Metadata "argument_to_config"

The argument_to_config metadata property maps an argument passed to the action to a configuration property with the given name.

Important, the argument must not be a function nor an object literal. Functions are already interpreted as handlers and object literals as action properties. When multiple arguments are provided, only the last one is extracted.

• Type: string

When writing and registering Nikita's actions, it is sometimes interesting to simplify how arguments are provided. Instead of passing an object literal with a configuration property inside it as a string, it is potentially more convenient to directly provide this property.

For example, the file.touch action accept a target configuration property. An example to use it is:

nikita.file.touch({target: 'some/file'})

Alternatively, thanks to the argument_to_config metadata, it is possible to simplify its execution with:

nikita.file.touch('some/file')

Note, when the same configuration property is provided to the action call, it doesn't overwrite it.

Usage

It is simplified using the argument_to_config metadata. The example below define two configuration properties key_1 and key_2 where:

nikita
// Register an action
.registry.register('my_action', {
  metadata: {
    argument_to_config: 'key_2'  },
  handler: ({config}) => {
    // key_2 is available in config
    console.info(config)
    // Handler implementation...
  }
})
// Passing `key_2` in the configuration object 
.my_action({key_1: 'value 1', key_2: 'value 2'})
// Is similar to passing `key_2` as a string argument
.my_action({key_1: 'value 1'}, 'value 2')
// Both calls print:
// { key_1: 'value 1', key_2: 'value 2' }

Manual alternative

The manual implementation of this functionality implies adding to the action handler a few lines of code:

nikita
// Register an action
.registry.register('my_action', ({metadata, config}) => {
  // Map argument to config
  if (metadata.argument != null)    if (config.my_key == null) // Don't overwrite config      config.my_key = metadata.argument  // Now, my_key is available in config
  console.info(config.my_key)
  // Handler implementation...
})