FHIR RESTful URL Anatomy

A FHIR REST URL follows this pattern:

{base_url}/{resourceType}/{id}/{operation | sub-resource}?{parameters}

Segment	Required	Example	Notes
Base URL	Yes	https://hapi.fhir.org/baseR4	The FHIR server's root. Configure as the Endpoint URL on the Web Service Connection.
Resource type	Yes	Patient, Observation, MedicationRequest	Full list at hl7.org/fhir/R4/resourcelist.html.
Resource ID	When operating on a single instance	Patient/12345	The server-assigned ID for one resource.
Sub-resource	Optional	Patient/12345/Observation	Resources scoped under the parent. Not every server exposes every sub-resource.
Operation	Optional	$everything, $validate, $document	Operations begin with $. See hl7.org/fhir/R4/operationslist.html for the standard set. Servers may add their own.
Query parameters	Optional	?name=Smith&birthdate=1970-01-01	Search parameters and modifiers. See below. Each resource page on hl7.org lists the parameters that resource supports.

Examples

GET  https://hapi.fhir.org/baseR4/Patient/12345
GET  https://hapi.fhir.org/baseR4/Patient/12345/$everything
GET  https://hapi.fhir.org/baseR4/Patient?name=Smith&birthdate=1970-01-01
POST https://hapi.fhir.org/baseR4/Patient
PUT  https://hapi.fhir.org/baseR4/Patient/12345

In QIE the URL pattern is set on the REST Web Service Sender. Node tags substitute message values into the URL at call time, for example https://hapi.fhir.org/baseR4/Patient/{PID-3} resolves the patient ID from the inbound HL7 message.

Search parameter prefixes

Prefixes change how a parameter value is compared. They apply to date, number, and quantity parameters. The default (no prefix) is eq.

Prefix	Meaning	Example	Description
eq	Equal	birthdate=eq2000-01-01	Exact match. Default if no prefix is given.
ne	Not equal	birthdate=ne2000-01-01	Excludes records with that value.
gt	Greater than	birthdate=gt2000-01-01	After the supplied value.
lt	Less than	birthdate=lt2000-01-01	Before the supplied value.
ge	Greater or equal	birthdate=ge2000-01-01	On or after the supplied value.
le	Less or equal	birthdate=le2000-01-01	On or before the supplied value.
sa	Starts after	birthdate=sa2000-01-01	Date range starts after, and is more lenient than gt.
eb	Ends before	birthdate=eb2000-01-01	Date range ends before, and is more lenient than lt.
ap	Approximately	birthdate=ap2000-01-01	Server-defined fuzzy match around the value.

Search modifiers

Modifiers attach to the parameter name with a colon. They change how the parameter is interpreted (rather than how the value is compared).

Modifier	Meaning	Example	Description
:exact	Exact string match	name:exact=Smith	Matches Smith only, not smith or Smyth. Without this modifier most servers do a case-insensitive starts-with match.
:contains	Substring match	name:contains=mit	Matches Smith, Mitchell, etc.
:text	Search human-readable text	code:text=heart	Finds resources whose code element has the substring in its text/display.
:missing	Field exists / does not exist	gender:missing=true	Returns resources where the named field is absent. false returns resources where it is present.
:not	Negation	code:not=12345	Excludes matches.

Each resource page on hl7.org publishes the search parameters it supports along with the types that determine which prefixes and modifiers are valid. For example, Patient search parameters appears at the bottom of the Patient resource page.