX = 'xasset:'
+
+class StaticContent(object):
+    def __init__(self, filename, name, content_type, data, last_modified_at=None):
+        self.filename = filename
+        self.name = name
+        self.content_type = content_type
+        self.data = data
+        self.last_modified_at = last_modified_at
+
+    @staticmethod
+    def compute_location_filename(org, course, name):
+        return '/{0}/{1}/{2}/asset/{3}'.format(XASSET_LOCATION_TAG, org, course, name)
+
+'''
+Abstraction for all ContentStore providers (e.g. MongoDB)
+'''
+class ContentStore(object):
+    def save(self, content):
+        raise NotImplementedError
+
+    def find(self, filename):
+        raise NotImplementedError
+
+            

common/lib/xmodule/xmodule/contentstore/django.py

@@ -0,0 +1,29 @@
+from __future__ import absolute_import
+from importlib import import_module
+from os import environ
+
+from django.conf import settings
+
+_CONTENTSTORE = None
+
+def load_function(path):
+    """
+    Load a function by name.
+
+    path is a string of the form "path.to.module.function"
+    returns the imported python object `function` from `path.to.module`
+    """
+    module_path, _, name = path.rpartition('.')
+    return getattr(import_module(module_path), name)
+
+
+def contentstore():
+    global _CONTENTSTORE
+
+    if _CONTENTSTORE is None:
+        class_ = load_function(settings.CONTENTSTORE['ENGINE'])
+        options = {}
+        options.update(settings.CONTENTSTORE['OPTIONS'])
+        _CONTENTSTORE = class_(**options)
+
+    return _CONTENTSTORE

common/lib/xmodule/xmodule/contentstore/mongo.py

@@ -0,0 +1,32 @@
+from pymongo import Connection
+import gridfs
+from gridfs.errors import NoFile
+
+import sys
+import logging
+
+from .content import StaticContent, ContentStore
+from xmodule.exceptions import NotFoundError
+
+
+class MongoContentStore(ContentStore):
+    def __init__(self, host, db, port=27017):
+        logging.debug( 'Using MongoDB for static content serving at host={0} db={1}'.format(host,db))
+        _db = Connection(host=host, port=port)[db]
+        self.fs = gridfs.GridFS(_db)
+
+    def save(self, content):
+        with self.fs.new_file(filename=content.filename, content_type=content.content_type, displayname=content.name) as fp:
+            fp.write(content.data)
+            return content
+        
+    
+    def find(self, filename):
+        try:
+            with self.fs.get_last_version(filename) as fp:
+                return StaticContent(fp.filename, fp.displayname, fp.content_type, fp.read(), fp.uploadDate)
+        except NoFile:
+            raise NotFoundError()
+
+
+        

common/lib/xmodule/xmodule/html_module.py

@@ -4,6 +4,7 @@ import logging
 import os
 import sys
 from lxml import etree
+from lxml.html import rewrite_links
 from path import path
 
 from .x_module import XModule
@@ -12,6 +13,9 @@ from .xml_module import XmlDescriptor, name_to_pathname
 from .editing_module import EditingDescriptor
 from .stringify import stringify_children
 from .html_checker import check_html
+from xmodule.modulestore import Location
+
+from xmodule.contentstore.content import XASSET_SRCREF_PREFIX, StaticContent
 
 log = logging.getLogger("mitx.courseware")
 
@@ -21,7 +25,8 @@ class HtmlModule(XModule):
     js_module_name = "HTMLModule"
     
     def get_html(self):
-        return self.html
+        # cdodge: perform link substitutions for any references to course static content (e.g. images)
+        return rewrite_links(self.html, self.rewrite_content_links)
 
     def __init__(self, system, location, definition, descriptor,
                  instance_state=None, shared_state=None, **kwargs):
@@ -30,6 +35,7 @@ class HtmlModule(XModule):
         self.html = self.definition['data']
 
 
+
 class HtmlDescriptor(XmlDescriptor, EditingDescriptor):
     """
     Module for putting raw html in a course

common/lib/xmodule/xmodule/x_module.py

@@ -12,6 +12,8 @@ from pkg_resources import resource_listdir, resource_string, resource_isdir
 from xmodule.modulestore import Location
 from xmodule.timeparse import parse_time
 
+from xmodule.contentstore.content import StaticContent, XASSET_SRCREF_PREFIX
+
 log = logging.getLogger('mitx.' + __name__)
 
 
@@ -317,6 +319,20 @@ class XModule(HTMLSnippet):
             get is a dictionary-like object '''
         return ""
 
+    # cdodge: added to support dynamic substitutions of 
+    # links for courseware assets (e.g. images). <link> is passed through from lxml.html parser
+    def rewrite_content_links(self, link):
+        # see if we start with our format, e.g. 'xasset:<filename>'
+        if link.startswith(XASSET_SRCREF_PREFIX):
+            # yes, then parse out the name
+            name = link[len(XASSET_SRCREF_PREFIX):]
+            loc = Location(self.location)
+            # resolve the reference to our internal 'filepath' which
+            link = StaticContent.compute_location_filename(loc.org, loc.course, name)
+
+        return link
+
+
 
 def policy_key(location):
     """