FHIR Chat · Search resources based on extension values

Stream: hapi

Topic: Search resources based on extension values

Markku Nikkanen (Jul 15 2020 at 08:52):

Hello,

I have some extensions in Encounter FHIR object. How do I implement "query matcher" against extension? Any reference implementation available?

Br,
Markku

Grahame Grieve (Jul 15 2020 at 10:11):

what's a 'query matcher'?

Markku Nikkanen (Jul 16 2020 at 05:33):

Grahame Grieve said:

what's a 'query matcher'?

By "query matcher" I mean a way of doing queries against attributes in an extension. As an example, how to query Encounters having valueString "checkin"?

{
  "resourceType": "Encounter",
  "extension": [
    {
      "url": "http://something.com/fhir/#currentQueueStatus",
      "valueString": "checkin"
    }
  ],
...
}

James Agnew (Jul 16 2020 at 09:36):

You need to create a custom search parameter. This blog goes over the process: https://blog.smilecdr.com/2017/02/08/custom-search-parameters-in-hapi-fhir/

Markku Nikkanen (Jul 17 2020 at 09:30):

James Agnew Thank you for this information. I got it working in Unit Test by creating SearchParam object before adding any test data to h2 database.

  private static void initialiseTestDatabase() throws ParseException {
    client.create().resource(createSearchParam()).execute();

    // Location with room
    Location l = LocationFactory.create();
    IIdType locationId = client.create().resource(l).execute().getId();
...

What would be proper way to create SearchParam object in hapi-fhir-jpaserver-starter fork? I tried create object at the very end of the JpaRestfulServer initialise with no luck:

protected void initialize() throws ServletException {
...
    IGenericClient client = ctx.newRestfulGenericClient(serverAddress);
    client.create().resource(createSearchParam()).execute();

It did not work. It seems you cannot call create inside initialise method:

ca.uhn.fhir.rest.client.exceptions.FhirClientConnectionException: Failed to retrieve the server metadata statement during client initialization. URL used was http://localhost:8888/fhir/metadata
    at ca.uhn.fhir.rest.client.impl.RestfulClientFactory.validateServerBase(RestfulClientFactory.java:312)

Should I start listening Spring or Jetty's lifecycle events that are called after initialisation is ready?

Markku Nikkanen (Jul 17 2020 at 09:52):

(deleted)

Markku Nikkanen (Jul 20 2020 at 17:12):

I did not get servlet approach operating. I think that the issue is that no one is listening port 8080 when servlets is being initialised.

~/repos/my-fhir-service/src/main/webapp/WEB-INF/web.xml

    <servlet>
        <servlet-name>fhirServlet</servlet-name>
        <servlet-class>ca.uhn.fhir.jpa.starter.JpaRestfulServer</servlet-class>
        <load-on-startup>2</load-on-startup>
    </servlet>
    <servlet>
        <servlet-name>myMigration</servlet-name>
        <servlet-class>my.project.MyMigration</servlet-class>
        <load-on-startup>3</load-on-startup>
    </servlet>

public class MyMigration extends RestfulServer {
  @Override
  protected void initialize() throws ServletException {
    String serverAddress = HapiProperties.getServerAddress();
    IGenericClient client = ctx.newRestfulGenericClient(serverAddress);
    client.create().resource(createExtensionSearchParam()).execute();
}

Is there any events (Pointcut?) that are sent when JpaRestfulServer initialisation is ready and servlet is listening in port 8080?

https://smilecdr.com/hapi-fhir/apidocs/hapi-fhir-base/ca/uhn/fhir/interceptor/api/Pointcut.html

Or would it be better to have a separate project that runs all sort of migrations to database like ads the Search Params? Perhaps there is already something ready made frameworks for this e.g.

https://hapifhir.io/hapi-fhir/docs/server_jpa/upgrading.html