Guide Writing Hooks - osama1998H/Moca GitHub Wiki

Writing Hooks

Register hooks in Initialize(cr, hr), priority ordering, dependency declarations, and document event constants.

Overview

Hooks let apps react to document events and register controller-aware behaviour during app initialization. In current Moca builds, hooks are registered from an app's Initialize(cr, hr) function, which is exposed through apps.MustRegisterInit(...) in hooks.go.

Document Event Hooks

package myapp

import (
    "github.com/osama1998H/moca/pkg/apps"
    "github.com/osama1998H/moca/pkg/document"
    "github.com/osama1998H/moca/pkg/hooks"
)

func init() {
    apps.MustRegisterInit("myapp", Initialize)
}

func Initialize(cr *document.ControllerRegistry, hr *hooks.HookRegistry) {
    _ = cr

    hr.Register("Sales Order", document.EventBeforeSave, hooks.PrioritizedHandler{
        AppName:  "myapp",
        Handler:  calculateTotal,
        Priority: 10,
    })

    hr.Register("Sales Order", document.EventAfterInsert, hooks.PrioritizedHandler{
        AppName:  "myapp",
        Handler:  sendNotification,
        Priority: 20,
    })
}

func calculateTotal(ctx *document.DocContext, doc document.Document) error {
    // Business logic here
    return nil
}

func sendNotification(ctx *document.DocContext, doc document.Document) error {
    return nil
}

Available Events

Use the document.Event... constants when registering handlers:

document.EventBeforeInsert
document.EventAfterInsert
document.EventBeforeValidate
document.EventValidate
document.EventBeforeSave
document.EventAfterSave
document.EventOnUpdate
document.EventBeforeSubmit
document.EventOnSubmit
document.EventBeforeCancel
document.EventOnCancel
document.EventOnTrash
document.EventAfterDelete
document.EventOnChange

Rename hooks are handled by document controllers rather than HookRegistry because they carry the old and new names.

Priority & Dependencies

Priority: Lower number runs first (10 before 20)
Dependencies: DependsOn lists app names that must run before yours

hr.Register("Sales Order", document.EventBeforeSave, hooks.PrioritizedHandler{
    AppName:   "pricing",
    Handler:   applyDiscount,
    Priority:  20,
    DependsOn: []string{"taxes"}, // Run after handlers registered by the taxes app
})