Frappe State Machine Helper

Frappe State Machine Helper

Generate state machine logic for managing complex document states and transitions in Frappe DocTypes.

When to Use This Skill

Claude should invoke this skill when:

• User wants to implement document status management
• User needs state transition logic
• User mentions state machine, status workflow, or document lifecycle
• User wants to validate state transitions
• User needs state-dependent behavior

Capabilities

1. State Transition Logic

Order Status State Machine:

class SalesOrder(Document):
    def validate(self):
        self.validate_state_transition()

    def validate_state_transition(self):
        """Validate allowed state transitions"""
        if not self.is_new():
            old_status = frappe.db.get_value('Sales Order', self.name, 'status')

            # Define allowed transitions
            allowed_transitions = {
                'Draft': ['Pending', 'Cancelled'],
                'Pending': ['Confirmed', 'Cancelled'],
                'Confirmed': ['In Progress', 'Cancelled'],
                'In Progress': ['Completed', 'On Hold'],
                'On Hold': ['In Progress', 'Cancelled'],
                'Completed': [],  # Terminal state
                'Cancelled': []   # Terminal state
            }

            if old_status != self.status:
                allowed = allowed_transitions.get(old_status, [])
                if self.status not in allowed:
                    frappe.throw(
                        _(f'Cannot transition from {old_status} to {self.status}')
                    )

    def on_submit(self):
        self.status = 'Confirmed'

    def on_cancel(self):
        self.status = 'Cancelled'

2. State-Dependent Actions

Actions Based on State:

class PaymentEntry(Document):
    def validate(self):
        if self.status == 'Draft':
            self.validate_draft_entry()
        elif self.status == 'Submitted':
            self.validate_submitted_entry()

    def before_submit(self):
        # Actions before state change
        if self.payment_type == 'Pay':
            self.validate_sufficient_balance()

        self.status = 'Submitted'

    def on_cancel(self):
        # Reverse actions
        if self.status == 'Submitted':
            self.reverse_gl_entries()

        self.status = 'Cancelled'

References

State Management Examples:

• Sales Invoice: https://github.com/frappe/erpnext/blob/develop/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
• Purchase Order: https://github.com/frappe/erpnext/blob/develop/erpnext/buying/doctype/purchase_order/purchase_order.py

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