[pylons-discuss] Deform/Colander: Marking fields as read-only

[D.S. Ljungmark]

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


I have 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 ( using `bind`),
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.


Any suggestions would be welcome.

[Dennis Ljungmark]

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


I have 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 ( using `bind`),
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.


Any suggestions would be welcome.

( Please excuse using the web form, seems my email subscription is held for
moderation)

[Mike Orr]

I don't know how you'd integrate it with Colander, but generally you'd
use a dict subclass with a __setitem__ method that raises an exception
for read-only keys. Lists and classes can do something similar.

How do I make a Sequence where already populated fields are Read Only, and new fields permit user input?
name = colander.SchemaNode(
colander.String(),
missing=colander.required,
validator=name_validator,
)
port = colander.SchemaNode(
colander.String(),
missing=colander.required,
validator=validate_port,
)
@colander.instantiate(
missing=[],
title="Thingie definitions",
validator=colander.All(validate_unique_names,
validate_no_duped_ports))
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 ( using `bind`), 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.
Any suggestions would be welcome.
( Please excuse using the web form, seems my email subscription is held for moderation)
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