typesafe-client-accessing-metadata-of-responses.md

Accessing Metadata of GraphQL Responses with TypesafeResponse

The TypesafeResponse class provides a wrapper around the "data" field of GraphQL responses, along with additional metadata such as errors, extensions, and transport metadata. Here are the methods you can use to access each type of metadata:

Transport metadata

use getTransportMeta() method to retrieve a map of transport metadata associated with the response.

[NOTE] Note that the transport metadata referred to in the context of HTTP requests and responses is commonly found in the headers of the communication. Therefore, the getTransportMeta() method mentioned here can be used to retrieve a map of HTTP headers.

Extensions

use getExtensions() method to retrieve a JsonObject of response extensions. The method returns a JSON object that represents the response extensions.

Data

use get() method to retrieve the data object. The method returns the data object if it exists and there are no errors. If there are errors, it throws a NoSuchElementException with the error message.

Errors

use getErrors() method to retrieve a list of GraphQL errors. The method returns a list of errors if there are errors and no data object. If there is a data object, it throws a NoSuchElementException with the error message.

[NOTE] Note that the get() method assumes that the response has a data object, and will throw an exception if there are errors without a data object. If you want to check for errors before retrieving the data object, use the hasErrors() method, which returns true if there are errors and false otherwise.

You can use these methods to access and process the metadata of GraphQL responses returned by the TypesafeResponse class.

Let's say you want to get as a client extensions from the GraphQL response. First of all you will need to modify your GraphQLClientApi interface to have your return type class (in this case SuperHero) wrapped with TypesafeResponse class. I.e. your GraphQLClientApi interface could look like this:

import examples.typesafeclient.SuperHero;
import io.smallrye.graphql.client.typesafe.api.TypesafeResponse;

@GraphQLClientApi
public interface SuperHeroApi {
    // ...
    TypesafeResponse<SuperHero> findSuperHeroByName(String name);
    // ...
}

[NOTE] Note that you can have TypesafeResponse<T> only as a result (return) type of your query. Unlike ErrorOr the class cannot wrap individual fields. If that is the case IllegalArgumentException will be thrown.

And now to get extensions from the response your code will look like something like this:

    @Inject
    SuperHeroApi client;

    TypesafeResponse<SuperHero> superheroResponse = client.findSuperHeroByName("Batman");
    // returns the "data" field
    SuperHero superhero = superhero.get();
    // returns the "extensions" field
    JsonObject extensions = superhero.getExtensions();