Merging two patients

[thetestautomator]

Hello together,
I am trying to merge two patients using the endpoint ".../Patient/$merge". In Postman everything works fine but in the code I am not able to get this working. I tried different things but none of them worked. The current implementation always tells me "Invalid request. Query parameter sourcePatientId is missing."
Can you please help and tell me what I am doing wrong.

This is the current implementation (using net9.0, Hl7.Fhir.R4 version 5.12.2)

string baseURL = "...";
string targetPatientID = "123-234-5";
string sourcePatientID = "1234-4321-1";
FhirClientsettings settings = new(); // added some headers for auth, etc.
FhirClient client = new(baseURL, settings);

var parameters = new Parameters
{
    { "sourcePatientId", new FhirString(patSource) },
    { "targetPatientId", new FhirString(patTarget) }
};

var uri = new Uri($"{baseUrl}/Patient/$merge", UriKind.Absolute);
Resource mergeResult = await client.OperationAsync(uri, parameters);

[alexzautke]

@thetestautomator On the first look this doesn’t seem wrong to me. Have you tried serializing the Parameters resource to see if that looks correct to you?

[thetestautomator]

I added some logging to the request handler and saw that the parameters are not added to the URI (=> /Patient/$merge?sourcePatientId=123&targetPatientId=456) but as a body. And therefore, of course it's a bad request.
What is sent is:
URI = .../api/fhir/v1/Patient/$merge?_format=json
Method = POST
Body = {"resourceType":"Parameters","parameter":[{"name":"sourcePatientId","valueString":"123"},{"name":"targetPatientId","valueString":"456"}]}

Is there a possibility to add the parameters not as a body? Or would the only way be a workaround to add the IDs directly to the URI and not to the method?

[thetestautomator]

What works is:

var mergeURI = new Uri($"{baseURL}Patient/$merge?sourcePatientId={patSource}&targetPatientId={patTarget}", UriKind.Absolute);
// the empty parameters are needed otherwise it will throw a nullreference exception
Resource mergeResult = await client.OperationAsync(mergeURI, []);

[alexzautke]

There should be a useGet parameter on the operation method which turns the POST into a GET

[thetestautomator]

The issue arose because the request needed to be a POST method without a body:
POST {baseURL}Patient/$merge?sourcePatientId={patSource}&targetPatientId={patTarget}

However, the OperationAsync method included the parameters in the body instead of appending them to the URI - which I expected from the name. That was what confused me.

[andrzejskowronski]

Well, yes, I don't think it is usual to pass query arguments while still making a post request, usually you want query arguments in get and body in post, so that is what the SDK api does.
If you want the behavior as you specify indeed you'd have to use the snippet you provided, building the url yourself and not providing a body for us to serialize.

[thetestautomator]

Alright, then I will implement it this way.
Thank you for the quick support!

[alexzautke]

Also are you trying in Postman to use a GET or a POST request?

[thetestautomator]

It should be a POST

[ewoutkramer]

Or add the useGet argument to the OperationAsync call and see what happens.