Creating Multi-Step Wizard Forms in Odoo: Complete Tutorial

from odoo import models, fields, api

class MassOrderUpdate(models.TransientModel):
    _name = 'sale.mass.update.wizard'
    _description = 'Mass Update Sale Orders'
    
    # State determines which "page" of the wizard to show
    state = fields.Selection([
        ('selection', 'Selection'),
        ('review', 'Review'),
    ], default='selection')
    
    # STEP 1 FIELDS
    target_order_ids = fields.Many2many('sale.order', string='Orders to Update')
    new_priority = fields.Selection([
        ('0', 'Normal'),
        ('1', 'Urgent')
    ], string='New Priority')
    new_shipping_id = fields.Many2one('delivery.carrier', string='New Shipping Method')
    
    # STEP 2 FIELDS
    note = fields.Text(string='Log Note', help='Note to add to chatter')
    
    @api.model
    def default_get(self, fields):
        """Pre-populate the wizard with selected orders from the list view."""
        res = super(MassOrderUpdate, self).default_get(fields)
        
        # Context contains 'active_ids' when triggered from a list view
        active_ids = self.env.context.get('active_ids', [])
        
        if active_ids:
            res['target_order_ids'] = [(6, 0, active_ids)]
        
        return res
    
    def action_next(self):
        """Move to the next step (Review)."""
        self.state = 'review'
        
        # Return a window action to "refresh" the wizard view with new fields
        return {
            'type': 'ir.actions.act_window',
            'res_model': self._name,
            'res_id': self.id,
            'view_mode': 'form',
            'target': 'new',
        }
    
    def action_back(self):
        """Move back to the previous step."""
        self.state = 'selection'
        
        return {
            'type': 'ir.actions.act_window',
            'res_model': self._name,
            'res_id': self.id,
            'view_mode': 'form',
            'target': 'new',
        }
    
    def action_apply(self):
        """Final Step: Apply changes to the real models."""
        for order in self.target_order_ids:
            # Apply changes
            update_vals = {}
            
            if self.new_priority:
                update_vals['priority'] = self.new_priority
            
            if self.new_shipping_id:
                update_vals['carrier_id'] = self.new_shipping_id.id
            
            order.write(update_vals)
            
            # Log the change
            if self.note:
                order.message_post(body=self.note)
        
        # Close the wizard
        return {'type': 'ir.actions.act_window_close'}

<odoo>
    <record id="view_mass_order_update_form" model="ir.ui.view">
        <field name="name">sale.mass.update.wizard.form</field>
        <field name="model">sale.mass.update.wizard</field>
        <field name="arch" type="xml">
            <form string="Mass Order Update">
                <!-- Header / Progress Bar -->
                <field name="state" invisible="1"/>
                
                <sheet>
                    <!-- STEP 1: SELECTION -->
                    <!-- Only visible when state is 'selection' -->
                    <group states="selection" string="Update Options">
                        <field name="target_order_ids" widget="many2many_tags" readonly="1"/>
                        <field name="new_priority" widget="priority"/>
                        <field name="new_shipping_id"/>
                    </group>
                    
                    <!-- STEP 2: REVIEW -->
                    <!-- Only visible when state is 'review' -->
                    <group states="review" string="Review & Log">
                        <div class="alert alert-info">
                            You are about to update <field name="target_order_ids" widget="statinfo"/> orders.
                            This action cannot be undone.
                        </div>
                        <field name="note" placeholder="Reason for update..."/>
                    </group>
                </sheet>
                
                <footer>
                    <!-- Buttons for Step 1 -->
                    <button string="Next" name="action_next" type="object"
                            class="btn-primary" states="selection"/>
                    
                    <!-- Buttons for Step 2 -->
                    <button string="Back" name="action_back" type="object"
                            class="btn-secondary" states="review"/>
                    <button string="Confirm Update" name="action_apply" type="object"
                            class="btn-primary" states="review"/>
                    
                    <!-- Cancel Button (Always visible) -->
                    <button string="Cancel" special="cancel"/>
                </footer>
            </form>
        </field>
    </record>
    
    <!-- Action to open wizard -->
    <record id="action_mass_order_update" model="ir.actions.act_window">
        <field name="name">Mass Update Orders</field>
        <field name="res_model">sale.mass.update.wizard</field>
        <field name="view_mode">form</field>
        <field name="target">new</field>
        <field name="binding_model_id" ref="sale.model_sale_order"/>
        <field name="binding_view_types">list</field>
    </record>
</odoo>

# Inside the wizard model
@api.onchange('new_shipping_id')
def _onchange_carrier(self):
    """Filter service levels based on selected carrier."""
    if self.new_shipping_id:
        return {
            'domain': {
                'service_level_id': [('carrier_id', '=', self.new_shipping_id.id)]
            }
        }