Add the Response model

This is to store RSVPs.

calsocial/models.py

@@ -74,6 +74,35 @@ NOTIFICATION_ACTION_MESSAGES = {
 }
 
 
+class ResponseType(Enum):
+    """Enumeration of event availabilities
+    """
+
+    #: The user is about to attend the event
+    going = 0
+
+    #: The user will probably attend the event
+    probably_going = 1
+
+    #: The user is interested in the event, but might not go
+    probably_not_going = 2
+
+    #: The user won’t attend the event
+    not_going = 3
+
+    def __hash__(self):
+        return Enum.__hash__(self)
+
+    def __eq__(self, other):
+        if isinstance(other, str):
+            return self.name.lower() == other.lower()  # pylint: disable=no-member
+
+        if isinstance(other, (int, float)):
+            return self.value == other
+
+        return Enum.__eq__(self, other)
+
+
 class SettingsProxy:
     """Proxy object to get settings for a user
     """
@@ -617,3 +646,31 @@ class Invitation(db.Model):  # pylint: disable=too-few-public-methods
 
     #: The timestamp of the invitation
     timestamp = db.Column(db.DateTime(), default=datetime.utcnow)
+
+
+class Response(db.Model):  # pylint: disable=too-few-public-methods
+    """Database model for RSVPs.
+    """
+
+    __tablename__ = 'responses'
+
+    #: The profile that’s sending the RSVP
+    profile_id = db.Column(db.Integer(), db.ForeignKey('profiles.id'), primary_key=True)
+
+    profile = db.relationship('Profile')
+
+    #: The ID of the event
+    event_id = db.Column(db.Integer(), db.ForeignKey('events.id'), primary_key=True)
+
+    event = db.relationship('Event')
+
+    #: The ID of the invitation, if the user is responding to an invitation
+    invitation_id = db.Column(db.Integer(), db.ForeignKey('invitations.id'), nullable=True)
+
+    invitation = db.relationship('Invitation')
+
+    #: The timestamp of the response
+    timestamp = db.Column(db.DateTime(), default=datetime.utcnow)
+
+    #: The response itself
+    response = db.Column(db.Enum(ResponseType), nullable=False)