[pylons-discuss] Deform/Colander: Mark deeply nested fields read-only after bind

[D.S. Ljungmark]

So, I've got a rather complex schema with several hierarchies deep. At the
lowest level, are a Sequence of Mappings as follows:


class Thingie(colander.MappingSchema):
name = colander.SchemaNode(
colander.String(),
missing=colander.required,
validator=name_validator,
)

port = colander.SchemaNode(
colander.String(),
missing=colander.required,
validator=validate_port,
)

class MidLevel(colander.MappingSchema):

@colander.instantiate(
missing=[],
title="Thingie definitions",
validator=colander.All(validate_unique_names,
validate_no_duped_ports))


class thingies(colander.SequenceSchema):
meter = Thingie(
title="Thingie",
)



Now, I'd want to make _new_ entries use a read/Write field for the name,
but turn it read-only when bound with data from the database backend. This
_seems_ at first view as if it should be a simple thing, but so far, I've
not succeeded.


I think I'm on a wrong track with binding, but I'm not sure where to go
here.

TL/DR:
How do I make a Sequence where already populated fields are Read Only, and
new fields permit user input?