DAML codegen

Introduction

You can use the DAML codegen to generate Java, Scala, and JavaScript/TypeScript classes representing DAML contract templates. These classes incorporate all boilerplate code for constructing corresponding ledger com.daml.ledger.api.v1.CreateCommand, com.daml.ledger.api.v1.ExerciseCommand, com.daml.ledger.api.v1.ExerciseByKeyCommand, and com.daml.ledger.api.v1.CreateAndExerciseCommand.

Running the DAML codegen

The basic command to run the DAML codegen is:

$ daml codegen [java|scala|js] [options]

There are two modes:

• Command line configuration, specifying all settings in the command line (all codegens supported)
• Project file configuration, specifying all settings in the daml.yaml (currently Java and Scala only)

Command line configuration

Help for each specific codegen:

$ daml codegen [java|scala|js] --help

Java and Scala codegens take the same set of configuration settings:

<DAR-file[=package-prefix]>...
                         DAR file to use as input of the codegen with an optional, but recommend, package prefix for the generated sources.
-o, --output-directory <value>
                         Output directory for the generated sources
-d, --decoderClass <value>
                         Fully Qualified Class Name of the optional Decoder utility
-V, --verbosity <value>  Verbosity between 0 (only show errors) and 4 (show all messages) -- defaults to 0
-r, --root <value>       Regular expression for fully-qualified names of templates to generate -- defaults to .*
--help                   This help text

JavaScript/TypeScript codegen takes a different set of configuration settings:

DAR-FILES                DAR files to generate TypeScript bindings for
-o DIR                   Output directory for the generated packages
-s SCOPE                 The NPM scope name for the generated packages;
                        defaults to daml.js
-h,--help                Show this help text

Project file configuration (Java and Scala)

For Java and Scala the above settings can be configured in the codegen element of the DAML project file daml.yaml. At present the JavaScript/TypeScript codegen does not support this. See this issue for status on this feature.

Here is an example:

sdk-version: 1.2.0
name: quickstart
source: daml
scenario: Main:setup
parties:
  - Alice
  - Bob
  - USD_Bank
  - EUR_Bank
version: 0.0.1
exposed-modules:
  - Main
dependencies:
  - daml-prim
  - daml-stdlib
codegen:
  java:
    package-prefix: com.daml.quickstart.iou
    output-directory: java-codegen/src/main/java
    verbosity: 2
  scala:
    package-prefix: com.daml.quickstart.iou
    output-directory: scala-codegen/src/main/scala
    verbosity: 2

You can then run the above configuration to generate your Java or Scala code:

$ daml codegen [java|scala]

The equivalent Java or Scala command line configuration would be:

$ daml codegen [java|scala| ./.daml/dist/quickstart-0.0.1.dar=com.daml.quickstart.iou --output-directory=java-codegen/src/main/java --verbosity=2

In order to compile the resulting Java or Scala classes, you need to add the corresponding dependencies to your build tools.

For Scala, you can depend on:

"com.daml" %% "bindings-scala" % YOUR_SDK_VERSION

For Java, add the following Maven dependency:

<dependency>
  <groupId>com.daml</groupId>
  <artifactId>bindings-java</artifactId>
  <version>YOUR_SDK_VERSION</version>
</dependency>

Note

Replace YOUR_SDK_VERSION with the version of your DAML SDK