Expose send_file max-age as config value, #433.

Need to add the same hook in a Blueprint, but this is the first such
case where we need app.config in the Blueprint.

CHANGES

@@ -48,10 +48,14 @@ Relase date to be decided, codename to be chosen.
 - View functions can now return a tuple with the first instance being an
   instance of :class:`flask.Response`.  This allows for returning
   ``jsonify(error="error msg"), 400`` from a view function.
-- :class:`flask.Flask` now provides a `get_static_file_options` hook for
-  subclasses to override behavior of serving static files through Flask,
-  optionally by filename, which for example allows changing cache controls by
-  file extension.
+- :class:`flask.Flask` now provides a `get_send_file_options` hook for
+  subclasses to override behavior of serving static files from Flask when using
+  :meth:`flask.Flask.send_static_file` based on keywords in
+  :func:`flask.helpers.send_file`.  This hook is provided a filename, which for
+  example allows changing cache controls by file extension.  The default
+  max-age for `send_static_file` can be configured through a new
+  ``SEND_FILE_MAX_AGE_DEFAULT`` configuration variable, regardless of whether
+  the `get_send_file_options` hook is used.
 
 
 Version 0.8.1

docs/config.rst

@@ -107,6 +107,13 @@ The following configuration values are used internally by Flask:
                                   reject incoming requests with a
                                   content length greater than this by
                                   returning a 413 status code.
+``SEND_FILE_MAX_AGE_DEFAULT``:    Default cache control max age to use with
+                                  :meth:`flask.Flask.send_static_file`, in
+                                  seconds. Override this value on a per-file
+                                  basis using the
+                                  :meth:`flask.Flask.get_send_file_options` and
+                                  :meth:`flask.Blueprint.get_send_file_options`
+                                  hooks. Defaults to 43200 (12 hours).
 ``TRAP_HTTP_EXCEPTIONS``          If this is set to ``True`` Flask will
                                   not execute the error handlers of HTTP
                                   exceptions but instead treat the

flask/app.py

@@ -249,6 +249,7 @@ class Flask(_PackageBoundObject):
         'SESSION_COOKIE_HTTPONLY':              True,
         'SESSION_COOKIE_SECURE':                False,
         'MAX_CONTENT_LENGTH':                   None,
+        'SEND_FILE_MAX_AGE_DEFAULT':            12 * 60 * 60, # 12 hours
         'TRAP_BAD_REQUEST_ERRORS':              False,
         'TRAP_HTTP_EXCEPTIONS':                 False
     })
@@ -1020,6 +1021,12 @@ class Flask(_PackageBoundObject):
             self.error_handler_spec.setdefault(key, {}).setdefault(None, []) \
                 .append((code_or_exception, f))
 
+    def get_send_file_options(self, filename):
+        # Override: Hooks in SEND_FILE_MAX_AGE_DEFAULT config.
+        options = super(Flask, self).get_send_file_options(filename)
+        options['cache_timeout'] = self.config['SEND_FILE_MAX_AGE_DEFAULT']
+        return options
+
     @setupmethod
     def template_filter(self, name=None):
         """A decorator that is used to register custom template filter.

flask/helpers.py

@@ -319,6 +319,10 @@ def send_file(filename_or_fp, mimetype=None, as_attachment=False,
     guessing requires a `filename` or an `attachment_filename` to be
     provided.
 
+    Note `get_send_file_options` in :class:`flask.Flask` hooks the
+    ``SEND_FILE_MAX_AGE_DEFAULT`` configuration variable to set the default
+    cache_timeout.
+
     Please never pass filenames to this function from user sources without
     checking them first.  Something like this is usually sufficient to
     avoid security problems::
@@ -652,7 +656,7 @@ class _PackageBoundObject(object):
             return FileSystemLoader(os.path.join(self.root_path,
                                                  self.template_folder))
 
-    def get_static_file_options(self, filename):
+    def get_send_file_options(self, filename):
         """Provides keyword arguments to send to :func:`send_from_directory`.
 
         This allows subclasses to change the behavior when sending files based
@@ -660,14 +664,14 @@ class _PackageBoundObject(object):
         to 60 seconds (note the options are keywords for :func:`send_file`)::
 
             class MyFlask(flask.Flask):
-                def get_static_file_options(self, filename):
-                    options = super(MyFlask, self).get_static_file_options(filename)
+                def get_send_file_options(self, filename):
+                    options = super(MyFlask, self).get_send_file_options(filename)
                     if filename.lower().endswith('.js'):
                         options['cache_timeout'] = 60
                         options['conditional'] = True
                     return options
 
-        .. versionaded:: 0.9
+        .. versionadded:: 0.9
         """
         return {}
 
@@ -680,7 +684,7 @@ class _PackageBoundObject(object):
         if not self.has_static_folder:
             raise RuntimeError('No static folder for this object')
         return send_from_directory(self.static_folder, filename,
-                **self.get_static_file_options(filename))
+                **self.get_send_file_options(filename))
 
     def open_resource(self, resource, mode='rb'):
         """Opens a resource from the application's resource folder.  To see

flask/testsuite/blueprints.py

@@ -16,6 +16,7 @@ import unittest
 import warnings
 from flask.testsuite import FlaskTestCase, emits_module_deprecation_warning
 from werkzeug.exceptions import NotFound
+from werkzeug.http import parse_cache_control_header
 from jinja2 import TemplateNotFound
 
 
@@ -357,6 +358,19 @@ class BlueprintTestCase(FlaskTestCase):
         rv = c.get('/admin/static/css/test.css')
         self.assert_equal(rv.data.strip(), '/* nested file */')
 
+        # try/finally, in case other tests use this app for Blueprint tests.
+        max_age_default = app.config['SEND_FILE_MAX_AGE_DEFAULT']
+        try:
+            expected_max_age = 3600
+            if app.config['SEND_FILE_MAX_AGE_DEFAULT'] == expected_max_age:
+                expected_max_age = 7200
+            app.config['SEND_FILE_MAX_AGE_DEFAULT'] = expected_max_age
+            rv = c.get('/admin/static/css/test.css')
+            cc = parse_cache_control_header(rv.headers['Cache-Control'])
+            self.assert_equal(cc.max_age, expected_max_age)
+        finally:
+            app.config['SEND_FILE_MAX_AGE_DEFAULT'] = max_age_default
+
         with app.test_request_context():
             self.assert_equal(flask.url_for('admin.static', filename='test.txt'),
                               '/admin/static/test.txt')

flask/testsuite/helpers.py

@@ -206,15 +206,20 @@ class SendfileTestCase(FlaskTestCase):
 
     def test_static_file(self):
         app = flask.Flask(__name__)
-        # default cache timeout is 12 hours (hard-coded)
+        # default cache timeout is 12 hours
         with app.test_request_context():
             rv = app.send_static_file('index.html')
             cc = parse_cache_control_header(rv.headers['Cache-Control'])
             self.assert_equal(cc.max_age, 12 * 60 * 60)
-        # override get_static_file_options with some new values and check them
+        app.config['SEND_FILE_MAX_AGE_DEFAULT'] = 3600
+        with app.test_request_context():
+            rv = app.send_static_file('index.html')
+            cc = parse_cache_control_header(rv.headers['Cache-Control'])
+            self.assert_equal(cc.max_age, 3600)
+        # override get_send_file_options with some new values and check them
         class StaticFileApp(flask.Flask):
-            def get_static_file_options(self, filename):
-                opts = super(StaticFileApp, self).get_static_file_options(filename)
+            def get_send_file_options(self, filename):
+                opts = super(StaticFileApp, self).get_send_file_options(filename)
                 opts['cache_timeout'] = 10
                 # this test catches explicit inclusion of the conditional
                 # keyword arg in the guts