Error Handing¶
Local errors¶
If gql detects locally that something does not correspond to the GraphQL specification, then gql may raise a GraphQLError from graphql-core.
This may happen for example:
if your query is not valid
if your query does not correspond to your schema
if the result received from the backend does not correspond to the schema if
parse_results
is set to True
Transport errors¶
If an error happens with the transport, then gql may raise a
TransportError
Here are the possible Transport Errors:
TransportProtocolError
: Should never happen if the backend is a correctly configured GraphQL server. It means that the answer received from the server does not correspond to the transport protocol.TransportServerError
: There was an error communicating with the server. If this error is received, then the connection with the server will be closed. This may happen if the server returned a 404 http header for example. The http error code is available in the exceptioncode
attribute.TransportQueryError
: There was a specific error returned from the server for your query. The message you receive in this error has been created by the backend, not gql! In that case, the connection to the server is still available and you are free to try to send other queries using the same connection. The message of the exception contains the first error returned by the backend. All the errors messages are available in the exceptionerrors
attribute.TransportClosed
: This exception is generated when the client is trying to use the transport while the transport was previously closed.TransportAlreadyConnected
: Exception generated when the client is trying to connect to the transport while the transport is already connected.
HTTP¶
For HTTP transports, we should get a json response which contain
data
or errors
fields.
If that is not the case, then the returned error depends whether the http return code
is below 400 or not.
- json response:
- with data or errors keys:
no errors key -> no exception
errors key -> raise TransportQueryError
- no data or errors keys:
http code < 400: raise TransportProtocolError
http code >= 400: raise TransportServerError
- not a json response:
http code < 400: raise TransportProtocolError
http code >= 400: raise TransportServerError