Is there a way to define the format attribute?

[sciutand]

Json schema has a 'format' keyword. Is this supported by mson? I couldn't find any reference

http://json-schema.org/latest/json-schema-validation.html#anchor104

[pksunkara]

@sciutand I don't think we support it yet.

[zdne]

@sciutand not at this moment no. I was thinking about adding some validations to MSON. Can you please elaborate a bit? What is the particular validation you are looking for?

[geemus]

@zdne some I have found useful would be email and uuid (though I think we defined uuid ourselves with a regex). Additionally something like datetime for iso8601 timestamp strings is really helpful.

[zdne]

Thanks for the input!

I would like to keep collecting the feedback on this and then implement the most requested format / validators based on that.

[geemus]

Sure, in addition to those, I think all the ones from json-schema validation spec are handy: date-time, email, hostname, ipv4, ipv6, and uri.

[kevinswiber]

I'm currently looking to do this with uri. 👍

[zdne]

... so basically all of the predefined validations 😎

[jmatsushita]

Hi there,

Do note that the spec says MAY add custom format attributes. so I think it does make sense to have a syntax which allows adding an arbitrary format in MSON. Given that any keyword with the format key seems valid, it seems that MSON only needs a syntax that would allow for that, and doesn't need to define anything particular about each format and can delegate to JSON Schema validators to take care of interpreting the format values. Unless I'm missing something.

The popular ajv for instance validates the spec formats and a few more: https://github.com/epoberezkin/ajv#formats

Also check out the v5 proposal implemented in ajv for much more general way to implement validations.

Anyway, getting back to the topic.

Proposal for format syntax in MSON.

Here a proposal for a format syntax in MSON which would generate the following schema:

{ '$schema': 'http://json-schema.org/draft-04/schema#',
  type: 'object',
  properties: { prop: { type: 'string' } } }

So the following data should validate:

{ 
 "prop": "1985-04-12T23:20:50.52Z"
}

Proposal: Use []

# format
- `prop`: `1985-04-12T23:20:50.52Z` (string[date-time])

The advantage of this over other variations I've tried is that it's valid MSON and drafter returns it as a simple string.

{ '$schema': 'http://json-schema.org/draft-04/schema#',
  type: 'object',
  properties: { prop: { type: 'string' } } }

The square brackets [] are used for Nested Member Types and Generics for Structure Types, so not used for primitive types. Although the spec doesn't seem to specify this, format seems to only apply to the string primitive.

What do you think?

Cheers,

Jun

[zdne]

Hey @jmatsushita,
thanks for your detailed reply! Definitely good pointers there!

We have originally intended to use the validation (validations) keyword for format validation. See the stub here https://github.com/apiaryio/mson/blob/master/MSON%20Specification.md#46-validations

So in the case of string[date-time] I would rather see a custom type with validations. Eg.

# Date Type (string)
This is a description

## Validations
...

## Sample
1985-04-12T23:20:50.52Z

Note this is not valid syntax at this moment..

[jmatsushita]

That sounds good! I guess that would mean you'd have some predefined validations for the formats in the JSON Schema spec? date-time, email, hostname, ipv4, ipv6, and uri ?

[zdne]

@jmatsushita could be, see #43 (comment)

[namoscato]

Any update on plans to support JSON schema's defined formats? I am particularly interested in date-time but see no reason why others should not also be supported.

[alangibson-philips]

Are there any plans to support this? It would be nice to have a firm statement, even if it's "no."

[pksunkara]

Definitely yes. But we can't give an ETA.