Call and user-defined handlers

Nikita gives you the choice between calling your own function, which we call handlers, or calling an registered function by its name.

Calling a function

In its simplest form, user defined handler is just a function passed to "call". Here's an illustration:

nikita
.call(() => {
  // Print 'Hello world!' message
  console.info('Hello world!')
})

This is internally converted to:

nikita
.call({
  $handler: () => {
    // Print 'Hello world!' message
    console.info('Hello world!')
  }
})

Use the expanded object syntax to pass additional information. For example, we could add the retry metadata or configuration properties:

nikita
.call({
  $retry: 2,  my_config: 'my_value',
  $handler: ({config}) => {
    // Print the config value
    console.info(config.my_config)
  }
})

Note, the above code could be arguably simplified using 2 arguments:

nikita
.call({
  $retry: 2,
  my_config: 'my_value',
}, ({config}) => {
  // Passing config.my_config
})

Calling a module

If no handler is yet defined, a string is interpreted as an external module exporting a handler function or object. The 4 calls below are all equivalent:

nikita
// Pass with require
.call(require('path/to/module'))
// Pass with require in expanded object syntax
.call({
  $handler: require('path/to/module')
})
// Pass as a string
.call('path/to/module')
// Pass as a string in expanded object syntax
.call({
  $handler: 'path/to/module'
})

Internally, the module is required with the call require.main.require.

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