issue #5 Add set_pyafipws_concept method.

Also, refactor method on_change_pos for other tryton-ar modules.

invoice.py

@@ -376,13 +376,22 @@ def on_change_reference(self):
 
     @fields.depends('pos', 'party', 'type', 'company')
     def on_change_pos(self):
-        PosSequence = Pool().get('account.pos.sequence')
-
         if not self.pos:
             self.invoice_type = None
             return
+        self._set_invoice_type_sequence()
+
+    def _set_invoice_type_sequence(self):
+        '''
+        Set invoice type field.
+        require: pos field must be set first.
+        '''
+        if not self.pos:
+            return
 
+        PosSequence = Pool().get('account.pos.sequence')
         client_iva = company_iva = None
+
         if self.party:
             client_iva = self.party.iva_condition
         if self.company:
@@ -408,15 +417,35 @@ def on_change_pos(self):
             (self.type, kind)
             ]
         sequences = PosSequence.search([
-            ('pos', '=', self.pos.id),
+            ('pos', '=', self.pos),
             ('invoice_type', '=', invoice_type)
             ])
         if len(sequences) == 0:
             self.raise_user_error('missing_sequence', invoice_type_desc)
         elif len(sequences) > 1:
             self.raise_user_error('too_many_sequences', invoice_type_desc)
         else:
-            self.invoice_type = sequences[0].id
+            self.invoice_type = sequences[0]
+
+    def set_pyafipws_concept(self):
+        '''
+        set pyafipws_concept researching the product lines.
+        '''
+        products = {'1': 0, '2': 0}
+        self.pyafipws_concept = ''
+        for line in self.lines:
+            if line.product:
+                if line.product.type == 'goods':
+                    products['1'] += 1
+                if line.product.type == 'service':
+                    products['2'] += 1
+
+        if products['1'] != 0 and products['2'] != 0:
+            self.pyafipws_concept = '3'
+        elif products['1'] != 0:
+            self.pyafipws_concept = '1'
+        elif products['2'] != 0:
+            self.pyafipws_concept = '2'
 
     def _credit(self):
         pool = Pool()