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FHIR Validator

A Transform Custom node that validates an inbound FHIR resource against a FHIR server's $validate operation and forwards it unchanged only when it passes. Anything else stops the node.

Published in the Linkiir FHIR Adapters catalog. Subscribe to that catalog to add this adapter to your grid — see Adapter Catalogs.

What it does​

The node reads the inbound FHIR JSON, sends it to a FHIR server's $validate operation, and looks at the OperationOutcome that comes back to decide the verdict:

Receive JSON  →  Validate  →  Pass or Stop
  • Valid (including valid with only warnings or information) → forward the original bytes, unchanged, to the next node.
  • Invalid, or indeterminate → stop the node with an error and forward nothing.

It fails closed. An invalid resource, a timeout, an HTTP error, a malformed response, or a profile the server cannot resolve all stop the node, so a resource that was not cleanly validated never reaches the next node. Stopping is done by raising an error, which hands the failure to Linkiir's own error handling.

The FHIR server is the authority. A 200 response is not treated as a pass on its own — the returned OperationOutcome decides, because $validate can return 200 for a resource that has errors.

The resource type is read from the resource itself, so one node validates Patient, Observation, Encounter, and others without any per-type setting.

Where it fits​

Put it straight after the FHIR Resource Creator, so only validated resources move on.

FHIR Resource Creator  →  FHIR Validator  →  a FHIR server, a file, or your next node

Set it up​

  1. Add the FHIR Validator node to a workflow, or open the supplied one, and connect the node producing FHIR JSON to its input.
  2. Click Edit and set FHIR Server URL to a FHIR base URL. For synthetic development testing you can use https://hapi.fhir.org/baseR4.
  3. Optionally set FHIR Profile to a profile canonical URL, but only if that profile is installed on the server.
  4. Connect the node that should receive the validated resource to its output.
  5. Save, then send one message through with Run Test on the upstream node, and start the nodes.
Do not send real patient data to the public server

https://hapi.fhir.org/baseR4 is a public development server and a DEV example only. In production, leave the server URL unset until an administrator selects a PHI-approved endpoint, and never point it at the public server for real patient data.

Configuration reference​

Two settings, and that is the whole node.

FieldTypeDefaultPurpose
FHIR Server URLstring(empty)The FHIR base URL whose $validate operation to call, with no trailing resource path. Required
FHIR Profilestring(empty)Optional profile canonical URL to validate against. Leave empty to validate against the resource's base definition

TLS verification is always on and the request timeout is an internal default (15 seconds). Neither is exposed, deliberately — there is no switch to weaken transport security in this catalog.

If a profile is set but the server cannot resolve it, the resource is not forwarded. There is no silent fall back to base validation, so a requested profile is either honored or the node stops.

The samples​

The node ships a matched pair you can feed with Run Test to see both paths:

SampleWhat happens
patient_valid.jsonA realistic Patient with a narrative. The server reports no issues, and the node forwards it
patient_invalid.jsonThe same Patient with an element that is not part of the FHIR spec. The server returns an error, and the node stops

Verify it worked​

  • Feeding patient_valid.json logs FHIR Validator: valid, forwarded. and the downstream node receives the resource unchanged.
  • Feeding patient_invalid.json stops the node with FHIR validation failed, and nothing is forwarded.
  • The log line summarizes issues by severity — errors and warnings are listed, and routine information-level notes from the server are reported as a count rather than printed in full.

If it didn't work​

SymptomCauseFix
no FHIR Server URL is configured at runFHIR Server URL is emptySet a FHIR base URL and try again
Every resource stops with a timeout or HTTP errorThe server URL is wrong or unreachableCheck the URL is a FHIR base with no trailing resource path, and that the server is reachable from the grid
A resource you expected to pass stops on a profileThe FHIR Profile is not installed on the server, so it cannot be resolvedInstall the profile on the server, or clear the field to validate against the base definition
A resource passes elsewhere but fails hereThis server enforces a rule or profile the other did notConfirm the two servers and profiles match; the validating server is the authority
The log line is longThe server returned many issuesOnly errors and warnings are listed and the line is capped; information-level notes are counted, not printed

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