Hello! Here is an example for the case your stage field is a Selection with this values [('draft','Draft'), ('confirm','Confirmed'), ('approved','Approved'),('rejected','Rejected')]:

@api.multi
def write(self, values):
    if 'state' in values:
        previous_state = self.state
        new_state = values.get('state')
        if (new_state in ['approved','rejected']) and (not self.env.user.has_group('your_module.your_group_xml_id')):
            raise ValidationError(_("Only Managers can perform that move !"))
        #elif some other_conditions:
            #some other logics
    return super(YOUR CLASS, self).write(values)

It's also possible with Automated Actions, as explained here (this is a more complex example with validation, but it could be simplified):

This example has a “Financial Viability” check and a “Legal Approval” check that are mandatory before the Lead / Opportunity can be moved to one of the later stages.

Start by creating an Automated Action:

Python Code

# Require Financial Viability
if record.stage_id.name in ['Qualified', 'Proposition', 'Won'] and not record.x_studio_financial_viability:
    raise Warning('Please check Financial Viability for this Opportunity!')

# Require Legal Approval
if record.stage_id.name in ['Proposition', 'Won'] and not record.x_studio_legal_approval:
    raise Warning('Please check Legal Approval for this Opportunity!')

Odoo 14

Note that the syntax is slightly different in Odoo 14

raise UserError('Please check Legal Approval for this Opportunity!')

Results

Set the “Financial Viability” as checked, and stage can be changed:

Validation is done when the stage is changed in the Kanban view (as above).

It’s also done in the Form View:

The check will be done everywhere and cannot be overridden. 

Hi,

You can check that in the write function of the model. and raise an error.

for eg:

@api.multi
def write(self, values):
    if (YOUR CONDITION):
            raise ValidationError(_("You can't perform that move !"))
    return super(YOUR CLASS, self).write(values)

Thank you.

What about:

<field name="stage" attrs="{'readonly': [('group_ids','in',[g.id for g in user.groups_id])]}"/> 

you can stop that by modifying the attribute of stage_id for example

<field name="stage_id" position="attributes">
    <attribute name="readonly">True</attribute>
</field>