It's not neccesary to send the field2, you can do this:

class my_class(osv.osv):

_name = "my.class"

_columns = {
    'field1': fields.selection([('1', 'A'), ('1', 'B')], 'my filed 1'),
    'field2': fields.boolean('My field 2'),
}

def onchange_field1(self, cr, uid, ids, field1):
    if field1=='1':
        v = {'field2': True}
        return {'value': v}
    return {}

res_partner()

in xml file :

<field name="field1" on_change="onchange_field1(field1)"/>
<field name="field2"/>

As you can see you have to compare field1 with the key not with the name

Hello,

I need to change my slection elements after change field1 .

this code doesn't work , who has an idea how to fix it ?

_columns = {
'field1': fields.selection([('1', 'A'), ('1', 'B')], 'my filed 1'),
'field2': fields.selection([('aa', 'C'), ('bb', 'D')], 'my filed 2'),
}
def onchange_field2(self, cr, uid, ids,field1,context=None):
    lst= [('5', '5'), ('6', '6'), ('7', '7'), ('8', '8')]
    try:
        lst.remove([item for item in lst if item[0] == '5'][0])
    except IndexError as e:
        pass
    v = {'field2': lst}
    return {'value': v}

thank you

What if I have to change string of boolean field instead of value?How will I then achieve?