We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Change is-ticketing-enabled field of Event to dump_only
**I'm submitting a ...**  (check one with "x")
- [ ] bug report
- [x] feature request
- [ ] support request => Please do not submit support requests here, instead ask your query in out Gitter channel at https://gitter.im/fossasia/open-event-server

**Current behavior:**
It is possible to create tickets for an event in which is-ticketing-enabled field is set to false.

**Expected behavior:**
Either the field should be made dump_only or appropiate constraints must be imposed to ckeck this behaviour.

**Steps to reproduce:**
1. Create an event with is-ticketing-enabled attribute to false.
2. Create Ticket for that Event.


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `app/api/tickets.py`
Content:
```
1 from flask_rest_jsonapi import ResourceDetail, ResourceList, ResourceRelationship
2 from flask_rest_jsonapi.exceptions import ObjectNotFound
3 
4 from app.api.bootstrap import api
5 from app.api.helpers.db import safe_query
6 from app.api.helpers.permission_manager import has_access
7 from app.api.helpers.query import event_query
8 from app.api.helpers.utilities import require_relationship
9 from app.api.schema.tickets import TicketSchema, TicketSchemaPublic
10 from app.models import db
11 from app.models.access_code import AccessCode
12 from app.models.order import Order
13 from app.models.ticket import Ticket, TicketTag, ticket_tags_table
14 from app.models.ticket_holder import TicketHolder
15 from app.api.helpers.exceptions import ConflictException
16 from app.api.helpers.db import get_count
17 
18 
19 class TicketListPost(ResourceList):
20     """
21     Create and List Tickets
22     """
23     def before_post(self, args, kwargs, data):
24         """
25         before post method to check for required relationship and proper permission
26         :param args:
27         :param kwargs:
28         :param data:
29         :return:
30         """
31         require_relationship(['event'], data)
32         if not has_access('is_coorganizer', event_id=data['event']):
33             raise ObjectNotFound({'parameter': 'event_id'},
34                                  "Event: {} not found".format(data['event_id']))
35 
36         if get_count(db.session.query(Ticket.id).filter_by(name=data['name'], event_id=int(data['event']))) > 0:
37             raise ConflictException({'pointer': '/data/attributes/name'}, "Ticket already exists")
38 
39     schema = TicketSchema
40     methods = ['POST', ]
41     data_layer = {'session': db.session,
42                   'model': Ticket}
43 
44 
45 class TicketList(ResourceList):
46     """
47     List Tickets based on different params
48     """
49     def before_get(self, args, view_kwargs):
50         """
51         before get method to get the resource id for assigning schema
52         :param args:
53         :param view_kwargs:
54         :return:
55         """
56         if view_kwargs.get('ticket_tag_id') or view_kwargs.get('access_code_id') or view_kwargs.get('order_identifier'):
57             self.schema = TicketSchemaPublic
58 
59     def query(self, view_kwargs):
60         """
61         query method for resource list
62         :param view_kwargs:
63         :return:
64         """
65         query_ = self.session.query(Ticket).filter_by(is_hidden=False)
66         if view_kwargs.get('ticket_tag_id'):
67             ticket_tag = safe_query(self, TicketTag, 'id', view_kwargs['ticket_tag_id'], 'ticket_tag_id')
68             query_ = query_.join(ticket_tags_table).filter_by(ticket_tag_id=ticket_tag.id)
69         query_ = event_query(self, query_, view_kwargs)
70         if view_kwargs.get('access_code_id'):
71             access_code = safe_query(self, AccessCode, 'id', view_kwargs['access_code_id'], 'access_code_id')
72             # access_code - ticket :: many-to-many relationship
73             query_ = Ticket.query.filter(Ticket.access_codes.any(id=access_code.id))
74 
75         if view_kwargs.get('order_identifier'):
76             order = safe_query(self, Order, 'identifier', view_kwargs['order_identifier'], 'order_identifier')
77             ticket_ids = []
78             for ticket in order.tickets:
79                 ticket_ids.append(ticket.id)
80             query_ = query_.filter(Ticket.id.in_(tuple(ticket_ids)))
81 
82         return query_
83 
84     view_kwargs = True
85     methods = ['GET', ]
86     decorators = (api.has_permission('is_coorganizer', fetch='event_id',
87                   fetch_as="event_id", model=Ticket, methods="POST",
88                   check=lambda a: a.get('event_id') or a.get('event_identifier')),)
89     schema = TicketSchema
90     data_layer = {'session': db.session,
91                   'model': Ticket,
92                   'methods': {
93                       'query': query,
94                   }}
95 
96 
97 class TicketDetail(ResourceDetail):
98     """
99     Ticket Resource
100     """
101     def before_get(self, args, view_kwargs):
102         """
103         before get method to get the resource id for assigning schema
104         :param args:
105         :param view_kwargs:
106         :return:
107         """
108         if view_kwargs.get('attendee_id'):
109             self.schema = TicketSchemaPublic
110 
111     def before_get_object(self, view_kwargs):
112         """
113         before get object method to get the resource id for fetching details
114         :param view_kwargs:
115         :return:
116         """
117         if view_kwargs.get('attendee_id') is not None:
118             attendee = safe_query(self, TicketHolder, 'id', view_kwargs['attendee_id'], 'attendee_id')
119             if attendee.ticket_id is not None:
120                 view_kwargs['id'] = attendee.ticket_id
121             else:
122                 view_kwargs['id'] = None
123 
124     decorators = (api.has_permission('is_coorganizer', fetch='event_id',
125                   fetch_as="event_id", model=Ticket, methods="PATCH,DELETE"),)
126     schema = TicketSchema
127     data_layer = {'session': db.session,
128                   'model': Ticket,
129                   'methods': {
130                       'before_get_object': before_get_object
131                   }}
132 
133 
134 class TicketRelationshipRequired(ResourceRelationship):
135     """
136     Tickets Relationship (Required)
137     """
138     decorators = (api.has_permission('is_coorganizer', fetch='event_id',
139                                      fetch_as="event_id", model=Ticket, methods="PATCH"),)
140     methods = ['GET', 'PATCH']
141     schema = TicketSchema
142     data_layer = {'session': db.session,
143                   'model': Ticket}
144 
145 
146 class TicketRelationshipOptional(ResourceRelationship):
147     """
148     Tickets Relationship (Optional)
149     """
150     decorators = (api.has_permission('is_coorganizer', fetch='event_id',
151                                      fetch_as="event_id", model=Ticket, methods="PATCH,DELETE"),)
152     schema = TicketSchema
153     data_layer = {'session': db.session,
154                   'model': Ticket}
155
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/app/api/tickets.py b/app/api/tickets.py
--- a/app/api/tickets.py
+++ b/app/api/tickets.py
@@ -11,8 +11,9 @@
 from app.models.access_code import AccessCode
 from app.models.order import Order
 from app.models.ticket import Ticket, TicketTag, ticket_tags_table
+from app.models.event import Event
 from app.models.ticket_holder import TicketHolder
-from app.api.helpers.exceptions import ConflictException
+from app.api.helpers.exceptions import ConflictException, MethodNotAllowed
 from app.api.helpers.db import get_count
 
 
@@ -36,6 +37,9 @@
         if get_count(db.session.query(Ticket.id).filter_by(name=data['name'], event_id=int(data['event']))) > 0:
             raise ConflictException({'pointer': '/data/attributes/name'}, "Ticket already exists")
 
+        if get_count(db.session.query(Event).filter_by(id=int(data['event']), is_ticketing_enabled=False)) > 0:
+            raise MethodNotAllowed({'parameter': 'event_id'}, "Ticketing is disabled for this Event")
+
     schema = TicketSchema
     methods = ['POST', ]
     data_layer = {'session': db.session,

{"golden_diff": "diff --git a/app/api/tickets.py b/app/api/tickets.py\n--- a/app/api/tickets.py\n+++ b/app/api/tickets.py\n@@ -11,8 +11,9 @@\n from app.models.access_code import AccessCode\n from app.models.order import Order\n from app.models.ticket import Ticket, TicketTag, ticket_tags_table\n+from app.models.event import Event\n from app.models.ticket_holder import TicketHolder\n-from app.api.helpers.exceptions import ConflictException\n+from app.api.helpers.exceptions import ConflictException, MethodNotAllowed\n from app.api.helpers.db import get_count\n \n \n@@ -36,6 +37,9 @@\n         if get_count(db.session.query(Ticket.id).filter_by(name=data['name'], event_id=int(data['event']))) > 0:\n             raise ConflictException({'pointer': '/data/attributes/name'}, \"Ticket already exists\")\n \n+        if get_count(db.session.query(Event).filter_by(id=int(data['event']), is_ticketing_enabled=False)) > 0:\n+            raise MethodNotAllowed({'parameter': 'event_id'}, \"Ticketing is disabled for this Event\")\n+\n     schema = TicketSchema\n     methods = ['POST', ]\n     data_layer = {'session': db.session,\n", "issue": "Change is-ticketing-enabled field of Event to dump_only\n**I'm submitting a ...**  (check one with \"x\")\r\n- [ ] bug report\r\n- [x] feature request\r\n- [ ] support request => Please do not submit support requests here, instead ask your query in out Gitter channel at https://gitter.im/fossasia/open-event-server\r\n\r\n**Current behavior:**\r\nIt is possible to create tickets for an event in which is-ticketing-enabled field is set to false.\r\n\r\n**Expected behavior:**\r\nEither the field should be made dump_only or appropiate constraints must be imposed to ckeck this behaviour.\r\n\r\n**Steps to reproduce:**\r\n1. Create an event with is-ticketing-enabled attribute to false.\r\n2. Create Ticket for that Event.\r\n\n", "before_files": [{"content": "from flask_rest_jsonapi import ResourceDetail, ResourceList, ResourceRelationship\nfrom flask_rest_jsonapi.exceptions import ObjectNotFound\n\nfrom app.api.bootstrap import api\nfrom app.api.helpers.db import safe_query\nfrom app.api.helpers.permission_manager import has_access\nfrom app.api.helpers.query import event_query\nfrom app.api.helpers.utilities import require_relationship\nfrom app.api.schema.tickets import TicketSchema, TicketSchemaPublic\nfrom app.models import db\nfrom app.models.access_code import AccessCode\nfrom app.models.order import Order\nfrom app.models.ticket import Ticket, TicketTag, ticket_tags_table\nfrom app.models.ticket_holder import TicketHolder\nfrom app.api.helpers.exceptions import ConflictException\nfrom app.api.helpers.db import get_count\n\n\nclass TicketListPost(ResourceList):\n    \"\"\"\n    Create and List Tickets\n    \"\"\"\n    def before_post(self, args, kwargs, data):\n        \"\"\"\n        before post method to check for required relationship and proper permission\n        :param args:\n        :param kwargs:\n        :param data:\n        :return:\n        \"\"\"\n        require_relationship(['event'], data)\n        if not has_access('is_coorganizer', event_id=data['event']):\n            raise ObjectNotFound({'parameter': 'event_id'},\n                                 \"Event: {} not found\".format(data['event_id']))\n\n        if get_count(db.session.query(Ticket.id).filter_by(name=data['name'], event_id=int(data['event']))) > 0:\n            raise ConflictException({'pointer': '/data/attributes/name'}, \"Ticket already exists\")\n\n    schema = TicketSchema\n    methods = ['POST', ]\n    data_layer = {'session': db.session,\n                  'model': Ticket}\n\n\nclass TicketList(ResourceList):\n    \"\"\"\n    List Tickets based on different params\n    \"\"\"\n    def before_get(self, args, view_kwargs):\n        \"\"\"\n        before get method to get the resource id for assigning schema\n        :param args:\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        if view_kwargs.get('ticket_tag_id') or view_kwargs.get('access_code_id') or view_kwargs.get('order_identifier'):\n            self.schema = TicketSchemaPublic\n\n    def query(self, view_kwargs):\n        \"\"\"\n        query method for resource list\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        query_ = self.session.query(Ticket).filter_by(is_hidden=False)\n        if view_kwargs.get('ticket_tag_id'):\n            ticket_tag = safe_query(self, TicketTag, 'id', view_kwargs['ticket_tag_id'], 'ticket_tag_id')\n            query_ = query_.join(ticket_tags_table).filter_by(ticket_tag_id=ticket_tag.id)\n        query_ = event_query(self, query_, view_kwargs)\n        if view_kwargs.get('access_code_id'):\n            access_code = safe_query(self, AccessCode, 'id', view_kwargs['access_code_id'], 'access_code_id')\n            # access_code - ticket :: many-to-many relationship\n            query_ = Ticket.query.filter(Ticket.access_codes.any(id=access_code.id))\n\n        if view_kwargs.get('order_identifier'):\n            order = safe_query(self, Order, 'identifier', view_kwargs['order_identifier'], 'order_identifier')\n            ticket_ids = []\n            for ticket in order.tickets:\n                ticket_ids.append(ticket.id)\n            query_ = query_.filter(Ticket.id.in_(tuple(ticket_ids)))\n\n        return query_\n\n    view_kwargs = True\n    methods = ['GET', ]\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                  fetch_as=\"event_id\", model=Ticket, methods=\"POST\",\n                  check=lambda a: a.get('event_id') or a.get('event_identifier')),)\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket,\n                  'methods': {\n                      'query': query,\n                  }}\n\n\nclass TicketDetail(ResourceDetail):\n    \"\"\"\n    Ticket Resource\n    \"\"\"\n    def before_get(self, args, view_kwargs):\n        \"\"\"\n        before get method to get the resource id for assigning schema\n        :param args:\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        if view_kwargs.get('attendee_id'):\n            self.schema = TicketSchemaPublic\n\n    def before_get_object(self, view_kwargs):\n        \"\"\"\n        before get object method to get the resource id for fetching details\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        if view_kwargs.get('attendee_id') is not None:\n            attendee = safe_query(self, TicketHolder, 'id', view_kwargs['attendee_id'], 'attendee_id')\n            if attendee.ticket_id is not None:\n                view_kwargs['id'] = attendee.ticket_id\n            else:\n                view_kwargs['id'] = None\n\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                  fetch_as=\"event_id\", model=Ticket, methods=\"PATCH,DELETE\"),)\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket,\n                  'methods': {\n                      'before_get_object': before_get_object\n                  }}\n\n\nclass TicketRelationshipRequired(ResourceRelationship):\n    \"\"\"\n    Tickets Relationship (Required)\n    \"\"\"\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                                     fetch_as=\"event_id\", model=Ticket, methods=\"PATCH\"),)\n    methods = ['GET', 'PATCH']\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket}\n\n\nclass TicketRelationshipOptional(ResourceRelationship):\n    \"\"\"\n    Tickets Relationship (Optional)\n    \"\"\"\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                                     fetch_as=\"event_id\", model=Ticket, methods=\"PATCH,DELETE\"),)\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket}\n", "path": "app/api/tickets.py"}], "after_files": [{"content": "from flask_rest_jsonapi import ResourceDetail, ResourceList, ResourceRelationship\nfrom flask_rest_jsonapi.exceptions import ObjectNotFound\n\nfrom app.api.bootstrap import api\nfrom app.api.helpers.db import safe_query\nfrom app.api.helpers.permission_manager import has_access\nfrom app.api.helpers.query import event_query\nfrom app.api.helpers.utilities import require_relationship\nfrom app.api.schema.tickets import TicketSchema, TicketSchemaPublic\nfrom app.models import db\nfrom app.models.access_code import AccessCode\nfrom app.models.order import Order\nfrom app.models.ticket import Ticket, TicketTag, ticket_tags_table\nfrom app.models.event import Event\nfrom app.models.ticket_holder import TicketHolder\nfrom app.api.helpers.exceptions import ConflictException, MethodNotAllowed\nfrom app.api.helpers.db import get_count\n\n\nclass TicketListPost(ResourceList):\n    \"\"\"\n    Create and List Tickets\n    \"\"\"\n    def before_post(self, args, kwargs, data):\n        \"\"\"\n        before post method to check for required relationship and proper permission\n        :param args:\n        :param kwargs:\n        :param data:\n        :return:\n        \"\"\"\n        require_relationship(['event'], data)\n        if not has_access('is_coorganizer', event_id=data['event']):\n            raise ObjectNotFound({'parameter': 'event_id'},\n                                 \"Event: {} not found\".format(data['event_id']))\n\n        if get_count(db.session.query(Ticket.id).filter_by(name=data['name'], event_id=int(data['event']))) > 0:\n            raise ConflictException({'pointer': '/data/attributes/name'}, \"Ticket already exists\")\n\n        if get_count(db.session.query(Event).filter_by(id=int(data['event']), is_ticketing_enabled=False)) > 0:\n            raise MethodNotAllowed({'parameter': 'event_id'}, \"Ticketing is disabled for this Event\")\n\n    schema = TicketSchema\n    methods = ['POST', ]\n    data_layer = {'session': db.session,\n                  'model': Ticket}\n\n\nclass TicketList(ResourceList):\n    \"\"\"\n    List Tickets based on different params\n    \"\"\"\n    def before_get(self, args, view_kwargs):\n        \"\"\"\n        before get method to get the resource id for assigning schema\n        :param args:\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        if view_kwargs.get('ticket_tag_id') or view_kwargs.get('access_code_id') or view_kwargs.get('order_identifier'):\n            self.schema = TicketSchemaPublic\n\n    def query(self, view_kwargs):\n        \"\"\"\n        query method for resource list\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        query_ = self.session.query(Ticket).filter_by(is_hidden=False)\n        if view_kwargs.get('ticket_tag_id'):\n            ticket_tag = safe_query(self, TicketTag, 'id', view_kwargs['ticket_tag_id'], 'ticket_tag_id')\n            query_ = query_.join(ticket_tags_table).filter_by(ticket_tag_id=ticket_tag.id)\n        query_ = event_query(self, query_, view_kwargs)\n        if view_kwargs.get('access_code_id'):\n            access_code = safe_query(self, AccessCode, 'id', view_kwargs['access_code_id'], 'access_code_id')\n            # access_code - ticket :: many-to-many relationship\n            query_ = Ticket.query.filter(Ticket.access_codes.any(id=access_code.id))\n\n        if view_kwargs.get('order_identifier'):\n            order = safe_query(self, Order, 'identifier', view_kwargs['order_identifier'], 'order_identifier')\n            ticket_ids = []\n            for ticket in order.tickets:\n                ticket_ids.append(ticket.id)\n            query_ = query_.filter(Ticket.id.in_(tuple(ticket_ids)))\n\n        return query_\n\n    view_kwargs = True\n    methods = ['GET', ]\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                  fetch_as=\"event_id\", model=Ticket, methods=\"POST\",\n                  check=lambda a: a.get('event_id') or a.get('event_identifier')),)\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket,\n                  'methods': {\n                      'query': query,\n                  }}\n\n\nclass TicketDetail(ResourceDetail):\n    \"\"\"\n    Ticket Resource\n    \"\"\"\n    def before_get(self, args, view_kwargs):\n        \"\"\"\n        before get method to get the resource id for assigning schema\n        :param args:\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        if view_kwargs.get('attendee_id'):\n            self.schema = TicketSchemaPublic\n\n    def before_get_object(self, view_kwargs):\n        \"\"\"\n        before get object method to get the resource id for fetching details\n        :param view_kwargs:\n        :return:\n        \"\"\"\n        if view_kwargs.get('attendee_id') is not None:\n            attendee = safe_query(self, TicketHolder, 'id', view_kwargs['attendee_id'], 'attendee_id')\n            if attendee.ticket_id is not None:\n                view_kwargs['id'] = attendee.ticket_id\n            else:\n                view_kwargs['id'] = None\n\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                  fetch_as=\"event_id\", model=Ticket, methods=\"PATCH,DELETE\"),)\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket,\n                  'methods': {\n                      'before_get_object': before_get_object\n                  }}\n\n\nclass TicketRelationshipRequired(ResourceRelationship):\n    \"\"\"\n    Tickets Relationship (Required)\n    \"\"\"\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                                     fetch_as=\"event_id\", model=Ticket, methods=\"PATCH\"),)\n    methods = ['GET', 'PATCH']\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket}\n\n\nclass TicketRelationshipOptional(ResourceRelationship):\n    \"\"\"\n    Tickets Relationship (Optional)\n    \"\"\"\n    decorators = (api.has_permission('is_coorganizer', fetch='event_id',\n                                     fetch_as=\"event_id\", model=Ticket, methods=\"PATCH,DELETE\"),)\n    schema = TicketSchema\n    data_layer = {'session': db.session,\n                  'model': Ticket}\n", "path": "app/api/tickets.py"}]}