schema validation requires MappingSchema

[tisdall]

This is related to this posting on SO: http://stackoverflow.com/questions/30736627/cornice-schema-validation-with-colanderalchemy/30761861#30761861

Essentially validation will only work if the colander schema passed in is a direct subclass of MappingSchema. Using something like SchemaNode(typ=Mapping) should work just fine, but instead it throws cornice.schemas.SchemaError: schema is not a MappingSchema.

[almet]

Yeah, we definitely should do some duck typing here rather than trying to do a type check. I'm not sure from the thread on Stack Overflow: do you want to work on a fix?

[tisdall]

If you have time, I'd prefer it if you did. I'm a little swamped. I'm also just starting to figure out how Cornice works. ^_^

I'm going to fix ColanderAlchemy so it implements schema_type, but Cornice should probably be using typ as schema_type isn't really supposed to be used like that. I filed an issue at Pylons/colander#229 as that really is a hole waiting for other people to fall in.

[tisdall]

Okay, on second thought, I'm not going to make the change to ColanderAlchemy. The schema_type() is a static method so it has no access to the actual instance. When you use ColanderAlchemy it assigns a value to unknown of Mapping and schema_type won't ever see that. I think I could make it so schema_type() is no longer a static method, but then it's getting rather hackish.

I'll put together a PR to properly use the typ instead of schema_type() in Cornice.

[tisdall]

I'm going to close this issue as PR #309 fixes this issue.