Generate Document Hooks

Create document lifecycle hooks using frappe-microservice-lib hook system.

When to Use

• Need code on document lifecycle events
• Want to avoid modifying Frappe core
• Prefer function-based hooks over controllers
• Need global hooks for all doctypes

Core Patterns

1. Hook Registration

# Global hook - runs for ALL doctypes
@app.tenant_db.on('*', 'before_insert')
def ensure_tenant_id(doc):
    from flask import g
    if not doc.tenant_id and hasattr(g, 'tenant_id'):
        doc.tenant_id = g.tenant_id

# DocType-specific hook
@app.tenant_db.on('Sales Order', 'before_insert')
def set_order_defaults(doc):
    if not doc.status:
        doc.status = 'Draft'
    if not doc.transaction_date:
        doc.transaction_date = frappe.utils.today()

@app.tenant_db.on('Sales Order', 'validate')
def validate_order(doc):
    if not doc.customer:
        frappe.throw("Customer is required")
    if doc.grand_total and doc.grand_total < 0:
        frappe.throw("Order total cannot be negative")

2. Available Events

• before_validate, validate, before_insert, after_insert
• before_update, after_update, before_save, after_save
• before_delete, after_delete

3. Multiple Hooks

# All hooks run in registration order
@app.tenant_db.on('Sales Order', 'before_insert')
def set_defaults(doc):
    if not doc.status:
        doc.status = 'Draft'

@app.tenant_db.on('Sales Order', 'before_insert')
def calculate_totals(doc):
    # Runs after set_defaults
    doc.calculate_totals()

4. Error Handling

@app.tenant_db.on('Sales Order', 'validate')
def validate_order(doc):
    try:
        if not doc.customer:
            frappe.throw("Customer is required")
    except frappe.ValidationError:
        raise
    except Exception as e:
        frappe.log_error(f"Validation error: {e}")

Key Patterns

1. Global hooks first: Use '*' for hooks applying to all doctypes
2. DocType-specific after: Register specific hooks after global ones
3. Validation in validate: Use validate hook for business rules
4. Defaults in before_insert: Set defaults before document is saved
5. Notifications in after_insert: Send notifications after successful creation
6. Error handling: Use frappe.throw() for validation errors

Remember: This skill is model-invoked. Claude will use it autonomously when detecting hook development needs.