Access inherited field of a model from a view - odoo

Question

I'm working on OpenERP7, trying to access a related field located in a parent model of said related model. If someone at this point understand something, you're way smarter than I am, so i will just put the example of what i'm trying to achieve :
My model :
class trench(osv.osv):
_name = 'trench'
_inherit = 'common'
_columns = {
'trench_lines': fields.one2many('trench.line', 'trench_id', 'Trench Lines'),
'trench_depth': fields.one2many('trench.depth', 'trench_id', 'Trench Depth'),
}
trench()
class trench_common(osv.osv):
_name = 'trench.common'
def compute_vals(self, cr, uid, ids, field_name, arg, context):
...
def on_change_values(self, cr, uid, ids, context=None):
...
_columns = {
'trench_id': fields.many2one('trench', 'Trench', ondelete='cascade', required=True),
'length' : fields.function(compute_vals, type='float', string="Length", method=True, store=True),
}
trench_common()
class trench_line(trench_common):
_name = 'trench.line'
_inherit = 'trench.common'
trench_line()
class trench_dig_common(trench_common):
_name = 'trench.dig.common'
_inherit = 'trench.common'
_columns = {
'length' : fields.float('Length', digits=(6,3)),
'height' : fields.float('Height', digits=(6,3)),
'total_m3' : fields.float('Total m3', digits=(6,3)),
'observation' : fields.text('Observation'),
}
trench_dig_common()
class trench_depth(trench_dig_common):
_name = 'trench.depth'
_inherit = 'trench.common'
trench_depth()
My view :
<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>
<record id="trench_form" model="ir.ui.view">
<field name="name">trench.form</field>
<field name="model">trench</field>
<field name="inherit_id" ref="common_form" />
<field name="arch" type="xml">
<group string="Worksite" position="after">
<separator string="Progress" />
<field name="trench_lines">
<tree editable="bottom">
<field name="length"/>
</tree>
</field>
<separator string="Cumulate Length" />
<field name="total_length"/>
<separator string="Trench Particularity" />
<notebook>
<page string="Surdepth">
<field name="trench_depth">
<tree editable="bottom">
<field name="height"/>
</tree>
</field>
</page>
</notebook>
</group>
</field>
</record>
</data>
</openerp>
My error :
except_orm: ('View error', u"Can't find field 'height' in the following view parts composing the view of object model 'qhse.trench':\n * trench.form\n\nEither you wrongly customized this view, or some modules bringing those views are not compatible with your current data model")
2015-05-21 07:56:28,631 13918 ERROR ahak_production openerp.tools.convert: Parse error in trench_view.xml:4:
So, i'm figuring i can't access a field of a model with so many layers, but is there a way to achieve this, and if so, how? I'm trying to make something DRY, but always end up duplicating code with OpenERP.
Thanks for reading.

Answer 1

You need to define your last class as below.
class trench_depth(trench_dig_common):
_name = 'trench.depth'
_inherit = 'trench.dig.common'
trench_depth()
Then after you can access all fields which are available inside "trehch.dig.common" model.