Mastering Odoo Development: When to Extend and When to Relate

 

 Mastering Odoo Development: When to Extend and When to Relate

Overview: the golden rule of Odoo developer

As an Odoo developer, your work will often consist of customizing or adding features in an existing Odoo application. The most important rule to keep in mind is: Never modify Odoo core files directly.

Why? Making modifications to core files makes your application fragile and, most importantly, un-upgradeable.

Odoo provides powerful, built-in techniques called Inheritance that safely customize models (databases) and views (user interfaces). Mastering the three main types of inheritance is the key to writing clean, maintainable, and future-proof Odoo modules.

1 Classical Inheritance: The Extension Method

This is the most common and fundamental way to extend an existing Odoo data model, such as the `Customer` model, or `Sales Order` model. You are essentially telling Odoo, "I want to add new features to this existing structure."

 

How it Works & Usage

 Purpose: Extend an existing Odoo model by adding new fields, security checks, or business logic (methods) to it.

 Mechanism: You create a new Python object that tells Odoo to extend the original model definition. You do this by referencing the name of the original model in your extension file.

 

Method overriding: You may also override an existing function - say, one confirming a sales order. This is variably done by wrapping your custom logic around the original function. The best practice includes using a command called `super()` so that you can add validation before the original function runs, as well as follow-up actions after it runs, yet still execute the core Odoo logic.

Best Use Case

Adding a custom field (example - "Projected Ship Date" to a Sales Order).

Adding a validation rule that prevents a record from being saved unless specific conditions are met.

 

2.  Delegation Inheritance: The "Act-Like" Method

Delegation inheritance is used when you want your new, custom model to reuse all the data and behavior of an existing Odoo model. It creates a powerful, transparent relationship between two separate models.

How it Works & Usage

 Purpose: This allows a new model to act like another model without duplicating data. It forms a clean, one-to-one relationship.

 Mechanism: You define your new model (for instance, a `Vehicle`) and attach it to an existing model (for example, a `Contact` or `Partner`). By setting up delegation in this way, your `Vehicle` record automatically gets all of the `Contact` fields, such as name, address, and phone number, and they appear to belong to the `Vehicle` itself.

 Analogy: Consider an Employee record. An employee is a special kind of Odoo User. Delegation allows the Employee model to get and set the User's credentials and settings directly, again for ease of data entry and retrieval.

 

Best Use Case

Creating subtypes or specialized entities where the new object is essentially a version of an existing core object; for example, a Manufacturing Machine is a Fixed Asset.

UDP is a connectionless, best-effort protocol.

3 View Inheritance: The User Interface Customizer

This inheritance is used exclusively to modify Odoo's user interfaces' visual layout and structure (Forms, Lists, and Kanban boards). This is how you would go about changing the appearance without ever having to touch the underlying Python code.

How it Works & Usage 

Purpose: To add, remove, move, or hide elements like fields, buttons, and sections on an Odoo screen.

Mechanism: You define a new XML file that references the ID of the original view you want to change. In this file, you employ special positioning commands - such as "after," "before," or "replace" - joined with special selectors, called XPath, that precisely define where the element to be modified is located.

Safety: This is the safest way to change the UI because if the original view gets updated, your changes are isolated and easier to fix than if you had modified the original file.

Best Use Case Positioning your new custom field from Classical Inheritance in a specific location on a Form View.  Hiding a button that is unnecessary for your company's specific workflow. - The Developer's Takeaway Mastering Odoo inheritance will let you keep your custom code separate from the core. This strategy saves you from immense time and effort during upgrades of major versions, making your work stable, maintainable, and truly professional. Which Odoo core model have you found the most challenging to customize? Share your experience below!


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