I try to write a copy function to copy data from table to same table.

hre_formmst_id is Many2one field. hre_formdtl_ids is One2many field.

Use a button to call this function.

def formmst_copy_func(self):
        _logger.info('=== formmst_copy_func start ===')
        for record in self:
            formbas_obj = self.env['hre.formmst']
            defaults = {
                'form_no': record.form_no,
                'hre_orgbas_id': record.hre_orgbas_id.id if record.hre_orgbas_id else False,
                'form_name': record.hre_formmst_id.form_name,
                'form_type': record.hre_formmst_id.form_type,
                'calculate_type': record.hre_formmst_id.calculate_type,
                'total_score': record.hre_formmst_id.total_score,
                'hre_formdtl_ids': record.hre_formmst_id.hre_formdtl_ids,
            }
            formbas_obj.create(defaults)
        _logger.info('=== formmst_copy_func end ===')

<record id="form_hre_formbas_copy_wizard" model="ir.ui.view">
    <field name="name"<form.hre.formbas.copy.wizard</field>
    <field name="model"<hre.formbas.copy.wizard</field>
    <field name="arch" type="xml">
        <form>
            <group col="4">
                <field name="hre_formmst_id"/>
                <newline/>
                <field name="form_no"/>
                <field name="hre_orgbas_id"/>
            </group>
            <footer>
                <button string="Copy" name="formmst_copy_func" type="object" class="oe_highlight"/>
                or
                <button string="Cancel" special="cancel" type="object" class="oe_link"/>
            </footer>
        </form>
    </field>
</record>

The function can copy data successfully.
But the hre_formdtl_ids in the original data disappeared.
How can I fix the function? Please give me some suggestions. Thanks!