Database errors reporting at REST level

gargantext/backend/__init__.py

 from .celery_app import app as celery_app
+from . import exceptions # Need to import this here to activate error handling

gargantext/backend/exceptions.py

+"""
+This module handles automatic conversion between SQLAlchemy's exceptions and
+Django REST framework's APIException.
+
+It mimics behavior of PostgREST, hereunder is the conversion table between
+PostgreSQL errors and HTTP statuses.
+
+See https://postgrest.com/en/v4.3/api.html#http-status-codes
+
+HTTP 400 → Bad Request
+HTTP 401 → Unauthorized
+HTTP 403 → Forbidden
+HTTP 404 → Not Found
+HTTP 409 → Conflict
+HTTP 413 → Payload Too Large
+HTTP 500 → Server Internal Error
+HTTP 503 → Service Unavailable
+
+Error code(s) | HTTP status                   | Error description
+==============|===============================|================================
+08*           | 503                           | pg connection err
+09*           | 500                           | triggered action exception
+0L*           | 403                           | invalid grantor
+0P*           | 403                           | invalid role specification
+23503         | 409                           | foreign key violation
+23505         | 409                           | uniqueness violation
+25*           | 500                           | invalid transaction state
+28*           | 403                           | invalid auth specification
+2D*           | 500                           | invalid transaction termination
+38*           | 500                           | external routine exception
+39*           | 500                           | external routine invocation
+3B*           | 500                           | savepoint exception
+40*           | 500                           | transaction rollback
+53*           | 503                           | insufficient resources
+54*           | 413                           | too complex
+55*           | 500                           | obj not in prerequisite state
+57*           | 500                           | operator intervention
+58*           | 500                           | system error
+F0*           | 500                           | conf file error
+HV*           | 500                           | foreign data wrapper error
+P0001         | 400                           | default code for “raise”
+P0*           | 500                           | PL/pgSQL error
+XX*           | 500                           | internal error
+42883         | 404                           | undefined function
+42P01         | 404                           | undefined table
+42501         | if authenticated 403 else 401 | insufficient privileges
+other         | 500                           |
+
+"""
+import logging
+
+from sqlalchemy import event
+from rest_framework.exceptions import APIException
+
+from gargantext.core.db import protected_engine
+
+
+logger = logging.getLogger('gargantext.backend')
+
+
+PGERROR_TO_HTTPSTATUS = {
+    '08'   : 503,
+    '09'   : 500,
+    '0L'   : 403,
+    '0P'   : 403,
+    '23503': 409,
+    '23505': 409,
+    '25'   : 500,
+    '28'   : 403,
+    '2D'   : 500,
+    '38'   : 500,
+    '39'   : 500,
+    '3B'   : 500,
+    '40'   : 500,
+    '53'   : 503,
+    '54'   : 413,
+    '55'   : 500,
+    '57'   : 500,
+    '58'   : 500,
+    'F0'   : 500,
+    'HV'   : 500,
+    'P0001': 400,
+    'P0'   : 500,
+    'XX'   : 500,
+    '42883': 404,
+    '42P01': 404,
+    '42501': lambda c: 403 if c.info.get('authenticated') else 401
+}
+
+
+class DatabaseError(APIException):
+    """Represent any gargantext database exception.
+
+    Intended to be used in with SQLAlchemy's `handler_error` signal, to convert
+    any database error to a local one, and ease database error handling.
+
+    Arguments:
+    conn -- SQLAlchemy connection
+    orig_exc -- SQLALchemy original exception
+    """
+    def __init__(self, conn, orig_exc):
+        # Error code
+        code = orig_exc.pgcode or '??'
+
+        # Whole error message
+        error = str(orig_exc.pgerror or \
+            (orig_exc.args and orig_exc.args[0]) or '')
+
+        # XXX PostgREST takes care of each error part (MESSAGE, DETAIL, HINT,
+        #     ERRCODE), we don't replicate this behavior.
+        # See https://www.postgresql.org/docs/9.3/static/plpgsql-errors-and-messages.html
+        first_line = error.split('\n', 2)[0]
+        parts = first_line.split(':', 2)
+
+        # Extract a meaningful message
+        message = parts[1 if len(parts) > 1 else 0].strip()
+
+        # Search error code in PGERROR_TO_HTTPSTATUS:
+        # * Try first with two first chars of the error code
+        # * Then try with the entire code
+        status = PGERROR_TO_HTTPSTATUS.get(
+            code[:1],
+            PGERROR_TO_HTTPSTATUS.get(code, 500))
+
+        if callable(status):
+            status = status(conn)
+
+        self.status_code = status
+
+        super().__init__(code=code, detail=message)
+
+        self.args = (orig_exc,)
+
+
+# See http://docs.sqlalchemy.org/en/latest/core/events.html#sqlalchemy.events.ConnectionEvents.handle_error
+@event.listens_for(protected_engine, 'handle_error', named=True)
+def receive_handle_error(exception_context):
+    exc = DatabaseError(
+        exception_context.connection, exception_context.original_exception)
+
+    logger.exception(exc)
+
+    raise exc
+
+
+def base_exception_handler(exc, context):
+    from rest_framework.views import exception_handler as _exception_handler
+
+    response = _exception_handler(exc, context)
+
+    session = context['request'].db
+    session.rollback()
+
+    return response

gargantext/backend/views.py

+from .exceptions import base_exception_handler
+
+
+def exception_handler(exc, context):
+    response = base_exception_handler(exc, context)
+
+    if response is not None:
+        code = getattr(response.data.get('detail'), 'code', None)
+        if code:
+            response.data['code'] = code
+        response.data['status_code'] = response.status_code
+
+    return response

gargantext/settings.py

@@ -228,6 +228,7 @@ REST_FRAMEWORK = {
         'gargantext.backend.authentication.JWTAuthentication',
         'gargantext.backend.authentication.AnonymousAuthentication',
     ),
+    'EXCEPTION_HANDLER': 'gargantext.backend.views.exception_handler',
 }
 
 # See http://getblimp.github.io/django-rest-framework-jwt/