Apex client-side to server-side constructor

Question

I am currently reading this Salesforce doc: https://developer.salesforce.com/docs/atlas.en-us.lightning.meta/lightning/controllers_server_apex_returning_data.htm

This is the code provided on the page teaching us that we need to annotate fields we want serialized to the client-side:

public class SimpleAccount {

@AuraEnabled public String Id { get; set; }
@AuraEnabled public String Name { get; set; }
public String Phone { get; set; }

// Trivial constructor, for server-side Apex -> client-side JavaScript
public SimpleAccount(String id, String name, String phone) {
    this.Id = id;
    this.Name = name;
    this.Phone = phone;
}

// Default, no-arg constructor, for client-side -> server-side
public SimpleAccount() {}

I am confused with the last comment near the no-arg constructor. What does it mean client-side to server-side? Why do we need this constructor?

Answer 1

This appears to be flawed. The Phone field is shown as a demonstration of data that will be present in the class, but not sent to the client (because of the missing @AuraEnabled). However, you don't need the zero-args constructor here. Constructors are not called during deserialization of a parameter, so you don't need it, even if you have another constructor defined. That said, it's also not harmful to have the constructor available, as it's basically 1-2 lines of code (depending on how you like to format your curly brackets).