so here is a situation that i have. I have a constructor function with many properties and methods. here are the properties:
var Brain = function(){
this.util = require('util');
this.fs = require('fs');
this.assert = require('assert');
this.Sequelize = require('sequelize');
this.JsonField = require('sequelize-json');
this.bcrypt = require('bcrypt-nodejs');
this.bodyParser = require('body-parser');
this.fileUpload = require('express-fileupload');
// Custom Modules
this.ModelsModule = require('./models');
this.TombModule = require('./tomb');
}
a few of the methods are defined to call a given callback and pass data to it, for example:
Brain.prototype.db_read = function(request, response, data, callback) {
var self = this;
self.ModelsModule[data.Model].findOne(data.where)
.then(function(obj) {
// console.log(obj);
callback(request, response, obj);
})
.catch(function(error){
console.log(error);
});
}
Here is the thing - the callback function is always going to be another method of the same constructor function. here is another method that would be a callback:
Brain.prototype.login = function(request, response, user) {
var self = this;
// console.log('form-data --- ', request.body);
if(user == null || user == undefined) {
console.log('Account Load: Failed');
return response.render( self.TombModule.pages['login'], {error: 'Invalid Credentials'} );
}
else {
// console.log(user.dataValues);
if( self.bcrypt.compareSync(request.body.pswrd, user.dataValues.pswrd) == false ) {
console.log('Account Load: Failed');
return response.render( self.TombModule.pages['login'], {error: 'Invalid Credentials'} );
}
console.log('Account Load: Successful');
request.session.you = {
id: user.dataValues.id,
f_name: user.dataValues.f_name,
m_initial: user.dataValues.m_initial,
l_name: user.dataValues.l_name,
icon: user.dataValues.icon,
background: user.dataValues.background,
email: user.dataValues.email,
phone: user.dataValues.phone,
fax: user.dataValues.fax,
uv: user.dataValues.uniqueValue
};
return response.redirect('/home');
}
}
In my app.js a new instance of Brain is created.
const RoutinesModule = require('./routines');
const brain = new RoutinesModule.Brain();
The Entire chain of events starts from an express POST route:
app.post('/login', function(request, response){
var data = {
Model: 'Users',
where: {where: {email: request.body.email}}
}
brain.db_read(request, response, data, brain.login);
});
Notice that the callback, the last parameter, for Brain.db_read is Brain.login, which is another method of the same constructor. here is where the problem is happening.
When POST requests to /login hits the app.js, it's going to query the database and give the results to any given function to handle it, in this case Brain.login
inside of Brain.db_read(), var self = this; works. it points to itself, the instance of the Brain. however, when it calls the callback which is Brain.login, the statement inside of Brain.login, var self = this; does not work. it results in undefined, causing an error.
Why is that happening? why is var self = this; inside of the Brain.login resulting in undefined?
Ultimately what i am trying to do is create a set of main functions to handle database operations(CRUD) instead of doing database operations inside of each individual function, which is/could be an indefinite amount.
I could easily just require that module in that function definition but i would strongly prefer to access its property for dynamic, scalable, and efficiency means.
Thanks!
