In OpenERP while saving data I got this error : ProgrammingError: can't adapt type 'dict' 

I am having two tables : 

class hr_employee(osv.osv):
    _inherit = 'hr.employee'
    _name = 'hr.employee'
    _columns = {
                'emp_code':fields.char('Employee Code', size=6, readonly=True),
                'religion_id':fields.many2one('hr.religion', 'Religion'),
                'pan_id':fields.char('PAN Number', size=10),
                'marriage_date':fields.date('Marriage Date'),
                'lang_speak_ids':fields.many2many('hr.language','rel_empspeak_lang', 'employee_id','language_id', 'Languages Speak'),
                'lang_write_ids':fields.many2many('hr.language','rel_empwrite_lang', 'employee_id','language_id', 'Languages Write'),
                'education_ids':fields.one2many('hr.education.detail','employee_id', 'Courses'),
                'family_detail_ids':fields.one2many('hr.family.detail','employee_id', 'Family Details'),
                'employement_detail_ids':fields.one2many('hr.employment.detail','employee_id', 'Work Experience Information'),
                'reference_detail_ids':fields.one2many('hr.reference.detail','employee_id', 'Reference Details'),
                'training_detail_ids':fields.one2many('hr.training.detail','employee_id', 'Training Details'),
                'medical_detail_ids':fields.many2one('hr.medical.detail', 'Medical Details')                                
               }

and

class hr_medical_detail(osv.osv):
    
    _name = 'hr.medical.detail'
    _rec_name = 'blood_group'    
    _columns = {
                'blood_group':fields.char('Please mention your blood group:', size=100, required=True),
                'medicine':fields.boolean('Are you taking any medicine?'),               
                'physician_address':fields.text('Please mention your physician name & address:')   
                                
               }

While saving medical details getting this error.

Please, can anyone tell what could be the reason?