Delete read data after having instantiated all targets

Some read value may be needed to instantiate other records if it is used in the
context.
Also the test to fill fields dictionary was always false as it tested the field
instance instead of the name.

issue9380
review298171002

trytond/model/modelstorage.py

@@ -1464,9 +1464,10 @@ class ModelStorage(Model):
         # add datetime_field
         for field in list(ffields.values()):
             if hasattr(field, 'datetime_field') and field.datetime_field:
-                datetime_field = self._fields[field.datetime_field]
-                ffields[field.datetime_field] = datetime_field
                 require_context_field = True
+                if field.datetime_field not in ffields:
+                    datetime_field = self._fields[field.datetime_field]
+                    ffields[field.datetime_field] = datetime_field
 
         # add depends of field with context
         for field in list(ffields.values()):
@@ -1475,9 +1476,9 @@ class ModelStorage(Model):
                 for context_field_name in eval_fields:
                     if context_field_name not in field.depends:
                         continue
-                    context_field = self._fields.get(context_field_name)
                     require_context_field = True
-                    if context_field not in ffields:
+                    if context_field_name not in ffields:
+                        context_field = self._fields.get(context_field_name)
                         ffields[context_field_name] = context_field
 
         def filter_(id_):
@@ -1569,6 +1570,7 @@ class ModelStorage(Model):
             # create browse records for 'remote' models
             for data in read_data:
                 id_ = data['id']
+                to_delete = set()
                 for fname, field in ffields.items():
                     fvalue = data[fname]
                     if field._type in {
@@ -1583,8 +1585,9 @@ class ModelStorage(Model):
                             or field.context
                             or getattr(field, 'datetime_field', None)
                             or isinstance(field, fields.Function)):
-                        del data[fname]
-                self._cache[id_]._update(data)
+                        to_delete.add(fname)
+                self._cache[id_]._update(
+                    **{k: v for k, v in data.items() if k not in to_delete})
         return value
 
     @property