Global State

Global State allows us to define properties on a per-request basis to be made available to all resolvers and middleware.

Initializing Global State

We can add Global State using the SetProperty method on the OperationRequestBuilder. This method takes a key and a value as an argument. While the key needs to be a string the value can be of any type.

Using an interceptor allows us to initialize the Global State before the request is being executed.

public class HttpRequestInterceptor : DefaultHttpRequestInterceptor
{
    public override ValueTask OnCreateAsync(HttpContext context,
        IRequestExecutor requestExecutor, OperationRequestBuilder requestBuilder,
        CancellationToken cancellationToken)
    {
        string userId =
            context.User.FindFirst(ClaimTypes.NameIdentifier)?.Value;

        requestBuilder.SetProperty("UserId", userId);
        // requestBuilder.SetProperty("IntegerValue", int.Parse(userId));
        // requestBuilder.SetProperty("ObjectValue", new User { Id = userId });

        return base.OnCreateAsync(context, requestExecutor, requestBuilder,
            cancellationToken);
    }
}

Learn more about interceptors

Accessing Global State

We can access the Global State in our resolvers like the following.

public class Query
{
    public string Example1([GlobalState("UserId")] string userId)
    {
        // Omitted code for brevity
    }

    public string Example2([GlobalState("ObjectValue")] User user)
    {
        // Omitted code for brevity
    }
}

The GlobalStateAttribute accepts the key of the Global State value as an argument. An exception is thrown if no Global State value exists for the specified key or if the value can not be coerced to the type of the argument.

It's a good practice to create a new attribute inheriting from GlobalStateAttribute.

public class UserIdAttribute : GlobalStateAttribute
{
    public UserIdAttribute() : base("UserId")
    {

    }
}

public class Query
{
    public string Example([UserId] string userId)
    {
        // Omitted code for brevity
    }
}

Last updated on 2024-11-20 by Michael Staib