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FHIR OperationDefinition

This operation extends the search capabilities of FHIR using a search profile called fhirPath, for use with all resource types.

This search profile allows the user to retrieve a set of FHIR resources from the server filtered by one or more FHIRPath expressions. Each expression is evaluated against each resource, returning a Boolean value which determines whether the resource will be included in the search result.

As per the FHIR search specification, multiple instances of the search parameter are combined using Boolean AND logic, and multiple expressions can be provided within a single search parameter and delimited by commas to achieve OR logic. In addition to this, FHIRPath boolean operators can be used within expressions.

Composite search parameters (using the $ notation) are not currently supported.

GET [FHIR endpoint]/[resource type]?_query=fhirPath&filter=[FHIRPath expression]...
POST [FHIR endpoint]/[resource type]/_search


The fhirPath named search query defines a single parameter:

  • filter [1..*] - (string) A FHIRPath expression that can be evaluated against each resource in the data set to determine whether it is included within the result. The context is an individual resource of the type that the search is being invoked against. The expression must evaluate to a Boolean value.

The named query is invoked using a parameter of _query with a value of fhirPath.

Parameters are passed in the query portion of the URL for GET requests, and can be passed either in the URL or in a application/x-www-form-urlencoded body for POST requests.


Any search request in FHIR returns a Bundle of matching resources.

Pagination links are included for responses which include a large number of resources. The number of resources returned in a single response is 100 by default this can be altered using the _count parameter.

See Search in the FHIR specification for more details.


Check out example search requests in the Postman collection:

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