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kotlinlang

Hi, has anyone implemented a solution for access token expired or in general access denied that doesn't rely on gql returning http code 401?
My current solution is to handle the token expired error in each GQL request. But is prompt to errors since new devs may forget to add the error in the GQL query.
Perhaps is there a way of doing GQL query inheritance? Where I could have a based query with this error and not having to repeat it in every query.

Add an interceptor that checks `response.errors` (assuming this is where the server signals the expired token) and retry the downstream chain

&gt; since new devs may forget to add the error in the GQL query.
Wait, the error is actually part of your schema looks like?

But even if it's part of your schema, there must be a `response.errors` entry for missing data

Yes correct. The service sends a list of errors. 
I have to take a look into the ApolloInterceptor, I haven't heard of it. Right now we use an okhttp Authenticator that relies on the service sending back the 401. But we are evaluating to move from the 401 status code and okhttp Authenticator to a pure gql response error handler. Which will take care of refreshing the token.

I think `ApolloInterceptor` is what you want. It's like OkHttp `Interceptor` but works at the GraphQL layer so you'll have access to `response.errors`

If you're using the normalized cache, make sure to call `.addInterceptor()` after `.normalizedCache()` to only run your interceptor if network is required

```class ReauthApolloInterceptor : ApolloInterceptor {

    override fun &lt;D : Operation.Data&gt; intercept(
        request: ApolloRequest&lt;D&gt;,
        chain: ApolloInterceptorChain
    ): Flow&lt;ApolloResponse&lt;D&gt;&gt; = chain.proceed(request).map { response -&gt;

        if (!request.operation.requiresAuth()) {
            return@map response
        }

        val authorised = response.errors.doesNotContainUnAuthorised()

        if (authorised) {
            return@map response
        }

        val newToken = getNewToken()

        chain.proceed(request.newBuilder().addNewToken(newToken).build())
    }
}```
Some half-working code to help you (sorry can't quite share exact code because it's private but this is the general idea)

I appreciate it, thanks so much. That's super helpful :slightly_smiling_face: