Returning Partial Success, with error message.

[bo55vxr]

In my Graph QL query handler, it has to pull together data from multiple APIs by using Field Resolvers.

If any one of the field resolvers fail to get a response, I still need to send back what has been successful but want to be able to advise the consumer that a particular (sub) data set is not available, in the errors object.

example.

Customer
  Name
  Address
  *Orders
     OrderID
     TotalValue

If the query is unable to retrieve the orders for this customer, then, still return the customer details, but with the Order property of null or Enumerable.Empty<Order> but then I want to add a message to the error object.

As the main query returns Task<Customer>, can I also indicate that there are errors also, to build into the response.

[bo55vxr]

Well, I'll answer my own question - You can build an error within the resolver and attach it to the request context.

descriptor.Field(fld => fld.Orders)
          .Resolve(async (cntx, ct) =>
          {
              try
              {
                  // Retrieve the customer's orders
                  return await _ordersProvider.Query(cntx.Parent<Models.Customer>().CustomerId);
              }
              catch
              {
                  // Unable to retrieve orders
                  cntx.ReportError(ErrorBuilder.New()
                                    .SetMessage("Unable to retrieve Customer's orders")
                                    .Build()
                      );
                  return Enumerable.Empty<Order>();
              }
          });