Mastering Frappe Framework – Part 4: Backend Development in Frappe

Why Backend Development in Frappe Matters

Frontend determines how your app looks.

Backend determines how your app works.

In Frappe, backend development means:

• Writing Python methods for business logic
• Using Frappe ORM to interact with the database
• Creating custom API endpoints
• Running scheduled tasks
• Sending notifications to users

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1. Writing Python Methods in DocTypes

Every DocType can have a Python controller file (created when you used –create-controller).

Example: Auto-set a status when due date passes.

import frappe
from frappe.model.document import Document
from datetime import date

class ToDoPlus(Document):
    def before_save(self):
        if self.due_date and self.due_date < date.today():
            self.status = "Overdue"

Key events you can use:

• before_insert(self) – Before a new record is saved
• validate(self) – Data validation before saving
• before_save(self) – Runs before save (update or insert)
• on_update(self) – Runs after saving
• on_trash(self) – Runs before delete

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2. Using Frappe ORM for Data Operations

Instead of writing SQL, you can use Frappe ORM.

Get all pending tasks:

tasks = frappe.get_all(
    "ToDo Plus",
    filters={"status": "Pending"},
    fields=["name", "title", "due_date"]
)

Get a single document:

doc = frappe.get_doc("ToDo Plus", "TASK-0001")

Create a new record:

doc = frappe.get_doc({
    "doctype": "ToDo Plus",
    "title": "Prepare Blog Draft",
    "status": "Pending"
})
doc.insert()

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3. Creating Custom API Endpoints

You can expose Python functions as REST APIs by whitelisting them.

In todo_plus/api.py:

import frappe

@frappe.whitelist()
def get_overdue_tasks():
    return frappe.get_all(
        "ToDo Plus",
        filters={"status": "Overdue"},
        fields=["name", "title", "due_date"]
    )

Access via API:

curl -X GET \
  "http://mysite.local/api/method/todo_plus.api.get_overdue_tasks" \
  -H "Authorization: token <api_key>:<api_secret>"

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4. Scheduling Background Jobs

Frappe’s scheduler can run tasks automatically at intervals.

In todo_plus/tasks.py:

import frappe
from datetime import date

def mark_overdue_tasks():
    frappe.db.set_value(
        "ToDo Plus",
        {"due_date": ("<", date.today()), "status": "Pending"},
        "status",
        "Overdue"
    )

In hooks.py:

scheduler_events = {
    "daily": [
        "todo_plus.tasks.mark_overdue_tasks"
    ]
}

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5. Sending Notifications

Use Frappe’s notification system to alert users.

Example:

frappe.sendmail(
    recipients=["user@example.com"],
    subject="Task Overdue",
    message="One of your tasks is overdue. Please check."
)

You can also create notifications directly from Desk → Notifications without coding.

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Key Learnings from Part 4

• How to write server-side logic with DocType controllers
• How to use Frappe ORM for database operations
• How to create custom API endpoints with @frappe.whitelist()
• How to schedule jobs with Frappe’s scheduler
• How to send email notifications programmatically

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What’s Next?

In Part 5, we’ll work on Frontend Development in Frappe:

• Custom pages with Jinja templates
• Client scripts for interactivity
• Modifying form layouts
• Using REST APIs in the frontend