[#1894] Fix convert_to_extras to allow use with normal extras

`convert_to_extras` was adding the custom fields in an unflattened way
during validation to the object that would be later unflattened. This
worked fine if there were only `convert_to_extras` fields, but not if
you were also providing actual extras, eg

    data_dict = {
        'name': 'test-dataset',
        'custom_text': 'Hi',
        'custom_text2': 'Hi2',
        'extras': [
            {'key': 'proper_extra', 'value': 'Bye'},
        ]

    }

This fixes the `convert_to_extras` output and adds new converters test for it.

ckan/logic/converters.py

@@ -7,11 +7,18 @@
 
 from ckan.common import _
 
+
 def convert_to_extras(key, data, errors, context):
-    extras = data.get(('extras',), [])
-    if not extras:
-        data[('extras',)] = extras
-    extras.append({'key': key[-1], 'value': data[key]})
+
+    # Get the current extras index
+    current_indexes = [k[1] for k in data.keys()
+                       if len(k) > 1 and k[0] == 'extras']
+
+    new_index = max(current_indexes) + 1 if current_indexes else 0
+
+    data[('extras', new_index, 'key')] = key[-1]
+    data[('extras', new_index, 'value')] = data[key]
+
 
 def convert_from_extras(key, data, errors, context):
 

ckan/new_tests/lib/navl/test_converters.py

@@ -0,0 +1,98 @@
+import nose
+
+from ckan import model
+import ckan.plugins as p
+import ckan.lib.plugins as lib_plugins
+from ckan.lib.navl.dictization_functions import validate
+
+
+eq_ = nose.tools.eq_
+
+
+class TestConvertToExtras(object):
+
+    @classmethod
+    def setup_class(cls):
+        p.load('example_idatasetform')
+
+    @classmethod
+    def teardown_class(cls):
+        p.unload('example_idatasetform')
+
+    def test_convert_to_extras_field_gets_stored_as_extra(self):
+
+        data_dict = {
+            'name': 'test-dataset',
+            'custom_text': 'Hi',
+        }
+
+        context = {
+            'model': model,
+            'session': model.Session,
+        }
+
+        package_plugin = lib_plugins.lookup_package_plugin('dataset')
+        schema = package_plugin.create_package_schema()
+
+        data, errors = validate(data_dict, schema, context)
+
+        assert 'extras' in data
+        eq_(len(data['extras']), 1)
+        eq_(data['extras'][0]['key'], 'custom_text')
+        eq_(data['extras'][0]['value'], 'Hi')
+
+    def test_convert_to_extras_field_can_be_combined_with_a_proper_extra(self):
+
+        data_dict = {
+            'name': 'test-dataset',
+            'custom_text': 'Hi',
+            'extras': [
+                {'key': 'proper_extra', 'value': 'Bye'},
+
+            ]
+        }
+
+        context = {
+            'model': model,
+            'session': model.Session,
+        }
+
+        package_plugin = lib_plugins.lookup_package_plugin('dataset')
+        schema = package_plugin.create_package_schema()
+
+        data, errors = validate(data_dict, schema, context)
+
+        assert 'extras' in data
+        eq_(len(data['extras']), 2)
+        eq_(sorted([e['key'] for e in data['extras']]),
+            ['custom_text', 'proper_extra'])
+        eq_(sorted([e['value'] for e in data['extras']]),
+            ['Bye', 'Hi'])
+
+    def test_convert_to_extras_field_can_be_combined_with_more_extras(self):
+
+        data_dict = {
+            'name': 'test-dataset',
+            'custom_text': 'Hi',
+            'extras': [
+                {'key': 'proper_extra', 'value': 'Bye'},
+                {'key': 'proper_extra2', 'value': 'Bye2'},
+            ]
+        }
+
+        context = {
+            'model': model,
+            'session': model.Session,
+        }
+
+        package_plugin = lib_plugins.lookup_package_plugin('dataset')
+        schema = package_plugin.create_package_schema()
+
+        data, errors = validate(data_dict, schema, context)
+
+        assert 'extras' in data
+        eq_(len(data['extras']), 3)
+        eq_(sorted([e['key'] for e in data['extras']]),
+            ['custom_text', 'proper_extra', 'proper_extra2'])
+        eq_(sorted([e['value'] for e in data['extras']]),
+            ['Bye', 'Bye2', 'Hi'])