How to Add Subcomponents to Main Components in OWL

Introduction:

Odoo, the powerful open-source business application platform, offers developers the ability to create modular and reusable components to build intricate user interfaces. A fundamental feature of Odoo is the capability to incorporate subcomponents into main components. This empowers developers to break down their application's functionality into manageable parts, resulting in easier code maintenance and extensibility. In this comprehensive blog post, we will delve into the process of adding subcomponents to the main components in Odoo, illustrating the concept through a practical example.

Understanding Subcomponents:

Let's begin by examining the code structure of a subcomponent in Odoo. In our example, we will explore a subcomponent called `NoteComponent` that represents a note-taking feature. To define the subcomponent, we start by creating a template. The template specifies the component name, where "subcomponent" refers to the module name, and "NoteComponent" denotes the name of the component itself. Within the template, we establish the body of the subcomponent, which, in our case, is a text area for taking notes. This subcomponent will subsequently be added to the main component.

XML:
```
<?xml version="1.0" encoding="UTF-8"?>
<templates id="template" xml:space="preserve">
    <t t-name="subcomponent.NoteComponent" owl="1">
       <textarea placeholder="Enter Something..." class="notes_text"></textarea>
    </t>
</templates>
```

JavaScript:
```
/** @odoo-module */
const { Component } = owl;
export class NoteComponent extends Component {
   function_name(){
        // Enter your functionality...
   }
}
NoteComponent.template = 'subcomponent.NoteComponent';
```

JavaScript:
```
/** @odoo-module **/
import { NoteComponent } from "./notecomponent";
import { registry } from "@web/core/registry";
import { Component } from "@odoo/owl";
export class Noteitem extends Component {
   _toggle_note() {
       $(this.__owl__.bdom.el.querySelectorAll('.notes_text')).toggle();
   }
}
Noteitem.template = "subcomponent.Noteitem";
Noteitem.components = { NoteComponent };
export const systrayItem = {
   Component: Noteitem,
};
registry.category("systray").add("Noteitem", systrayItem, { sequence: 1 });
```

XML:
```
<?xml version="1.0" encoding="UTF-8"?>
<templates id="template
" xml:space="preserve">
    <t t-name="subcomponent.NoteItem" owl="1">
        <div>
            <div class="note_item_icon" t-on-click="_toggleNote">
                <span><i class="fa fa-file-text"></i></span>
            </div>
            <NoteComponent position="'bottom-end'"/>
        </div>
    </t>
</templates>
```