Unhandled GraphQL subscription error Error: GraphQL error: Cannot return null for non-nullable field Subscription.teamCreated

I’m pulling my hair out with this issue…

I’m using this component:

<ListAllTeamsData
    data={data}
    subscribeToMoreTeams={() => {
        subscribeToMore({
            document: LIST_ALL_TEAMS_SUBSCRIPTION,
            updateQuery: (previousResult, { subscriptionData }) => {
                console.log(previousResult, subscriptionData)
                if (!subscriptionData.data) {
                    return previousResult
                }

                const { teamCreated } = subscriptionData.data

                return {
                    ...previousResult,
                    teams: [
                        ...previousResult.teams,
                        teamCreated.team
                    ],
                }
            },
        })
    }}
/>

And the scema:

export const LIST_ALL_TEAMS_SUBSCRIPTION = gql`
    subscription {
        teamCreated {
            team {
                name
                id
                status
                mobile
            }
        }
    }
`

It works fine when I run the subscription in the GraphQL playground, but I get the error in the app. I have no idea why. Any help? It won’t even hit the console.log so there seems to be something wrong with ‘document: LIST_ALL_TEAMS_SUBSCRIPTION’, but from what I can tell it’s all fine.

[jakec-dev]

So the solution was simple. I just changed the server schema so that the return value from the subscription isn’t required.

E.g. from https://github.com/the-road-to-graphql/fullstack-apollo-express-postgresql-boilerplate/blob/master/src/schema/message.js

- line 32: messageCreated: MessageCreated!
+ line 32: messageCreated: MessageCreated

OK to close. Thanks.

[rwieruch]

Anyone who runs into this issue, please leave a comment. Otherwise I will close it the next time I come around here 😃