How Odoo's patch() Function Works Under the Hood

5.1 When Patches Are Applied

Patches are applied during Phase III of the Odoo frontend initialization lifecycle — after module-level code executes and registries are populated, but before the OWL component tree is mounted.

5.2 Execution Order Between Multiple Patches

When multiple modules patch the same method, the execution order is determined by the module dependency graph — not by alphabetical order or any other implicit rule.

• Declared dependency order is the only reliable guarantee. If Module B declares Module A in its __manifest__.py depends list, Module A's patch is applied first.
• For unrelated modules with no declared dependency, execution order is not guaranteed and depends on asset bundle composition.
• The last-applied patch is the outermost layer  it executes first when the method is called.
• super.method() resolves to the next layer inward via the JavaScript engine's native prototype lookup, ultimately reaching the original.

Example with two patches on the same component:

// Module A patch (applied first, inner layer):

patch(MyComp.prototype, {

    doWork() { console.log('A before'); super.doWork(); console.log('A after'); }

});



// Module B patch (applied second, outer layer):

patch(MyComp.prototype, {

    doWork() { console.log('B before'); super.doWork(); console.log('B after'); }

});



// Output when doWork() is called:

// B before → A before → [Original] → A after → B after

5.3 Execution Order Inside setup()

Code placed before super.setup() runs first (outermost patch wins). Code placed after super.setup() runs last (innermost / original runs first).

patch(MyComp.prototype, {

    setup() {

        // Runs BEFORE original setup

        this.earlyState = useState({ ready: false });

        super.setup();

        // Runs AFTER original setup

        onWillStart(() => this.loadData());

    }

});