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JSON Schema Core, $dynamicAnchor, and $vocabulary

Aabi4/21/2023
Slightly off-topic, but I'm writing a Deno library. Anyone deeply knowledgeable on JSON Schema Core? I have this meta-schema, and I can't figure out how the heck it's supposed to work that "$ref": "meta/core" would refer to "https://json-schema.org/draft/2020-12/vocab/core" – any ideas? I feel like I'm missing something fundamental knowledge on the JSON Schema Core spec here...
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"$id": "https://json-schema.org/draft/2020-12/schema",
"$vocabulary": {
"https://json-schema.org/draft/2020-12/vocab/core": true,
"https://json-schema.org/draft/2020-12/vocab/applicator": true,
"https://json-schema.org/draft/2020-12/vocab/unevaluated": true,
"https://json-schema.org/draft/2020-12/vocab/validation": true,
"https://json-schema.org/draft/2020-12/vocab/meta-data": true,
"https://json-schema.org/draft/2020-12/vocab/format-annotation": true,
"https://json-schema.org/draft/2020-12/vocab/content": true
},
"$dynamicAnchor": "meta",
"title": "Core and Validation specifications meta-schema",
"allOf": [
{"$ref": "meta/core"},
{"$ref": "meta/applicator"},
{"$ref": "meta/unevaluated"},
{"$ref": "meta/validation"},
{"$ref": "meta/meta-data"},
{"$ref": "meta/format-annotation"},
{"$ref": "meta/content"}
],
...
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"$id": "https://json-schema.org/draft/2020-12/schema",
"$vocabulary": {
"https://json-schema.org/draft/2020-12/vocab/core": true,
"https://json-schema.org/draft/2020-12/vocab/applicator": true,
"https://json-schema.org/draft/2020-12/vocab/unevaluated": true,
"https://json-schema.org/draft/2020-12/vocab/validation": true,
"https://json-schema.org/draft/2020-12/vocab/meta-data": true,
"https://json-schema.org/draft/2020-12/vocab/format-annotation": true,
"https://json-schema.org/draft/2020-12/vocab/content": true
},
"$dynamicAnchor": "meta",
"title": "Core and Validation specifications meta-schema",
"allOf": [
{"$ref": "meta/core"},
{"$ref": "meta/applicator"},
{"$ref": "meta/unevaluated"},
{"$ref": "meta/validation"},
{"$ref": "meta/meta-data"},
{"$ref": "meta/format-annotation"},
{"$ref": "meta/content"}
],
...
IioB4/21/2023
Isn't the vocab and the allOf aligned one-to-one? JSON is ordered mostly by insertion time so it seems pretty easy to match the two up.
Aabi4/21/2023
>Isn't the vocab and the allOf aligned one-to-one? i mean... yes, but the syntax in each $ref seems completely arbitrary. the json schema core spec doesn't say anything about such a syntax that i'm aware. https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-00#appendix-D.2
IETF Datatracker
JSON Schema: A Media Type for Describing JSON Documents
JSON Schema defines the media type "application/schema+json", a JSON- based format for describing the structure of JSON data. JSON Schema asserts what a JSON document must look like, ways to extract information from it, and how to interact with it. The "application/ schema-instance+json" media type provides additional feature-rich integration wi...
Aabi4/21/2023
from the link:
...
"$dynamicAnchor": "meta",
"$vocabulary": {
"https://json-schema.org/draft/2020-12/vocab/core": true,
"https://json-schema.org/draft/2020-12/vocab/applicator": true,
"https://json-schema.org/draft/2020-12/vocab/validation": true,
"https://example.com/vocab/example-vocab": true
},
"allOf": [
{"$ref": "https://json-schema.org/draft/2020-12/meta/core"},
{"$ref": "https://json-schema.org/draft/2020-12/meta/applicator"},
...
...
"$dynamicAnchor": "meta",
"$vocabulary": {
"https://json-schema.org/draft/2020-12/vocab/core": true,
"https://json-schema.org/draft/2020-12/vocab/applicator": true,
"https://json-schema.org/draft/2020-12/vocab/validation": true,
"https://example.com/vocab/example-vocab": true
},
"allOf": [
{"$ref": "https://json-schema.org/draft/2020-12/meta/core"},
{"$ref": "https://json-schema.org/draft/2020-12/meta/applicator"},
...
hm, i think i get it now. "$id": "https://json-schema.org/draft/2020-12/schema", this identifies the URI of the schema itself. so then the relative URI meta/core becomes: https://json-schema.org/draft/2020-12/meta/core which is what's actually being $ref'd here. the vocabulary URI's themselves aren't actually schemas, more like unique identifiers.

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