how to add headers dynamically to CustomGraphQLClient executeQuery

[PandaGeek1024]

with old DefaultGraphQLClient, we can add headers dynamically while a request comes. This is designed this way because we only know some specific headers when client send a request to service.

Now we are migrating from DefaultGraphQLClient to CustomGraphQLClient, but unfortunately the RequestExecutor is only provided during CustomGraphQLClient creation. This means all headers has to be predefined and known beforehand.

is there a way to achieve dynamic headers attaching as below old implementation?

Old code:

@Bean(name = [CORE_PRODUCT_GRAPHQL_CLIENT])
fun coreGraphQLClient(): GraphQLClient {
      return DefaultGraphQLClient(url)
}

fun executeQuery(query: String, graphQLHeaders: GraphqlHeaderMaps? = null): GraphQLResponse {
	return graphQLClient.executeQuery(query, HashMap<String, List<String>>()) { url, headers, body ->
		val requestHeaders = HttpHeaders()
		headers.forEach(requestHeaders::put)

		graphQLHeaders?.forEach(requestHeaders::put)

		val exchange: ResponseEntity<String> = restTemplate.exchange(
			url, HttpMethod.POST, HttpEntity<Any?>(body, requestHeaders),
			String::class.java
		)
		HttpResponse(exchange.statusCodeValue, exchange.body)
	}
}

[PandaGeek1024]

any reponse? this is quite urgent to us

[PandaGeek1024]

hey guys, is there any update on this issue?

[PandaGeek1024]

@sjohnr would you be able to take a look?

[sjohnr]

@PandaGeek1024 I apologize for the long delay in looking at this issue. I missed your comment in a notification swarm. Have you looked at RestClientGraphQLClient as a potential solution? It seems to be exactly what you're looking for.

Note that Spring also provides an adapter for using RestClient with RestTemplate through RestClient.create(RestTemplate).

[PandaGeek1024]

@sjohnr i have take a look at RestClientGraphQLClient but I dont seem to find it has the ability to add http header during runtime?

[sjohnr]

Hi @PandaGeek1024. So it is tricky because RestClientGraphQLClient only accepts a headersConsumer, but it is possible. There are several possible approaches:

1. Pass headers from your custom service to a custom headersConsumer using a custom ThreadLocal
2. Use an existing ThreadLocal like Spring's RequestContextHolder to create a dynamic "request-aware" headersConsumer

Here's an example of the 2nd approach:

  @Configuration
  class GraphQLClientConfig {

      @Bean
      fun graphQLClient(): GraphQLClient {
          val restClient = RestClient.builder()
              .baseUrl("http://your-graphql-endpoint/graphql")
              .build()

          return RestClientGraphQLClient(restClient) { headers ->
              // Get the current HTTP request from Spring's RequestContextHolder
              val requestAttributes = RequestContextHolder.getRequestAttributes() as? ServletRequestAttributes
              val request: HttpServletRequest? = requestAttributes?.request

              if (request != null) {
                  // TODO: Logic for computing dynamic headers based on the incoming request
                  // 
                  // Example: Forward specific headers from incoming request
                  // request.getHeader("X-Tenant-Id")?.let { headers.add("X-Tenant-Id", it) }
                  // request.getHeader("Authorization")?.let { headers.add("Authorization", it) }
                  //
                  // Example: Compute headers based on request data
                  // val tenantId = request.getHeader("X-Tenant-Id")
                  // if (tenantId != null) {
                  //     val computedHeader = computeHeaderValue(tenantId)
                  //     headers.add("X-Custom-Header", computedHeader)
                  // }
              }
          }
      }
  }

If this doesn't help you move forward, can you please explain what type of information your service is receiving from the client? Specifically:

This is designed this way because we only know some specific headers when client send a request to service.

What information in the request are you receiving from the client? Is it a custom header or specific header value being passed? Is it only when a specific endpoint or URL is called? What headers are you populating in your executeQuery method?

[sjohnr]

Also, I forgot to mention: If you still want to use CustomGraphQLClient, you are not really required to create only a single instance as a @Bean. I think it would be perfectly fine to create one per request in order to capture the graphQLHeaders in your service. Here's an example that should be very close to what you're trying to do:

  @Service
  class MyGraphQLService(
      private val restTemplate: RestTemplate,
      private val objectMapper: ObjectMapper
  ) {
      private val url = "http://your-graphql-endpoint/graphql" // or use an @Value in constructor

      fun executeQuery(
          query: String, 
          graphQLHeaders: Map<String, List<String>>? = null
      ): GraphQLResponse {
          // Create a new client that captures graphQLHeaders
          val client = CustomGraphQLClient(url, { url, headers, body ->
              val requestHeaders = HttpHeaders()

              // Add default headers
              headers.forEach(requestHeaders::put)

              // Add dynamic headers (captured from the method parameter)
              graphQLHeaders?.forEach(requestHeaders::put)

              // Execute HTTP request
              val exchange = restTemplate.exchange(
                  url,
                  HttpMethod.POST,
                  HttpEntity(body, requestHeaders),
                  String::class.java
              )
              HttpResponse(exchange.statusCode.value(), exchange.body)
          }, objectMapper)

          return client.executeQuery(query)
      }
  }

[rostislavosvald-ataccama]

Hi, I am having the same issue. I would like to pass auth header to the http request in my CustomGraphQLClient. The solutions you described are definitely possible, but I have some reservations for them:

1. Creating client per request seems unnecessarily wasteful. Potentially a lot of objects being created and collected by GC
2. Using thread locals can break if multi-threading is in play. Seems unnecessarily brittle.

I will concede these reservations are not necessarily a big deal, but in my opinion it would be nice to be able to pass custom request header directly to executeQuery method without having to resort to these sort of hacks.