get last item on One2Many

[Francisco Maria Moyano Casco]

Hello.
          I need to use the last element of a One2Many field. Is there any function to do that?

          Thanks
                  Francisco

[Cédric Krier]

On 2016-05-27 11:04, Francisco Maria Moyano Casco wrote:
> Hello.
> I need to use the last element of a One2Many field. Is there any
> function to do that?

You can use negative index -1
See point 3 of
https://docs.python.org/2/library/stdtypes.html#sequence-types-str-unicode-list-tuple-bytearray-buffer-xrange

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Cédric Krier - B2CK SPRL
Email/Jabber: cedric...@b2ck.com
Tel: +32 472 54 46 59
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[Francisco Maria Moyano Casco]

Yes, I tried to, but I got an error.

Maybe is because I'm using Tryton-3.4?

[Cédric Krier]

On 2016-05-27 12:28, Francisco Maria Moyano Casco wrote:
> Yes, I tried to, but I got an error.

It is not clear what you have tried.
Also if you want us to help you, you must provide more information.
What was the code you tried? What was the error? etc.


PS: Please don't top-post on this mailing list, see
http://groups.tryton.org/netiquette

[Francisco Maria Moyano Casco]

Sorry, my last message was rejected for top-posting.

I already solved it aided by friends from Silix.

It is not clear what you have tried.
Also if you want us to help you, you must provide more information.
What was the code you tried? What was the error? etc.

I tried to used negative index -1

(....)
    housing_conditions = fields.One2Many('gnuhealth.housing','du',
            'Housing Conditions')
   
    critical_housing = fields.Function(fields.Boolean('Vivienda Critica'),
        'get_critical_housing',searcher='search_critical_housing')

    @classmethod
    def search_critical_housing(cls,name,clause):
      res = []
      value = clause[2]
      if(cls.housing_conditions._get_size()!=0):
         this_one = cls.housing_conditions[-1].critical_housing
         res.append(('this_one',clause[1],value))
      return res
(....)

And gave me this error:

(...)
 File "/trytond/model/modelsql.py", line 1146, in convert
    expression = field.convert_domain(domain, tables, cls)
  File "/trytond/model/fields/function.py", line 64, in convert_domain
    return getattr(Model, self.searcher)(name, domain)
  File "/trytond/modules/z_DU/health.py", line 46, in search_critical_housing
    this_one = cls.housing_conditions[-1].critical_housing
TypeError: 'One2Many' object does not support indexing
(...)


I could solved with this

    @classmethod
    def search_critical_housing(cls, name, clause):
         cursor = Transaction().cursor
         pool = Pool()
         DomiciliaryUnit = pool.get('gnuhealth.du')
         HousingConditions = pool.get('gnuhealth.housing')
         cursor.execute('SELECT du.id '
             'FROM "' + DomiciliaryUnit._table + '" du '
                 'INNER JOIN ( '
                     'SELECT DISTINCT ON (du) du, critical_housing '
                     'FROM "' + HousingConditions._table + '" '
                     'ORDER BY du, id DESC '
                 ') last_hc '
                 'ON du.id = last_hc.du '
             'WHERE last_hc.critical_housing = TRUE')
         has_critical_housing = cursor.fetchall()
         field, op, operand = clause
         if (op, operand) in (('=', True), ('!=', False)):
             return [('id', 'in', has_critical_housing)]
         elif (op, operand) in (('=', False), ('!=', True)):
             return [('id', 'not in', has_critical_housing)]
         else:
             return []


Thanks anyway :) !!!

             Francisco