i want to acccess a one2many field in the onchange event of the corresponding many2one field.

I have defined 2 Models:

class model_a(osv.osv_memory):
    _name = "model.a"
    _columns = {'b_ids' : fields.one2many('model.b', 'a_id')}
    
    @api.onchange('b_ids')
    def test(self):
        print "Onchange Function model.a"
        for line in self.b_ids:
            print line.field1
        
class model_b(osv.osv_memory):
    _name = "model.b"
    _columns = {'a_id' : fields.many2one('model.a'),
                'field1' : fields.char('field1')}
    
    @api.onchange('field1', 'a_id')
    def test(self):
        print "Onchange Function model.b"
        for line in self.a_id.b_ids:
            print self.a_id
            print line.field1

There is a view where you can edit the List:

        <record id="model_a_tree_view" model="ir.ui.view">
            <field name="name">model_a_tree_view</field>
            <field name="model">model.a</field>
            <field name="type">form</field>
            <field name="arch" type="xml">
                <form string="Test">
                <group >
                    <group colspan="4">
                        <field name="b_ids" widget="one2many_list" colspan="4">
                            <tree string="b_s" editable="bottom"  >
                            	<field name="a_id" invisible="1"  />
                                <field name="field1"  /> 
                            </tree>
                        </field>
                    </group>
                </group>
                </form>
            </field>
        </record>

I expected to see all model.b entries in the one2many field b_ids. Instead i get only the current entry.

I could use the onchange funtion of  model.a field b_ids, but i cant see wich line has changed and i would have to revalidate all entries.

Output 1st Element added (the field1 text is still blank):

Onchange Function model.a
Onchange Function model.b
model.a(<openerp.models.NewId object at 0xad20f3ec>,)
False

Output 1st Element added (field1 = Test 1):

Onchange Function model.b
model.a(<openerp.models.NewId object at 0xad21658c>,)
Test 1
Onchange Function model.a
Test 1

Everything works like excpected so far. If i add another element (field1 = Test 2) the onchange function in Model b cant see the first entry:

Onchange Function model.b
model.a(<openerp.models.NewId object at 0xad2298ac>,)
Test 2
Onchange Function model.a
Test 1
Test 2

In the onchange function for model.a self.b_ids is:

b: model.b(<openerp.models.NewId object at 0xad1c73ec>, <openerp.models.NewId object at 0xad1c7b6c>)

in the onchange function for model.b self.a_id.b_ids is:

b: model.b(<openerp.models.NewId object at 0xad1d3b6c>,)

Is it possible to see all entries in the onchange function for field1 or see wich item was modified in the onchange function for a one2many field (including new lines without id)?