$dynamicAnchor inside propertyDependencies

[gregsdennis]

propertyDependencies is a conditional keyword. Similarly to if/then/else, you can repeat a $dynamicAnchor inside multiple branches, and $dynamicRef should be able to find the right one.

[handrews]

This is a bit tricky b/c $dynamicAnchor has resource-level effects, not just schema object level. Repeating the same anchor in different keyword branches would have undefined behavior because there would be multiple valid resolution targets.

[gregsdennis]

Repeating the same anchor in different keyword branches would have undefined behavior because there would be multiple valid resolution targets.

We have tests that do exactly this already with if/then/else:

JSON-Schema-Test-Suite/tests/draft2020-12/dynamicRef.json

Lines 352 to 398 in 716b95d

	{
	"description": "multiple dynamic paths to the $dynamicRef keyword",
	"schema": {
	"$schema": "https://json-schema.org/draft/2020-12/schema",
	"$id": "https://test.json-schema.org/dynamic-ref-with-multiple-paths/main",
	"$defs": {
	"inner": {
	"$id": "inner",
	"$dynamicAnchor": "foo",
	"title": "inner",
	"additionalProperties": {
	"$dynamicRef": "#foo"
	}
	}
	},
	"if": {
	"propertyNames": {
	"pattern": "^[a-m]"
	}
	},
	"then": {
	"title": "any type of node",
	"$id": "anyLeafNode",
	"$dynamicAnchor": "foo",
	"$ref": "inner"
	},
	"else": {
	"title": "integer node",
	"$id": "integerNode",
	"$dynamicAnchor": "foo",
	"type": [ "object", "integer" ],
	"$ref": "inner"
	}
	},
	"tests": [
	{
	"description": "recurse to anyLeafNode - floats are allowed",
	"data": { "alpha": 1.1 },
	"valid": true
	},
	{
	"description": "recurse to integerNode - floats are not allowed",
	"data": { "november": 1.1 },
	"valid": false
	}
	]
	},

[gregsdennis]

I'm working up a PR to illustrate a non-conflicting way that this could work.

[gregsdennis]

I don't understand why you're saying it's undefined behavior.

Consider the schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "http://localhost:1234/draft2020-12/dynamicanchor-in-propertydependencies.json",
  "$defs": {
    "inner": {
      "$id": "inner",
      "$dynamicAnchor": "foo",
      "type": "object",
      "additionalProperties": {
        "$dynamicRef": "#foo"
      }
    }
  },
  "propertyDependencies": {
    "expectedTypes": {
      "strings": {
        "$id": "east",
        "$dynamicAnchor": "foo",
        "type": "string",
        "$ref": "inner"
      },
      "integers": {
        "$id": "west",
        "$dynamicAnchor": "foo",
        "type": "integer",
        "$ref": "inner"
      }
    }
  }
}

It's pretty clear to me that /propertyDependencies/expectedTypes/integers is only in dynamic scope when the instance has "expectedTypes": "integers". Only one subschema in the /propertyDependencies/expectedTypes branch could be active at once.

Yes, you could have that anchor spread across multiple properties, and that would be invalid/undefined.

{
  ...,
  "propertyDependencies": {
    "expectedTypes": {
      "strings": {
        "$id": "east",
        "$dynamicAnchor": "foo",
        "type": "string",
        "$ref": "inner"
      },
      "integers": {
        "$id": "west",
        "$dynamicAnchor": "foo",
        "type": "integer",
        "$ref": "inner"
      }
    },
    "anotherProp": {
      "valueA": {
        "$id": "north",
        "$dynamicAnchor": "foo",
        "type": "string",
        "$ref": "inner"
      },
      "valueB": {
        "$id": "south",
        "$dynamicAnchor": "foo",
        "type": "integer",
        "$ref": "inner"
      }
    }
  }
}

But the first schema doesn't do that.

[gregsdennis]

I could also write

{
  "anyOf": [
    {
      "$dynamicAnchor": "foo",
      "type": "integer"
    },
    {
      "$dynamicAnchor": "foo",
      "type": "string"
    }
  ]
}

I would say that this is perfectly valid, but the behavior is undefined. It doesn't prevent us from having tests for the defined cases.

[handrews]

Because it's not the object-level dynamic scope, it's the resource-level dynamic scope. Read json-schema-org/json-schem-spec#1140 if you want the gory details.

[handrews]

For that matter, since we haven't actually made the changes in issue 1140, this is even simpler: These schemas produce the same URI for different schema locations, and that results in undefined behavior (URI fragments are resource scoped, it doesn't matter whether the specific object is in the dynamic scope or not).

[handrews]

Ah, my mistake- the allOf one is undefined, but you're correct, you have $id in the right places in the actual test, my apologies.