Hl7.Cql.Packager

HL7 CQL Packager

A .NET tool that packages CQL, ELM, and build outputs into a FHIR Library resource.

Overview

The HL7 CQL Packager performs the following steps:

1. CQL to ELM Conversion: Converts CQL files into ELM JSON files.
2. ELM to C#: Converts ELM JSON files into Linq.Expressions, then translates these expressions into C# code. Each ELM file is converted into a class, with each function within that file becoming a public method in the class.
3. C# to .NET DLL Compilation: Compiles the generated C# code into a single assembly per ELM file.
4. Packaging to FHIR Libraries/Measures: Packages the assembly (and optionally the original CQL, ELM, and C# source code) into a FHIR Library resource, creating one resource per original ELM file. Where applicable, FHIR Measure resources are also generated.

Limitations

The tool does not convert CQL into ELM yet. You need to use the existing Java-based tooling for this conversion.

Getting Started

Installation

Install the packager tool globally using the following command:

dotnet tool install Hl7.Cql.Packager --global --prerelease

Note: The --prerelease option is required because only prerelease versions are currently available.

Usage

Get help for the command line tool by running any of the following commands:

cql-package --help
cql-package cql --help
cql-package elm --help

Example

cql-package elm --elm Elm\json --cql Cql\input --fhir c:\packager-output-fhir --cs c:\packager-output-cs

This command packages the ELM and CQL files from the specified directories and writes the generated FHIR Resources and C# code to the respective directories.

Further Reading

The CQL Packager tool is part of the Firely CQL SDK. More information can be found at Firely’s documentation site.