Allow for subclassed types

[mkrizek]

A little background first, in Ansible there is a json_query filter plugin which uses jmespath to query json. There is an issue open where users of that plugin get the following error:

JMESPathTypeError: In function contains(), invalid type for value: irb.1111, expected one of: ['array', 'string'], received: "unknown"

The comment that summarizes the issue is here ansible/ansible#27299 (comment).

The error is caused by the fact that Ansible uses its own types for strings. One of the hacks we've come up with was:

jmespath.functions.REVERSE_TYPES_MAP['string'] = jmespath.functions.REVERSE_TYPES_MAP['string'] + ('AnsibleUnicode', 'AnsibleUnsafeText',)

which seems weird since I am pretty sure REVERSE_TYPES_MAP is not supposed to be public.

is there a proper way to do this? If not, is this something that would be considered to be added?

Thanks!

[mkrizek]

cc @jamesls

[jamesls]

There's not a good way to do this now throuhg a public interface but I'm not opposed to adding something to make this easier. Having less restrictive type checking has come up a few times.

[jeking3]

@jamesls would you be able to add this public interface that allows the consumer of jmespath to teach jmespath about additional types that are convertible to string? Or do you need someone in the community to do it?

[jeking3]

@jamesls are you still there?

[jamesls]

So I'm not opposed to this feature, but offhand I don't have any thoughts on a better public API for this. If anyone has suggestions, I'm open to it. I suppose we'd add something to the Options class?

Once we have an interface we like, I can take a crack at implementing this.