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Retrieving the patient's ehrId

When a patient is registered with an openCDR, a 'subjectId (normally a real-word identifier like an National identifier e.g. NHS number, CHI number in the UK) or hospital MRI) is submitted by a POST /ehr | create EHR from SubjectId call.

A top-level openEHR EHR object is then created in the CDR along with a unique internal ehrId identifier for that patient.

Most openCDR API calls require an 'ehrId' to identify the correct patient, so normally the first activity required if interacting with a patient record is to retrieve their ehrId, and then often to cache that identifier so it can be used for subsequent calls, until a new patient is being accessed.

GET /ehr - retrieve ehr from subjectId/subjectNamespace

Parameters
subjectId

This is the external identifier by which the patient is known within the CDR. It is normally a real-word identifier like an NHS number, CHI number or Hospital 'MRI' number, and will have been supplied to the CDR when the patients' EHR object was created in the datastore.

Example value : 9999999000

subjectNamespace

This is just a unique string used to identify the numbering scheme used for the subjectId. It will commonly be some sort of URI such as jm.gov.nin and will have been agreed at national level.

Example value : jm.gov.nin

    --curl location \
    --request GET '/ehr/?subjectId=https://cdr.code4health.org/rest/openehr/v19999999000&subjectNamespace=uk.nhs.nhs_number' \
    --header 'Content-Type: application/json' \
    --header 'Accept: application/json' \
    --header 'Authorization: Basic YTgxZjQ3YzYtYTc1Ny00ZTM0LWI2NDQtM2NjYzYyYjRhMDFjOiQyYSQxMCQ2MTlraQ=='
    --header 'PREFER: return=minimal' \

    var axios = require('axios');

    var config = {
    method: 'get',
    url: 'https://cdr.code4health.org/rest/openehr/v1/ehr?subject_id=9999999000&subject_namespace=uk.nhs.nhs_number',
    headers: { 
        'Accept': 'application/json', 
        'Content-Type': 'application/json', 
        'PREFER': 'return=minimal', 
        'Authorization': Basic YTgxZjQ3YzYtYTc1Ny00ZTM0LWI2NDQtM2NjYzYyYjRhMDFjOiQyYSQxMCQ2MTlraQ=='
    }
    };

    axios(config)
    .then(function (response) {
    console.log(JSON.stringify(response.data));
    })
    .catch(function (error) {
    console.log(error);
    });

import requests

    url = "https://cdr.code4health.org/rest/openehr/v1/ehr?subject_id=9999999000&subject_namespace=uk.nhs.nhs_number"

    payload = {}
    headers = {
    'Accept': 'application/json',
    'Content-Type': 'application/json',
    'PREFER': 'return=minimal',
    'Authorization': 'Basic YTgxZjQ3YzYtYTc1Ny00ZTM0LWI2NDQtM2NjYzYyYjRhMDFjOiQyYSQxMCQ2MTlraQ=='
    }

    response = requests.request("GET", url, headers=headers, data = payload)

    print(response.text.encode('utf8'))

Response

An openCDR will give a 200 response code and this structure.

The ehrId that you need to capture is ehr_id.value item in the response.

Hint

You may want to consider caching this for the session, so that it can be used for a number of subsequent calls.

{
    "_type": "EHR",
    "system_id": {
        "_type": "HIER_OBJECT_ID",
        "value": "4cce5a07-be4d-4318-a94f-3b8401853a20"
    },
    "ehr_id": {
        "_type": "HIER_OBJECT_ID",
        "value": "5dd03bc9-4419-4981-8798-ff4dda8ee9de"
    },
    "time_created": {
        "_type": "DV_DATE_TIME",
        "value": "2020-07-21T09:00:24.977Z"
    },
    "ehr_status": {
        "_type": "EHR_STATUS",
        "uid": {
            "_type": "HIER_OBJECT_ID",
            "value": "09bcd903-1565-44db-9087-2ff5e5bc7194::4cce5a07-be4d-4318-a94f-3b8401853a20::1"
        },
        "subject": {
            "_type": "PARTY_SELF",
            "external_ref": {
                "_type": "PARTY_REF",
                "id": {
                    "_type": "HIER_OBJECT_ID",
                    "value": "9999999000"
                },
                "namespace": "uk.nhs.nhs_number"
            }
        },
        "is_queryable": true,
        "is_modifiable": true
    }
}