I used the attendance validation  in my custom class.I used @api.constrain that triggers following method when there is change to 's2' field

@api.constrains('s2')def constraint_action(self,cr, uid, ids, context=None):

for att in self.browse(cr, uid, ids, context=context):

# search and browse for first previous and first next records

prev_att_ids = self.search(cr, uid, [('EID', '=', att.EID), ('date', '<', att.date),

('action', 'in', ('sign_in', 'sign_out'))], limit=1, order='date DESC')

next_add_ids = self.search(cr, uid, [('EID', '=', att.EID), ('date', '>', att.date),

('action', 'in', ('sign_in', 'sign_out'))], limit=1, order='date ASC')

prev_atts = self.browse(cr, uid, prev_att_ids, context=context)

next_atts = self.browse(cr, uid, next_add_ids, context=context)

# check for alternance, return False if at least one condition is not satisfied

if prev_atts and prev_atts[0].action == att.action: # previous exists and is same action 

self._columns('state' '=' 'True')-----------------------------> This doesn't work

return True

I declared following variables at starting

class attendance(models.Model):

_name = "attendance.analysis"

_description = "attendance analysis"

_state = fields.boolean("state?",default = False)

_columns = { 'EID': fields.integer('Employee ID', required=True),

'action': fields.selection([('sign_in', 'Sign In'), ('sign_out', 'Sign Out')], 'Employee Action'),

'date': fields.datetime('Employee Date', required=True, select=1),

's1':fields.char("s1"),

's2':fields.char("s2", required=True),

's3':fields.char("s3"),

's4':fields.char("s4"),

'state':fields.boolean("state?",default = False)

}

I want to access the state field in columns. How can I access it 

I want to change this boolean so that tree color can be changed on the view.xml.

Thanks in advance