Sails-beforeBlueprint-Policy

beforeBlueprint.js

/**
 * beforeBlueprint
 *
 * @module      :: Policy
 * @description :: Simple policy to enable hooks into the model which can act upon req, res objects.
 * @docs        :: http://sailsjs.org/#!documentation/policies
 *
 */

var actionUtil = require( 'sails/lib/hooks/blueprints/actionUtil' );

capitaliseFirstLetter = function ( string ) {
  return string.charAt( 0 ).toUpperCase() + string.slice( 1 );
};

module.exports = function ( req, res, next ) {

  var Model = actionUtil.parseModel( req );
  var blueprint = capitaliseFirstLetter( req.options.action ); // we actually enable this for all actions, not only blueprints

  if ( typeof Model[ "controlBefore" + blueprint ] === "function" ) {
    var result = Model[ "controlBefore" + blueprint ]( req, res, next );
    //next();
  } else {
    sails.log.debug( 'Policy beforeBlueprint: Model "' + Model.identity + '" has no method controlBefore' + blueprint + '.' );
    next();
  }

};

user.js

// Model defintion api/models/user.js

module.exports = {

  attributes: {
    name: "string",
    "posts": {
      collection: "post",
      via: "user"
    }
  },

  // beforeFind hook to modify the request before it hits the find blueprint
  // other hooks possible, with the naming schema of controlBefore*Blueprint
  controlBeforeFind: function ( req, res, next ) {
    // modify req.options.where OR req.body OR req.query as you need
    next();
  }
};

This Policy enables hooks into the Model to provide function that can modify request and response options prior to a Blueprint being executed. Very useful for access control or setting up default associations between models.

Oh man, this is awesome. I've been trying to figure out how to check unique username before user creation, and this looks like the perfect solution.

@IanVS
This is a workaround to implement custom lifecycle callback. To check unique username before user creation you can use the default lifecycle callback beforeCreate in your model like:

beforeCreate: function(values, cb) {
   ...
 },

Please refer docs for details.