JSON Schema Demystified: Dialects, Vocabularies and Metaschemas

Post by BerislavLopac » Sat, Nov 29, 2025, 10:58 AM UTC

magicalhippo wrote: post #25

I like JSON schema, but I haven't found any good tools to designing them. Or at least not a few years ago when I was looking. However, we already had an XMLSpy license, so decided to just stick with designing XSDs in XMLSpy and then just translate that to JSON Schema. If you make some small decisions, like value with attributes becomes an object, you can get a fairy decent subset of XSD to map 1:1 onto JSON Schema 20…

Post by BerislavLopac » Sat, Nov 29, 2025, 1:24 PM UTC

magicalhippo wrote: post #32

BerislavLopac wrote: post #31

Earlier quoted context omitted.

Yes, I've been searching for a long time for a good solution to allow non-coding people to visually design JSON Schemas. The closest thing I found is the schema editor in the amazing Stoplight service, but that is sadly not open source.

Heck, I'm a coder and I get lost when just dealing with the raw JSON Schema. It's not a problem for a dozen properties, but we have several hundreds in our larger schemas, even accounting for them being fairly normalized w.r.t. types. And five or more levels of nesting turns into an effective ten plus levels in the schema.

Post by magicalhippo » Sat, Nov 29, 2025, 4:51 PM UTC

BerislavLopac wrote: post #33

magicalhippo wrote: post #32

Earlier quoted context omitted.

Heck, I'm a coder and I get lost when just dealing with the raw JSON Schema. It's not a problem for a dozen properties, but we have several hundreds in our larger schemas, even accounting for them being fairly normalized w.r.t. types. And five or more levels of nesting turns into an effective ten plus levels in the schema.

One underutilised feature of JSON Schema is referencing external schemas and reusing them in multiple places, rather than copying them over and over again. The main hurdle to a better use of this feature is the lack of a good standard for schema repositories; I've been working on addressing this, but it's difficult to find the time. :/

Post by BerislavLopac » Sun, Nov 30, 2025, 4:33 PM UTC

magicalhippo wrote: post #35

BerislavLopac wrote: post #33

Earlier quoted context omitted.

One underutilised feature of JSON Schema is referencing external schemas and reusing them in multiple places, rather than copying them over and over again. The main hurdle to a better use of this feature is the lack of a good standard for schema repositories; I've been working on addressing this, but it's difficult to find the time. :/

> One underutilised feature of JSON Schema is referencing external schemas and reusing them in multiple places Yeah, though while it does make each subschema somewhat more readable and contained, you still don't get a good overview. If you're reading the spec for a given object, do you don't easily see where it's being used in the schema. For now I've just supplied the JSON Schema as a self-contained thing, and defer…

Post by eternityforest » Sun, Nov 30, 2025, 6:28 PM UTC

gregsdennis wrote: post #17

stabbles wrote: post #15

The metaschemas are useful but not strict enough. They don't set `additionalProperties: false`, which is great if you wanna extend the schema with your own properties, but it won't catch simple typos. For example, the following issues pass under the metaschema. {"foo": {"bar": { ... }}} # wrong {"foo": {"type": "object", "properties": {"bar": { ... }}}} # correct {"additional_properties": false} # wrong {"additionalP…

This is intentional because unknown keywords are permitted with JSON Schema 2020-12 and prior. We are changing this with the upcoming version, which means we'll be updating the meta-schema to enforce it as well.