A participant's unique id exceeded 50 chars
unique_id is a String(50) column in the Participant table.

Today this caused an error as a request to create a participant was received with a unique_id of u'A0384[redacted 16 characters]:3YOH7BII097S091VIWGYDU7IGJLVKI'. This is 55 chars long and so it wouldn't fit in the table.

It is trivial to allow longer strings in the table, but do we want to do this? I thought worker/assignment ids were of fixed length, in which case this probably indicates an error somewhere.

What do we think?
diff --git a/dallinger/models.py b/dallinger/models.py
index 81944b8c..d0bb3f27 100644
--- a/dallinger/models.py
+++ b/dallinger/models.py
@@ -86,7 +86,7 @@ class Participant(Base, SharedMixin):
 
     #: A String, a concatenation of :attr:`~dallinger.models.Participant.worker_id`
     #: and :attr:`~dallinger.models.Participant.assignment_id`, used by psiTurk.
-    unique_id = Column(String(50), nullable=False, index=True)
+    unique_id = Column(String(75), nullable=False, index=True)
 
     #: A String, the id of the hit the participant is working on
     hit_id = Column(String(50), nullable=False)
['dallinger/models.py']