Hello Ahmed M.Elmubarak,

Usually, if you want to access the current value of context, you have to add the variable : context, in your xml view, for example : 

<field name"=your_field" on_change="your_onchange_method(field1, field2, context)"/>

Assuming that field1 and field2 are present in your model AND in your current view (as it supplies the current value of those fields, eventually modified by the user, not their actual stored value in db). 

Finally, your method may have the following signature to be usable: 

def your_onchange_method(self, cr, uid, ids, field1, field2, context): 

    # ids has no value, but has to be present

Hope it helps you,

Regards