core.replacequeryvariables

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replaceQueryVariables() function

Replaces prefetch query variables with values from the context or user profile.

A prefetch token is a placeholder in a prefetch template that is *replaced by information from the hook's context* to construct the FHIR URL used to request the prefetch data.

Prefetch tokens MUST be delimited by {{ and }}, and MUST contain only the qualified path to a hook context field or one of the following user identifiers: userPractitionerId, userPractitionerRoleId, userPatientId, or userRelatedPersonId.

Note that the spec says:

> Individual hooks specify which of their context fields can be used as prefetch tokens. > Only root-level fields with a primitive value within the context object are eligible to be used as prefetch tokens. > For example, {{context.medication.id}} is not a valid prefetch token because it attempts to access the id field of the medication field.

Unfortunately, many CDS Hooks services do not follow this rule. Therefore, this implementation allows access to nested fields.

Signature:

export declare function replaceQueryVariables(user: CdsUserResource, context: Record<string, unknown>, query: string): string;

Parameters

Parameter	Type	Description
user	CdsUserResource	The user resource.
context	Record<string, unknown>	The CDS request context.
query	string	The prefetch query template.

Returns:

string

The prefetch query with variables replaced.