Frappe Hooks

Use after_install to create initial data (roles, settings, default records).

Document event hooks

Run Python functions when any DocType triggers lifecycle events:

doc_events = {
    "Expense": {
        "validate": "myapp.overrides.expense.validate",
        "on_submit": "myapp.overrides.expense.on_submit",
    },
    "*": {  # all DocTypes
        "after_insert": "myapp.audit.log_creation",
    }
}

The function receives the document and event name:

def validate(doc, method):
    if doc.amount > 10000:
        frappe.throw("Amount exceeds limit")

Scheduled jobs

scheduler_events = {
    "daily": ["myapp.tasks.daily_cleanup"],
    "hourly": ["myapp.tasks.sync_data"],
    "cron": {
        "*/5 * * * *": ["myapp.tasks.check_status"]
    }
}

See background-jobs.md for details.

Desk includes (inject CSS/JS into desk)

app_include_css = "/assets/myapp/css/myapp.css"
app_include_js = "/assets/myapp/js/myapp.js"

Override standard classes

override_doctype_class = {
    "ToDo": "myapp.overrides.CustomToDo"
}

The override class MUST inherit from the original:

# myapp/overrides.py
from frappe.desk.doctype.todo.todo import ToDo

class CustomToDo(ToDo):
    def validate(self):
        super().validate()
        # custom logic

Use sparingly — prefer doc_events hooks when possible.

Whitelisted methods exposed via hooks

# Override standard whitelisted methods, use sparingly
override_whitelisted_methods = {
    "frappe.client.get_count": "myapp.api.custom_get_count"
}

Fixtures (export data with app)

fixtures = [
    "Custom Field",
    {"dt": "Role", "filters": [["name", "in", ["Expense Manager"]]]},
]

Export: bench --site <site> export-fixtures --app <app-name>

Website routes

website_route_rules = [
    {"from_route": "/expenses", "to_route": "expenses/index"},
    {"from_route": "/expenses/<path:name>", "to_route": "expenses/view"},
]

Common patterns

• Hook functions are dotted paths to importable Python functions
• Keep hook functions in dedicated files (e.g. overrides/, tasks.py)

Other useful hooks

# Add custom Jinja methods/filters available in templates
jinja = {
    "methods": ["myapp.utils.jinja.my_method"],
    "filters": ["myapp.utils.jinja.my_filter"],
}

# Add data to the boot response (loaded on Desk startup)
boot_session = "myapp.boot.boot_session"

# Permission query conditions for list filtering
permission_query_conditions = {
    "Expense": "myapp.permissions.expense_query_conditions",
}

# has_permission override
has_permission = {
    "Expense": "myapp.permissions.expense_has_permission",
}