FHIR search by extension

Question

How can I search for extension values in FHIR? Is SearchParameter registration necessary for searching for the extension? Any help with an example would be great. I have been trying with my own FHIR server (https://github.com/Microsoft/fhir-server) using mothersMaidenName after SearchParameter registration but it gives all the Patients from the server.

Update

I have this JSON set as Extension for Patient Resource.

{
  "extension": [
    {
      "url": "http://hl7.org/fhir/SearchParameter/patient-extensions-Patient-mothersMaidenName",
      "valueString": "trial"
    }
  ]
}

The SearchParameters registration is done like this (these are from https://www.hl7.org/fhir):

{
  "resourceType": "SearchParameter",
  "id": "e3f10e54-f558-49bb-8732-faee3a4dda8d",
  "url": "http://hl7.org/fhir/SearchParameter/patient-extensions-Patient-mothersMaidenName",
  "version": "3.6.0",
  "name": "mothersMaidenName",
  "status": "draft",
  "experimental": true,
  "code": "mothersMaidenName",
  "base": [
    "Patient"
  ],
  "type": "string",
  "description": "Search based on patient's mother's maiden name",
  "expression": "Patient.extension(http://hl7.org/fhir/SearchParameter/patient-extensions-Patient-mothersMaidenName)",
  "xpathUsage": "normal"
}

Hi! Where did you find that SearchParameter definition? It contains an error, so if you send us the link, I can report it to have it fixed. — Mirjam Baltus

Lloyd McKenzie Lloyd McKenzie · Accepted Answer · 2018-11-26T15:51:56

Two steps are required: first, you need to define a custom SearchParameter that searchs on the element you wish in the way you wish. Second, all relevant servers must be manually changed (i.e. have code written) to support the new search parameter.

FHIR search by extension

3 Answers