[common][utils] Add ensure_string

If the input is of binary type, returns the decoded version.

beat/web/common/utils.py

@@ -28,9 +28,9 @@
 """
 Reusable help functions
 """
-
 from django.core.exceptions import ValidationError
 from django.utils.encoding import force_text
+from django.utils import six
 
 from ..ui.templatetags.markup import restructuredtext
 
@@ -117,3 +117,14 @@ def ensure_html(text):
         return '<pre>{}</pre>'.format(text)
     else:
         return restructuredtext(text)
+
+def ensure_string(data):
+    """
+    Ensure that we have a str object from data which can be either a str in
+    python 2 or a bytes in python 3
+    """
+    if data is not None:
+        if isinstance(data, six.binary_type):
+            return data.decode('utf-8')
+        return data
+    return ''
\ No newline at end of file