Odoo: Two selection fields, second selection depends on the first selected value - odoo

Question

I have a model with two selection fields. In the first selection field the user chooses a project, and in second the user chooses a tranche, depends on the selected first field. (for one project, we have many tranche)
I use this declaration to my function:
#api.multi
#api.onchange('project')
def _get_tranche(self):
print res
return res`
If I'll print in console the result of returned value is correct, and I have exactly what I search, but in the view, the second field value does not displays computed values to choose after setting the second field value.
Is there any method to make it work properly?
This is my code:
#api.model
def _get_project(self):
values = {'$top' : 100,
'$filter' : "'name==:1&&parent==null'",
'$params' : '\'["*"]\'' }
response = requests.get('http://localhost:8081/rest/Project/name',
auth=('admin', 'admin'),
params=values)
data = response.json()
res = []
for record in data['__ENTITIES']:
res.append((record['__KEY'], record['name']))
return res
#property
def ret_value(self):
return self.project
#api.multi
#api.onchange('project')
def _get_tranche(self):
if self.ret_value == False:
return []
values = {'$top' : 100,
'$filter' : "'parent.ID==:1'",
'$params' : '\'[' + self.ret_value + ']\'' }
response = requests.get('http://localhost:8081/rest/Project/name',
auth=('admin', 'admin'),
params=values)
data = response.json()
res = []
for record in data['__ENTITIES']:
res.append((record['__KEY'], record['name']))
print res
return res
_columns = {
'name': fields.char("Name", required=True),
'description' : fields.text(),
'project' :fields.selection(selection=_get_project, string="Project"),
'tranche' : fields.selection(selection=_get_tranche, string="Tranche"),
}
NB: a tranche is a project with parent_id (not null) = id of a project, I need do the following: when I select a project X from the first field selection "project", I can select the tranches of this project (project with parent_id=X) from the second field selection "tranche" what I can't understand is the result of print in the console is correct, but in the view the field tranche is empty??!!
Now I am trying this:
_columns = {
'name': fields.char("Name", required=True),
'description' : fields.text(),
'project' :fields.selection(selection=_get_project, string="Project"),
'tranche' : fields.selection(selection=_get_tranche,
string="Tranche", compute='_return_tranche'),
}
#api.depends('project')
def _return_tranche(self):
if self.ret_value == False:
self.tranche = []
return
values = {'$top' : 100,
'$filter' : "'parent.ID==:1'",
'$params' : '\'[' + self.ret_value + ']\'' }
response = requests.get('http://localhost:8081/rest/Project/name',
auth=('admin', 'admin'),
params=values)
data = response.json()
res = []
for record in data['__ENTITIES']:
res.append((str(record['__KEY']),str(record['name'])))
print res
self.tranche = res
return
#api.model
def _get_tranche(self):
values = {'$top' : 100,
'$filter' : "'name==:1&&parent!=null'",
'$params' : '\'["*"]\'' }
response = requests.get('http://localhost:8081/rest/Project/name',
auth=('admin', 'admin'),
params=values)
data = response.json()
res = []
for record in data['__ENTITIES']:
res.append((record['__KEY'], record['name']))
return res
But I get this error
File "/opt/odoo/odoo/openerp/fields.py", line 1529, in convert_to_cache
raise ValueError("Wrong value for %s: %r" % (self, value))
ValueError: Wrong value for crm.lead.tranche: [('6', 'Tranche I'), ('7', 'Tranche II'), ('8', 'Tranche III')]
Help me please...