Error handling

[mununki]

Hi,

In case of having an error of GraphQLError from the gql api, the compiled query code throwing an error such as,

Uncaught TypeError: Cannot read property '__typename' of null
    at parse (Query.bs.js:27)
    at mapU (belt_Option.js:57)
    at Module.map (belt_Option.js:63)
    at Object.fromJs (ApolloClient__React_Types.bs.js:162)
    at eval (ApolloClient__React_Hooks_UseQuery.bs.js:52)
    at Module._1 (curry.js:51)
    at Module.useGuaranteedMemo1 (ApolloClient__Utils.bs.js:13)
    at useQuery (ApolloClient__React_Hooks_UseQuery.bs.js:51)
    at use (ApolloClient__React_Hooks_UseQuery.bs.js:72)
    at Module.app (curry.js:33)

I guess what it causes from this part of the compiled code.

module Ship = [%graphql
  {|
  query ship { shipRequests {
      id
      user_id
      species
      quantity
      created_at
    }
}
|}
];

function parse(value) {
  var value$1 = value.shipRequests; // throwing error!
  return {
          shipRequests: {
            __typename: value$1.__typename,
            id: value$1.id,
            user_id: value$1.user_id,
            species: value$1.species,
            quantity: value$1.quantity,
            created_at: value$1.created_at
          }
        };
}

In this case, Ship.use() alwasy throwing an error. I think this forces me to use the catching JS Exception which I am really not willing to use. Is there any workaround or a good way to avoid it?

[jfrolich]

Which client do you use? It's probably a client issue.

[jfrolich]

Ah from the error it looks like reason-apollo-client. Can you also share the schema? @jeddeloh

[jeddeloh]

Yeah, @mattdamon108, do you want to open an issue on reason-apollo-client? I only run data through the parse function if it's there, so this must be a case of having partial data. Coincidentally, I have a proposal out that would fix this issue: jeddeloh/rescript-apollo-client#45

In the meantime, maybe try setting your errorPolicy to None so you're not returning partial data along with errors?

  ApolloClient.(
    make(
      ~defaultOptions=
        DefaultOptions.make(
          ~query=
            DefaultQueryOptions.make(
              ~fetchPolicy=NetworkOnly,
              ~errorPolicy=None,
              (),
            ),
        ),
      ~cache=Cache.InMemoryCache.make(),
      ~link,
      (),
    )
  );

[mununki]

@jfrolich here's my query and schema

module Ship = [%graphql
  {|
  query { shipRequests {
      id
      user_id
      species
      quantity
      created_at
    }
}
|}
];

type Query {
  shipRequests: ship_request!
}

type ship_request {
  created_at: DateTime!
  id: Int!
  quantity: String!
  species: String!
  user_id: Int!
}

[mununki]

@jfrolich @jeddeloh I'm still not sure to what this issue belongs, the client.. or ppx..

According my schema, Query.shipRequests has a type ship_request!, it seems quite obvious that the function parse should looks like it. But, isn't it necessary to have a null checking inside?

function parse(value) {
  if(!value || !value.shipRequests) return  // something like this maybe?

  var value$1 = value.shipRequests;
  return {
          shipRequests: {
            __typename: value$1.__typename,
            id: value$1.id,
            user_id: value$1.user_id,
            species: value$1.species,
            quantity: value$1.quantity,
            created_at: value$1.created_at
          }
        };
}

[jfrolich]

What server do you use? It looks like value.shipRequests can never be null, is it violating the protocol? Or is it null because there are some errors?

[mununki]

@jfrolich I use apollo server with prisma. The case was caused by the authentication error actually. Yes, ship_request shouldn't be null so that I made a type in schema with !. But the case is happening in error handling side, before touching the ground to check the ship_request shouldn't be null with that parse function I guess.

let getUser = (req: ApolloServer.request) => {
  switch req.headers.authorization {
    | Some(authorization) => {
      try {
        authorization
        ->Js.String2.replace("Bearer ", "")
        ->verify(jwtSecret)
      } catch {
        | Js.Exn.Error(e) => {
          let name = e->Js.Exn.name->Belt.Option.getWithDefault("ErrorName")
          let message = e->Js.Exn.message->Belt.Option.getWithDefault("ErrorMessage")
          raise(ApolloServer.authenticationError(name ++ ": " ++ message))
        }
      }
    }
    | None => raise(ApolloServer.authenticationError("Authentication Required"))
  }
}

[jfrolich]

Yes if there is an error it's probably a bug in the client (it shouldn't try to parse the data).

[mununki]

@jfrolich fair enough. I opened an issue in client repo. And @jeddeloh mentioned there is upcomming PR to fix this. I'll close this issue. Thank you for your clarification and time.