fix some bugs

contract.py

@@ -89,7 +89,7 @@ class AgronomicsContract(Workflow, ModelSQL, ModelView):
         return 'draft'
 
     def get_rec_name(self, name):
-        ret = self.producer.rec_name
+        ret = self.producer and self.producer.rec_name or ''
         if self.start_date:
             ret += ' - %s' % (self.start_date)
         return ret

plot.py

@@ -143,7 +143,7 @@ class Parcel(ModelSQL, ModelView):
             )*self.surface, 2)
 
     def get_purchased_quantity(self, name):
-        return sum([w.netweight for w in self.weighings if not w.table])
+        return sum([w.netweight for w in self.weighings if not w.table and w.netweight])
 
     def get_remaining_quantity(self, name):
         return (self.max_production or 0) - (self.purchased_quantity or 0)

weighing.py

@@ -355,6 +355,7 @@ class Weighing(Workflow, ModelSQL, ModelView):
         WeighingParcel = pool.get('agronomics.weighing-agronomics.parcel')
         weighing_parcel_to_save = []
         to_analysis = []
+
         for weighing in weighings:
             if not weighing.table:
                 if weighing.parcels:
@@ -380,8 +381,10 @@ class Weighing(Workflow, ModelSQL, ModelView):
                     else:
                         remaining_weight -= parcel.remaining_quantity
                         weighing_parcel.netweight = parcel.remaining_quantity
+
                     if weighing_parcel.netweight:
                         weighing_parcel_to_save.append(weighing_parcel)
+
                 if remaining_weight == 0:
                     to_analysis.append(weighing)
             else: