frappe-erpnext

To override core logic in a Frappe DocType, write a custom Python controller and link it via hooks to extend or override standard ERPNext methods. This ensures custom validations and server-side logic execute without modifying core framework files.

Adding custom validation logic to an ERPNext Sales Invoice involves writing a Python controller and mapping the validation event in hooks. This intercepts the save process to execute custom field checks before database commits.

Enqueueing background jobs in Frappe uses the `frappe.enqueue` method within your Python controllers. This offloads long-running tasks from the user request cycle to background workers, preventing UI timeouts.

The Frappe framework supports REST API interactions natively, allowing external applications to perform CRUD operations on DocTypes. This enables seamless data exchange and integration with external systems using standard HTTP requests.

The best way to handle database operations in ERPNext Python controllers is using the `frappe.db` object. This wrapper provides secure methods for querying and updating records while maintaining framework validation and caching layers.

Implementing client-side JavaScript for Frappe form interactions involves attaching custom scripts to DocTypes. This handles UI events like field value changes and form validations directly in the browser before data reaches the server.