Allow customizing SQL expression of field

trytond/CHANGELOG

@@ -1,3 +1,4 @@
+* Add support for column_<field name> method
 * Use tables and Model as arguments for sql_column of the Field
 * Add support for basic authentication for user application
 * Support the conversion of MJML reports to HTML

trytond/doc/ref/fields.rst

@@ -222,6 +222,17 @@ Default value
 
 See :ref:`default value <topics-fields_default_value>`
 
+Reading
+=======
+
+A class method could be defined for each field which must return a SQL
+expression as column instead of the default one.
+The method signature is::
+
+   column_<field name>(tables)
+
+Where ``tables`` is a nested dictionary, see :ref:`tables <ref-tables>`.
+
 Searching
 =========
 

trytond/trytond/model/fields/field.py

@@ -206,6 +206,16 @@ def on_change_with_result(fieldname):
     return decorator
 
 
+def column_method(func):
+    @wraps(func)
+    def wrapper(self, tables, Model):
+        method = getattr(Model, f'column_{self.name}', None)
+        if method:
+            return method(tables)
+        return func(self, tables, Model)
+    return wrapper
+
+
 def domain_method(func):
     @wraps(func)
     def wrapper(self, domain, tables, Model):
@@ -421,6 +431,7 @@ class Field(object):
     def sql_cast(self, expression):
         return Cast(expression, self.sql_type().base)
 
+    @column_method
     def sql_column(self, tables, Model):
         table, _ = tables[None]
         return Column(table, self.name)

trytond/trytond/tests/test_tryton.py

@@ -655,7 +655,7 @@ class ModuleTestCase(_DBTestCase):
         def test_methods(mname, model, attr):
             for prefixes in [['default_'],
                     ['on_change_', 'on_change_with_'],
-                    ['order_'], ['domain_'], ['autocomplete_']]:
+                    ['column_'], ['order_'], ['domain_'], ['autocomplete_']]:
                 if attr in {'on_change_with', 'on_change_notify'}:
                     continue
                 # TODO those method should be renamed