I'm beginner in em ES6, and I need instantiate new objects inside a class. How the best way to make this, and how I can access "in this case" the connection in the function getName().
Probably talking nonsense, but I need to understand how this works to evolve. Anyone would have any tips for me.
above little exemple
class Test {
constructor(array){
this.array = array
// CONNECT DATABASE
var connection = mysql.createConnection({this.array})
}
getName(){
query = 'SELECT * FROM mytable LIMIT 1'
connection.query(query, function (err, rows, fields) {
return rows
})
}
}
array = {
host: 'localhost',
user: 'root',
password: '',
database: 'mydb'
}
let T = new Test(array)
T.getName()
// error connection is not defined
In this example, var connection is a variable that's only in the context of the constructor.
You need to use this.connection to have it actually be a member of the object itself. Change it to this.connection in all places you use it. You don't need a var, let or const when defining a variable like this.
class Test {
constructor(array){
this.array = array
// CONNECT DATABASE
this.connection = mysql.createConnection({this.array})
}
getName(){
query = 'SELECT * FROM mytable LIMIT 1'
this.connection.query(query, function (err, rows, fields) {
return rows
})
}
}