DAML codegen

Introduction

You can use the DAML codegen to generate Java and Scala classes representing DAML contract templates. These classes incorporate all boilerplate code for constructing corresponding ledger CreateCommand and ExerciseCommand.

Running the DAML codegen

The basic command to run the DAML codegen is:

$ daml codegen [java|scala] [options]

There are two modes:

• command line configuration, specifying all settings in the command line
• project file configuration, specifying all settings in the daml.yaml

Command line configuration

Help for DAML to Java codegen:

$ daml codegen java --help

Help for DAML to Scala codegen:

$ daml codegen scala --help

Both DAML to Java and DAML to Scala take the same set of configuration settings:

Usage: codegen [options] <DAR-file[=package-prefix]>...

Code generator for the DAML ledger bindings.

  <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

Project file configuration

The above settings can be configured in the codegen element of the DAML project file daml.yaml. Here is an example:

sdk-version: 0.0.0
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 run the above configuration to generate Java code:

$ daml codegen java

and to generate Scala code:

$ daml codegen scala

The equivalent DAML to Java command line configuration:

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

and DAML to Scala command line configuration:

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

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

"com.daml" %% "bindings-scala" % 1.0.1

and for Java, add the following Maven dependency:

<dependency>
  <groupId>com.daml</groupId>
  <artifactId>bindings-java</artifactId>
  <version>1.0.1</version>
</dependency>