Allow user to explicitly set the attribute "Conventions"

lib/iris/fileformats/netcdf.py

@@ -2251,6 +2251,10 @@ def is_valid_packspec(p):
         else:
             conventions = CF_CONVENTIONS_VERSION
 
+        # Prioritise cube attributes conventions over the default.
+        if 'Conventions' in cube.attributes:
+            conventions = cube.attributes['Conventions']
+
         # Perform a CF patch of the conventions attribute.
         cf_profile_available = (iris.site_configuration.get('cf_profile') not
                                 in [None, False])

lib/iris/tests/integration/test_netcdf.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2016, Met Office
+# (C) British Crown Copyright 2014 - 2017, Met Office
 #
 # This file is part of Iris.
 #
@@ -179,22 +179,38 @@ def update(config):
 
 
 class TestConventionsAttributes(tests.IrisTest):
-    def test_patching_conventions_attribute(self):
-        # Ensure that user defined conventions are wiped and those which are
+    def test_patching_conventions_attribute_user_existing(self):
+        # Ensure that user defined conventions pass-thru and those which are
         # saved patched through site_config can be loaded without an exception
         # being raised.
+        conventions = 'some user defined conventions'
         cube = Cube([1.0], standard_name='air_temperature', units='K',
-                    attributes={'Conventions':
-                                'some user defined conventions'})
+                    attributes=dict(Conventions=conventions))
 
         # Patch the site configuration dictionary.
         with _patch_site_configuration(), self.temp_filename('.nc') as nc_path:
             iris.save(cube, nc_path)
             res = iris.load_cube(nc_path)
 
-        self.assertEqual(res.attributes['Conventions'],
-                         '{}, {}, {}'.format(CF_CONVENTIONS_VERSION,
-                                             'convention1', 'convention2'))
+        expected = '{}, {}, {}'.format(conventions,
+                                       'convention1',
+                                       'convention2')
+        self.assertEqual(res.attributes['Conventions'], expected)
+
+    def test_patching_conventions_attribute_user_missing(self):
+        # Ensure that conventions which are saved patched through site_config
+        # can be loaded without an exception being raised.
+        cube = Cube([1.0], standard_name='air_temperature', units='K')
+
+        # Patch the site configuration dictionary.
+        with _patch_site_configuration(), self.temp_filename('.nc') as nc_path:
+            iris.save(cube, nc_path)
+            res = iris.load_cube(nc_path)
+
+        expected = '{}, {}, {}'.format(CF_CONVENTIONS_VERSION,
+                                       'convention1',
+                                       'convention2')
+        self.assertEqual(res.attributes['Conventions'], expected)
 
 
 class TestLazySave(tests.IrisTest):

lib/iris/tests/results/netcdf/netcdf_save_load_ndim_auxiliary.cml

@@ -2,7 +2,7 @@
 <cubes xmlns="urn:x-iris:cubeml-0.2">
   <cube long_name="Precipitation" standard_name="precipitation_flux" units="kg m-2 s-1" var_name="pr">
     <attributes>
-      <attribute name="Conventions" value="CF-1.5"/>
+      <attribute name="Conventions" value="CF-1.0"/>
       <attribute name="NCO" value="4.1.0"/>
       <attribute name="experiment" value="ER3"/>
       <attribute name="history" value="Thu Nov 29 10:45:50 2012: /project/ukmo/rhel6/nco/bin/ncks -d time,0,3 new_rotPole_precipitation.nc small_rotPole_precipitation.nc"/>

lib/iris/tests/results/netcdf/netcdf_save_ndim_auxiliary.cdl

@@ -50,5 +50,5 @@ variables:
 		:history = "Thu Nov 29 10:45:50 2012: /project/ukmo/rhel6/nco/bin/ncks -d time,0,3 new_rotPole_precipitation.nc small_rotPole_precipitation.nc" ;
 		:institution = "DMI" ;
 		:source = "HIRHAM" ;
-		:Conventions = "CF-1.5" ;
+		:Conventions = "CF-1.0" ;
 }

lib/iris/tests/test_netcdf.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2010 - 2016, Met Office
+# (C) British Crown Copyright 2010 - 2017, Met Office
 #
 # This file is part of Iris.
 #
@@ -699,13 +699,10 @@ def test_attributes(self):
         # Should be global attributes.
         aglobals = {'history': 'A long time ago...',
                     'title': 'Attribute test',
-                    'foo': 'bar'}
+                    'foo': 'bar',
+                    'Conventions': 'TEST'}
         for k, v in six.iteritems(aglobals):
             self.cube.attributes[k] = v
-        # Should be overriden.
-        aover = {'Conventions': 'TEST'}
-        for k, v in six.iteritems(aover):
-            self.cube.attributes[k] = v
         # Should be data varible attributes.
         avars = {'standard_error_multiplier': 23,
                  'flag_masks': 'a',
@@ -724,11 +721,7 @@ def test_attributes(self):
                 if getattr(ds, gkey) != aglobals.get(gkey):
                     exceptions.append('{} != {}'.format(getattr(ds, gkey),
                                                         aglobals.get(gkey)))
-            # Should be overriden.
-            for okey in aover:
-                if getattr(ds, okey) == aover.get(okey):
-                    exceptions.append('{} != {}'.format(getattr(ds, okey),
-                                                        avars.get(okey)))
+
             dv = ds['temp']
             # Should be data varible attributes;
             # except STASH -> um_stash_source.

lib/iris/tests/unit/fileformats/netcdf/test_save.py

@@ -48,6 +48,9 @@ def test_custom_conventions__ignored(self):
             ds = nc.Dataset(nc_path)
             res = ds.getncattr('Conventions')
             ds.close()
+        print('testing here')
+        print('res ' + res)
+        print('CF_CONVENTIONS_VERSION ' + CF_CONVENTIONS_VERSION)
         self.assertEqual(res, CF_CONVENTIONS_VERSION)
 
     def test_custom_conventions__allowed(self):