Action

Action is another type of Interceptor. Unlike Filter, Action can accept multiple parameters and it only returns either an empty Promise.resolve() or a Promise.reject(ex) with an error.

Creating Action

Similar to Filter, you can create action by either declaring an Action class or calling actionManager.create().

Declaring Action Class

Action class must expose a function named do . This function will be invoked whenever the action gets performed.

Following example demonstrates a LoggingAction that writes log to console when price calculation completed:

class LoggingAction {

    async do(original, discount, tax) {
        console.log(`Calculation completed. Original: ${original}, Discount: ${discount}, Tax: ${tax}`);
    }
}

or:

function LoggingAction() {

    this.do = function(original, discount, tax) {
        console.log(`Calculation completed. Original: ${original}, Discount: ${discount}, Tax: ${tax}`);
        return Promise.resolve();    
    }
}

Creating Action via Action Manager

A better way to create action is to use Action Manager. Its usage is similar to Filter Manager:

var action = actionManager.create(async (original, discount, tax) => {
    console.log(`Calculation completed. Original: ${original}, Discount: ${discount}, Tax: ${tax}`);
});

or:

var action = actionManager.create((original, discount, tax) => {
    console.log(`Calculation completed. Original: ${original}, Discount: ${discount}, Tax: ${tax}`);
    return Promise.resolve();
});

Creating Action Manager

Action Manager centralize action registration and provides a method to invoke actions. To create a new Action Manager:

const { action } = require('robo-toolkit');
// or
const _a = require('robo-toolkit').action;

const actionManager= _a.createManager();

Note that _a is already a static global instance of Action Manager.

Registering Action

To register an action to Action Manager:

actionManager.add(name, action, priority);

In which:

• name is name of the action. Multiple actions with the same name will be chained.

• action is the action created using methods mentioned in previous section.

• priority is a number indicating priority of the action in the chain. The lower number, the higher priority. The higher prioritized action will be invoked prior to the lower ones. Default is zero.

Let's register our LoggingAction to the global Action Manager:

_a.add('after-calculate-price', new LoggingAction());

or:

_a.add('after-calculate-price', _a.create(async (original, discount, tax) => {
    console.log(`Calculation completed. Original: \$${original}, Discount: ${discount}%, Tax: ${tax}%`);
}));

Invoking Action

To invoke a specified action, call do on Action Manager:

await actionManager.do(name, ...args);

Following example invokes the after-calculate-price action:

await _a.do('after-calculate-price', 100, 10, 5);

Output console will look like:

Calculation completed. Original: $100, Discount: 10%, Tax: 5%