Specify arguments in grails command - grails

Question

I'm using grails 3.2.6. I'm writing a custom grails command. It's a command and not a script because I need access to object in the spring application context in the command. I would like for my command to accept command line arguments with values such as "name" and "group" and "id". For example, I'd like to be able to run the command like this:
grails run-command process-group --name=foo --group=bar --id=2
However, when I do this, my command implementation class doesn't seem to have access to any of these arguments (name, group, or id). I've tried accessing them through the args attribute that comes from the GrailsApplicationCommand trait, but that is empty. I've also tried accessing it through various methods of the CommandLine object that is accessible through executionContext.commandLine object which also comes from the GrailsApplicationCommand trait. However, everything there seems to be empty as well (undeclaredOptions is empty, remainingArgs is empty, rawArguments just has my command name which is "process-group", etc.). If I remove the leading "--" from my argument names like this:
grails run-command process-group name=foo group=bar id=2
then the args attribute contains 3 entries: ["name=foo", "group=bar", and "id=2"]. I suppose that I could implement my command this way (no leading "--" on the command arguments), but it's kind of ugly, and it also means that I have to parse the arguments myself. The grails docs (http://docs.grails.org/latest/guide/single.html#creatingCustomCommands) say that, "Since Grails 3.2.0, commands have similar abilities as scripts in regards to retrieving arguments, template generation, file access, and model building." I'm interested in the retrieving arguments part of that statement. The examples shown in the documentation for scripts (not commands) show (http://docs.grails.org/latest/guide/single.html#creatingCustomScripts) how to declare parameters that a script will take from the command line. For example, this command line is supposed to work with a custom script that declares the "force" parameter for the generate-all custom script:
grails generate-all MyClass --force
This all seems to be tied to the use of the description() method in the script:
description( "Generates a controller that performs CRUD operations and the associated views" ) {
usage "grails generate-all <<DOMAIN CLASS>>"
flag name:'force', description:"Whether to overwrite existing files"
argument name:'Domain Class', description:'The name of the domain class'
}
However, there doesn't seem to be a description() method available for use for custom commands as there is for custom scripts. I just confused about how the grails docs state that retrieving arguments is supposed to now work the same for both custom scripts and custom commands, yet I can't seem to retrieve arguments from a custom command like I can from a custom script. Is there a way that I can retrieve the arguments for a custom command just like it can be done for a custom script?

Answer 1

Set the properties using the -D option:
-Dsample.message=foo
Grab the system properties using the follow code:
System.properties['sample.message']
Link to the where I found this example:
Passing Properties