rebaseline_server: allow JSON to control column filtering

gm/rebaseline_server/imagepairset.py

 #!/usr/bin/python
 
 """
 Copyright 2014 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 
 ImagePairSet class; see its docstring below.
 """
 
 # System-level imports
 import posixpath
 
 # Local imports
 import column
 import imagediffdb
 
 # Keys used within dictionary representation of ImagePairSet.
 # NOTE: Keep these in sync with static/constants.js
 KEY__ROOT__EXTRACOLUMNHEADERS = 'extraColumnHeaders'
+KEY__ROOT__EXTRACOLUMNORDER = 'extraColumnOrder'
 KEY__ROOT__HEADER = 'header'
 KEY__ROOT__IMAGEPAIRS = 'imagePairs'
 KEY__ROOT__IMAGESETS = 'imageSets'
 KEY__IMAGESETS__FIELD__BASE_URL = 'baseUrl'
 KEY__IMAGESETS__FIELD__DESCRIPTION = 'description'
 KEY__IMAGESETS__SET__DIFFS = 'diffs'
 KEY__IMAGESETS__SET__IMAGE_A = 'imageA'
 KEY__IMAGESETS__SET__IMAGE_B = 'imageB'
 KEY__IMAGESETS__SET__WHITEDIFFS = 'whiteDiffs'
 
@@ skipping 96 matching lines @@
 
   def _column_headers_as_dict(self):
     """Returns all column headers as a dictionary."""
     asdict = {}
     for column_id, values_for_column in self._extra_column_tallies.iteritems():
       column_header_factory = self.get_column_header_factory(column_id)
       asdict[column_id] = column_header_factory.create_as_dict(
           values_for_column)
     return asdict
 
-  def as_dict(self):
+  def as_dict(self, column_ids_in_order=None):
     """Returns a dictionary describing this package of ImagePairs.
 
     Uses the KEY__* constants as keys.
+
+    Params:
+      column_ids_in_order: A list of all extracolumn IDs in the desired display
+          order.  If unspecified, they will be displayed in alphabetical order.
+          If specified, this list must contain all the extracolumn IDs!
+          (It may contain extra column IDs; they will be ignored.)
     """
+    all_column_ids = set(self._extra_column_tallies.keys())
+    if column_ids_in_order == None:
+      column_ids_in_order = sorted(all_column_ids)
+    else:
+      # Make sure the caller listed all column IDs, and throw away any extras.
+      specified_column_ids = set(column_ids_in_order)
+      forgotten_column_ids = all_column_ids - specified_column_ids
+      assert not forgotten_column_ids, (
+          'column_ids_in_order %s missing these column_ids: %s' % (
+              column_ids_in_order, forgotten_column_ids))
+      column_ids_in_order = [c for c in column_ids_in_order
+                             if c in all_column_ids]
+
     key_description = KEY__IMAGESETS__FIELD__DESCRIPTION
     key_base_url = KEY__IMAGESETS__FIELD__BASE_URL
     return {
         KEY__ROOT__EXTRACOLUMNHEADERS: self._column_headers_as_dict(),
+        KEY__ROOT__EXTRACOLUMNORDER: column_ids_in_order,
         KEY__ROOT__IMAGEPAIRS: self._image_pair_dicts,
         KEY__ROOT__IMAGESETS: {
             KEY__IMAGESETS__SET__IMAGE_A: {
                 key_description: self._descriptions[0],
                 key_base_url: self._image_base_url,
             },
             KEY__IMAGESETS__SET__IMAGE_B: {
                 key_description: self._descriptions[1],
                 key_base_url: self._image_base_url,
             },
             KEY__IMAGESETS__SET__DIFFS: {
                 key_description: 'color difference per channel',
                 key_base_url: posixpath.join(
                     self._diff_base_url, imagediffdb.RGBDIFFS_SUBDIR),
             },
             KEY__IMAGESETS__SET__WHITEDIFFS: {
                 key_description: 'differing pixels in white',
                 key_base_url: posixpath.join(
                     self._diff_base_url, imagediffdb.WHITEDIFFS_SUBDIR),
             },
         },
     }