What limits are placed on names in $defs and data type names?

[sjlongland]

Hi all,

This is a bit of a silly question, but a cursory read of the draft RFC for JSONSchema and various documentation items has thus far not answered it for me.

What names are valid in the name of a $defs member or the name used in a field data type?

My intended use case is to basically be able to describe a SQL database tables through JSONSchema documents. The goal being a kind-of HTTP-based ORM, which coupled with a suitably specified ReST API specification and using JSONSchema-based form generators for the front-end, would pretty much give you a pretty powerful declarative ORM web-application framework without having to write much in the way of SQL or JavaScript/HTML code.

Specifically I'd like to be able to encode both "generic" types (e.g. string, number, integer…) and more specific types; e.g. maybe postgres:ltree for a PostgreSQL ltree column -- so that basically the type name is "scoped", and won't clash with anyone else's data types.

Are there any gotchas I need to be aware of?

[handrews]

Interesting! I'm doing something similar (I think) with Apache Tinkerpop's Gremlin query language for graph databases.

You might want to bring this discussion to the Slack discussion.

$defs names are just JSON object names and can be anything that is syntactically legal in that sense. Of course, some names will require URI-encoding to be used in JSON Pointer fragments, but if you're using a proper implementation of JSON Pointer and constructing URIs with a proper URI library, that won't be an issue.

I'm not sure what you mean by "name used in a field data type"? The type keyword is not extensible.

[sjlongland]

Ahh right, so for $defs names, if I stick to what can be sanely URI-encoded I should be fine.

And understood regarding type, can I put other annotations alongside the $defs to further refine the data type? e.g. if I do

{
  "$id": "https://example.com/blog-category.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "description": "An example of a blogging category",
  "type": "object",
  "properties": {
    "category-id": {
      "$ref": "#/$defs/postgres-uuid"
    },
    "category-path": {
      "$ref": "#/$defs/postgres-ltree"
    },
    "name": {
      "type": "string"
    }
  },
  "$defs": {
     "postgres-uuid": {
         "type": "string",
         "columnType": "uuid",
         "displayFormat": "base64"
     },
     "postgres-ltree": {
         "type": "string",
         "columnType": "ltree"
     }
  }
}

… that columnType and displayFormat value will be associated with the category-id and category-path fields defined in the object?