Refactor file field checking.

When uploading, the file field needs some checks, it seems.
So refactor them into check_file_field and use around.

mediagoblin/plugins/api/views.py

@@ -18,7 +18,6 @@ import json
 import logging
 
 from os.path import splitext
-from werkzeug.datastructures import FileStorage
 from werkzeug.exceptions import BadRequest, Forbidden
 from werkzeug.wrappers import Response
 
@@ -27,7 +26,8 @@ from mediagoblin.meddleware.csrf import csrf_exempt
 from mediagoblin.media_types import sniff_media
 from mediagoblin.plugins.api.tools import api_auth, get_entry_serializable, \
         json_response
-from mediagoblin.submit.lib import prepare_queue_task, run_process_media
+from mediagoblin.submit.lib import check_file_field, prepare_queue_task, \
+    run_process_media
 
 _log = logging.getLogger(__name__)
 
@@ -45,9 +45,7 @@ def post_entry(request):
         _log.debug('Must POST against post_entry')
         raise BadRequest()
 
-    if not 'file' in request.files \
+    if not check_file_field(request, 'file'):
-            or not isinstance(request.files['file'], FileStorage) \
-            or not request.files['file'].stream:
         _log.debug('File field not found')
         raise BadRequest()
 

mediagoblin/submit/lib.py

@@ -17,6 +17,7 @@
 import logging
 import uuid
 from werkzeug.utils import secure_filename
+from werkzeug.datastructures import FileStorage
 
 from mediagoblin.processing import mark_entry_failed
 from mediagoblin.processing.task import process_media
@@ -25,6 +26,16 @@ from mediagoblin.processing.task import process_media
 _log = logging.getLogger(__name__)
 
 
+def check_file_field(request, field_name):
+    """Check if a file field meets minimal criteria"""
+    retval = (field_name in request.files
+              and isinstance(request.files[field_name], FileStorage)
+              and request.files[field_name].stream)
+    if not retval:
+        _log.debug("Form did not contain proper file field %s", field_name)
+    return retval
+
+
 def prepare_queue_task(app, entry, filename):
     """
     Prepare a MediaEntry for the processing queue and get a queue file

mediagoblin/submit/views.py

@@ -22,7 +22,6 @@ import logging
 
 _log = logging.getLogger(__name__)
 
-from werkzeug.datastructures import FileStorage
 
 from mediagoblin.tools.text import convert_to_tag_list_of_dicts
 from mediagoblin.tools.translate import pass_to_ugettext as _
@@ -32,7 +31,8 @@ from mediagoblin.submit import forms as submit_forms
 from mediagoblin.messages import add_message, SUCCESS
 from mediagoblin.media_types import sniff_media, \
     InvalidFileType, FileTypeNotSupported
-from mediagoblin.submit.lib import run_process_media, prepare_queue_task
+from mediagoblin.submit.lib import check_file_field, prepare_queue_task, \
+    run_process_media
 
 
 @require_active_login
@@ -44,9 +44,7 @@ def submit_start(request):
         license=request.user.license_preference)
 
     if request.method == 'POST' and submit_form.validate():
-        if not ('file' in request.files
+        if not check_file_field(request, 'file'):
-                and isinstance(request.files['file'], FileStorage)
-                and request.files['file'].stream):
             submit_form.file.errors.append(
                 _(u'You must provide a file.'))
         else: