Commands

To make any changes to the data, we issue commands. E.g:

val result = klerk.handle(
    Command(
        event = CreateAuthor,
        model = null,
        params = CreateAuthorParams(
            firstName = FirstName("Astrid"),
            lastName = LastName("Lindgren"),
        ),
    ),
    context,
    ProcessingOptions(CommandToken.simple()),
)

In the example above, we issue the command CreateAuthor with some parameters. Since we don´t want to execute this event on a specific model, we set mode = null.

When interacting with Klerk, we always provide a context. This includes information about who is the actor, i.e. on whose behalf is the command issued. This actor is among other things used when evaluating the authorization rules.

Options

A ProcessingOptions object must be supplied.

Idempotence

A command token is required. This token can ensures that the command is only executed if some preconditions are fulfilled. In the example above, a simple CommandToken is provided, this ensures idempotence (i.e. prevents the same command from occurring more than once).

A more advanced token can be used to make sure that the command is only accepted if some data is unchanged since the token was created.

Dry run

If a command is issued with CommandOption(dryRun = true), the command is evaluated, but it will have no effect. This can be used to see what would happen if the command would be issued for real. The response will contain the updated models as normal but will not be persisted. Also note that none of the actions or jobs will be executed.