Linter: create rule to remove additional items when items is an object #1805

Karan-Palan · 2025-07-02T22:43:31Z

Implementation

Rule ID: dangling_additional_items
Description: "additionalItems is ignored when items is an object"
Condition: Detects additionalItems in JSON Schema objects where items is an object (not an array).
Transform: Removes the redundant additionalItems property.
Dialects: Supports draft4, draft6, draft7, and 2019-09. Excluded for draft-2020-12 (where additionalItems was removed from the spec).

Registered the rule in the Common rules section (correctness category).
Added 10 test cases across all relevant JSON Schema drafts.

Test Cases

Positive Cases: Removal of additionalItems when items is an object.
Negative Cases: No change for items as an array or when items is undefined.
Edge Cases: Complex items objects (e.g., with if/then conditions) - correctly handled.
Context Preservation: Tests with various other keywords to ensure proper behavior.

…en items is an objects Signed-off-by: karan-palan <karanpalan007@gmail.com>

jviotti · 2025-07-03T18:26:45Z

src/extension/alterschema/alterschema.cc

@@ -52,6 +52,7 @@ static auto every_item_is_boolean(const T &container) -> bool {
 #include "linter/content_media_type_without_encoding.h"
 #include "linter/content_schema_default.h"
 #include "linter/content_schema_without_media_type.h"
+#include "linter/dangling_additional_items.h"


Can we all it additional_items_with_schema_items? The dangling part seems confusing at first and other rules follow the with and without convention. I think additional_items_with_schema_items is still short enough and very self-explanatory

Also, you have to update the CMakeLists.txt file to list this file too

src/extension/alterschema/linter/dangling_additional_items.h

jviotti · 2025-07-03T18:29:48Z

src/extension/alterschema/linter/dangling_additional_items.h

+               {"https://json-schema.org/draft/2019-09/vocab/applicator",
+                "http://json-schema.org/draft-07/schema#",
+                "http://json-schema.org/draft-06/schema#",
+                "http://json-schema.org/draft-04/schema#"}) &&


I believe this rule applies to Draft 3 as well. Can you confirm on the spec?

Yes it does, adding tests for it as well

jviotti · 2025-07-03T18:30:02Z

test/alterschema/alterschema_lint_2019_09_test.cc

@@ -1661,8 +1661,7 @@ TEST(AlterSchema_lint_2019_09, unnecessary_allof_ref_wrapper_5) {
  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
    "$schema": "https://json-schema.org/draft/2019-09/schema",
    "allOf": [
-      { 
-        "type": "integer",
+      { "type": "integer",


Unintended change?

jviotti · 2025-07-03T18:31:02Z

I left a few comments. On testing:

Can you test cases where items is set to boolean schemas?
Can you test cases where items is set to an array and therefore confirm that additionalItems is NOT removed?
Can you test what happens if there is a $ref to additionalItems but then additionalItems gets removed?
- What we can do here is tweak the condition of the existing rule to only match instances of additionalItems that are not referenced by anything (using SchemaFrame in the condition, which has a references() method to introspect on the schema references). And then we probably need another non-auto fixable rule that catches the additionalItems that must be removed but have references to them

Karan-Palan · 2025-07-06T19:30:06Z

Renamed the rule, class, file, and all references.
Updated CMakeLists.txt
Added Draft 3 support with tests.
Added comprehensive tests for boolean items, array items, object items, and scenarios where the rule should not apply.

@jviotti , the PR is ready for review

jviotti · 2025-07-07T14:42:12Z

src/extension/alterschema/linter/additional_items_with_schema_items.h

+                "http://json-schema.org/draft-04/schema#",
+                "http://json-schema.org/draft-03/schema#"}) &&
+           schema.is_object() && schema.defines("items") &&
+           schema.defines("additionalItems") && schema.at("items").is_object();


The is_object check for items is still wrong, as the items keyword can be set to a boolean. Remember that in JSON Schema, a schema is either an object or a boolean. We have an is_schema function for this case

Also I think you are missing test cases covering that case: items set to a boolean

jviotti · 2025-07-07T14:42:24Z

src/extension/alterschema/linter/additional_items_with_schema_items.h

+                "http://json-schema.org/draft-04/schema#",
+                "http://json-schema.org/draft-03/schema#"}) &&
+           schema.is_object() && schema.defines("items") &&
+           schema.defines("additionalItems") && schema.at("items").is_object();


Suggested change

schema.defines("additionalItems") && schema.at("items").is_object();

schema.defines("additionalItems") && is_schema(schema.at("items"));

…undo unintended change Signed-off-by: karan-palan <karanpalan007@gmail.com>

Signed-off-by: karan-palan <karanpalan007@gmail.com>

Karan-Palan · 2025-07-08T19:12:30Z

@jviotti

I guess I understood, this is how the rule works now:

When items is a schema object: additionalItems is removed (because it's ignored)
When items is a boolean schema: additionalItems is removed (because it's ignored)
When items is an array: additionalItems is preserved (because the rule doesn't apply)

jviotti · 2025-07-08T21:53:41Z

That explanation makes sense!

…ng-additional-items

Signed-off-by: karan-palan <karanpalan007@gmail.com>

…ng-additional-items

Karan-Palan · 2025-07-13T13:17:57Z

@jviotti , resolved merge conflicts. Any comments?
@Relequestual, any other tests that come into your mind?

feat(alterschema): [linter] create rule to remove additional items wh…

767c38f

…en items is an objects Signed-off-by: karan-palan <karanpalan007@gmail.com>

Karan-Palan marked this pull request as ready for review July 3, 2025 09:18

jviotti reviewed Jul 3, 2025

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Update linter: add tests for draft 3, rename rule, update tests, and …

bb30244

…undo unintended change Signed-off-by: karan-palan <karanpalan007@gmail.com>

Karan-Palan force-pushed the linter/dangling-additional-items branch from 7c994f5 to bb30244 Compare July 8, 2025 18:13

fix(alterschema): [linter] add missing boolean test cases for all drafts

f600c3b

Signed-off-by: karan-palan <karanpalan007@gmail.com>

Karan-Palan added 3 commits July 9, 2025 04:11

Merge branch 'main' of github.com:Karan-Palan/core into linter/dangli…

e692ce3

…ng-additional-items

chore: [linter]undo unintended change

4407107

Signed-off-by: karan-palan <karanpalan007@gmail.com>

Merge branch 'main' of github.com:Karan-Palan/core into linter/dangli…

1cdd055

…ng-additional-items

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Linter: create rule to remove additional items when items is an object #1805

Linter: create rule to remove additional items when items is an object #1805

Karan-Palan commented Jul 2, 2025

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Karan-Palan commented Jul 8, 2025 •

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Karan-Palan commented Jul 13, 2025

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	schema.defines("additionalItems") && schema.at("items").is_object();
	schema.defines("additionalItems") && is_schema(schema.at("items"));

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Linter: create rule to remove additional items when items is an object #1805

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Linter: create rule to remove additional items when items is an object #1805

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Karan-Palan commented Jul 2, 2025

Implementation

Test Cases

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