How can I execute an instance query in graphql-fhir? - hl7-fhir

Question

This issue is migrated from a question on our Github account because we want the answer to be available to others. Here is the original question:
Hello,
Following is the InstanceQuery I tried
http://localhost:3000/3_0_1/Questionnaire/jamana/$graphql?query={id}
I am receiving back response as Cannot query field \"id\" on type \"Questionnaire_Query\"
So what is the right format I should try ?
https://build.fhir.org/graphql.html has a sample as http://test.fhir.org/r3/Patient/example/$graphql?query={name{text,given,family}}.Its working in their server. I cannot get the response When I try similarly in our graphql-fhir.

Answer 1

Original answer from Github:
We are using named queries since we are using express-graphql. I do not believe that is valid syntax. Also, the url provided does not seem to work, I just get an OperationOutcome saying the patient does not exist, which is not a valid GraphQL response.
Can you try changing your query from:
http://localhost:3000/3_0_1/Questionnaire/jamana/$graphql?query={id}
to this:
http://localhost:3000/3_0_1/Questionnaire/jamana/$graphql?query={Questionnaire{id}}
When writing the query, you need to provide the return type as part of the instance query. You should get a response that looks like similar to this(if you have implemented your resolver you will have data and not null):
{
"data": {
"Questionnaire": {
"id": null
}
}
}
and from a later comment:
If you are getting null then you are doing it correctly, but you haven't wrote a query or connected it to a data source. You still need to return the questionnaire in the resolver.
Where you are seeing this:
instance: {
name: 'Questionnaire',
path: '/3_0_1/Questionnaire/:id',
query: QuestionnaireInstanceQuery,
},
You are seeing the endpoint being registered with an id parameter, which is different from a GraphQL argument. This is just an express argument. If you navigate to the questionnaire/query.js file, you can see that the QuestionnaireInstanceQuery query has a different resolver than the standard QuestionnaireQuery. So in your questionnaire/resolver.js file, if you want both query and instance query to work, you need to implement both resolvers.
e.g.
// This is for the standard query
module.exports.getQuestionnaire = function getQuestionnaire(
root,
args,
context = {},
info,
) {
let { server, version, req, res } = context;
// Do query and return questionnaire
return {};
};
// This one is for a questionnaire instance
module.exports.getQuestionnaireInstance = function getQuestionnaireInstance(
root,
args,
context = {},
info,
) {
let { server, version, req, res } = context;
// req.params.id is your questionnaire id, use that for your query here
// queryQuestionnaireById does not exist, it is pseudo code
// you need to query your database here with the id
let questionnaire = queryQuestionnaireById(req.params.id);
// return the correct questionnaire here, default returns {},
// which is why you see null, because no data is returned
return questionnaire;
};