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2.44 Resource OperationOutcome - Content

FHIR Infrastructure Work Group

Maturity Level : 5 N

Trial Use Normative (from v4.0.0)

Compartments : Not linked to any defined compartments

This page has been approved as part of an ANSI standard. See the Infrastructure Package for further details.

A collection of error, warning warning, or information messages that result from a system action.

This resource is referenced by GuidanceResponse and MessageHeader

2.44.3 Resource Content

 

Alternate See the Profiles & Extensions and the alternate definitions: Master Definition ( XML , + JSON ), , XML Schema / Schematron (for ) + JSON Schema , ShEx (for Turtle ) + see the extensions & the dependency analysis

2.44.3.1 Terminology Bindings

Path	Definition	Type	Reference
OperationOutcome.issue.severity	How the issue affects the success of the action.	Required	IssueSeverity
OperationOutcome.issue.code	A code that describes the type of issue.	Required	IssueType
OperationOutcome.issue.details	A code that provides details as the exact issue.	Example	Operation Outcome Codes OperationOutcomeCodes

2.44.4 Using Operation Outcome Resources

On the RESTful interface, operation outcome resources are only relevant when a level of computable detail is required that is more granular than that provided by the HTTP response codes. This granularity could include:

• more detail about the location of an issue
• the ability to identify multiple distinct issues
• provision of finer error codes that connect to known business failure states

Operation outcomes returned SHOULD be in alignment with the HTTP response code. For example, if the HTTP code indicates a failure (300+), at least one of the issues should have a severity of "error", "error", indicating the reason for the failure.

Operation outcomes must include at least one issue. See the All OK example for a template for an operation that returns no errors.

2.44.5 Using the Location Element Expression

Each issue in an operation outcome may SHOUD have an expression that reports a location reported. Systems that create operation outcomes SHOULD populate for the location of an error. issue. A correctly propulated location populated expression can allow client systems to:

• Connect return errors with the appropriate UI widget
• Route errors to the corect correct application or system log
• Develop more intelligent testing applications

In order to support these kinds of usages, this applications need to use the location expression element consistently. Applications can use the location expression element to refer to a location inside a resource, or some location in the HTTP request (when appropriate).

2.44.5.1 Reporting Errors in Resources

While resources may be represented in XML, JSON, or other forms, error Error locations are always reported using a simplified XPath notation: <location value="/f:Patient/f:identifier"/> The XPath must use the FHIR standard XPath prefixes f: and h: FHIRPath for the FHIR and XHTML namespaces respectively. The XPath here can be used to automatically find the relevant XML element in a resource if the resource is represented in XML. Because resources are often represented statement in JSON, and because applications will often process the XPath directly (e.g. expression element. In addition to determine the relevant widget), the XPath statement must be simple. Specifically, simplified FHIRPath restrictions, the XPath expression SHALL only not contain element names and repetition indicators. So this is a .resolve() function. These examples are legal:

<location value="/f:Patient/f:identifier[2]/f:label"/>

 <expression value="Patient.identifier"/>

  "expression" : "Patient.identifier[2].value"

but this is not:

<location value="/f:Patient/f:identifier[f:system/@value='http://example.com/mrn']/f:label"/>

  "expression" : "Patient.identifier.where(system.value='http://example.com/mrn').value"

Because the Xpath is required to be simple, it can be converted to JsonPointer by dropping the namespace prefixes, and correcting for array offsets. The XPaths above have these equivalent JsonPointer representations: Patient/identifier Patient/identifier/2/label Note that correcting for array offsets may require knowledge of which elements are Arrays in JSON. It is also possible to convert the XPath statements to JsonPath, though there is no single standard for JsonPath.

2.44.5.2 2.44.5.1 Reporting Errors in the HTTP Headers

Servers may also need to report errors in the HTTP headers - especially query parameters when processing searches. Errors are reported using a case sensitive location expression that has two parts, a fixed "http" "http" and the header or query parameter name separated by a ".". ".". Some examples:

Location Expresson	Description
http.name:exact http.code	A reference to the search parameter "name" "code"
http."name:exact"	A reference to the search parameter "name" with the modifier ":exact" ":exact"
http.Authorization	A reference to the Authorization header - perhaps to indicate that it is missing, and some form of authentication is required.

This specification follows the convention that HTTP headers start with an uppercase character, and URL parameters start with a lowercase character. Implementations are encouraged to follow this convention, so that no name collisions occur.