Question

I’m new to object oriented programming and am slowly learning how to apply it to javascript. So please bear with me. 🙂

I have two basic objects:

1. “record” which contains methods for editing a single record from a recordset. (create, save, load, etc.)

2. “recordList” which contains methods for outputting a paginated list of record titles.

I would like for these objects to be able to work together. For example, if record.save() is called, recordList.refresh() is also called, so that the paginated list reflects the updated data.

To accomplish this, I have created a third object “control” which contains instances of both “record” and “recordList”. I am using “control” in the following fashion:

control = {}

    control.record = object.create("record");
    control.recordList = object.create("recordList");

    control.save = function() {

        this.record.save();
        this.recordList.refresh();

    };

This works. But I am wondering, is it proper? (I want to be sure I am not violating any of the rules of OO design in doing this.) Is there a better way?

Thanks in advance for your help.

Answer 1

Speaking from an OOP perspective, I don’t think a record would save itself. A record in a database is simply data, and the database itself is what does things with that data, whether it’s saving or loading or etc. That being said I’d make record be simply an object that holds data and would create a recordset object for interacting with the data. Within that recordset object you could put your recordList and update it accordingly. Something like:

var recordset = function() {
    var me = this;
    var currentRecord = object.create("record");
    var recordList = object.create("recordList");
    me.save = function() {
            //Insert record.save code here
            recordList.refresh();
    };
};

Something to note about that code. In that setup currentRecord and recordList can’t be accessed from outside the function and therefore you have encapsulation, one of the hallmarks of OOP. This is because the recordset function is a closure that “closes over” all variables within, meaning that every function within has access to the variables within the scope of recordset.

You could let the outside world get access through get or set functions:

    me.getRecordList = function() {
        return recordList.getArray(); //Not generally a good idea to simply return your internal object
    };