undefined rootSchema in resolveSchema() causes: Cannot read properties of undefined (reading 'properties')

[mirismaili]

Describe the bug

In resolveSchema() function:

jsonforms/packages/core/src/util/resolvers.ts

Lines 156 to 162 in 81f1f19

	if (resultSchema !== undefined && resultSchema.$ref !== undefined) {
	try {
	return retrieveResolvableSchema(schema, resultSchema.$ref);
	} catch (e) {
	return retrieveResolvableSchema(rootSchema, resultSchema.$ref);
	}
	}

rootSchema in catch block can be undefined. This is an optional parameter of resolveShcema():

jsonforms/packages/core/src/util/resolvers.ts

Lines 110 to 114 in 81f1f19

	export const resolveSchema = (
	schema: JsonSchema,
	schemaPath: string,
	rootSchema?: JsonSchema
	): JsonSchema => {

and its value hasn't been checked (for being undefined) before.

---

This is not only a potential bug. The function has actually been called without rootSchema in some places (e.g. in testers.js) and I especially encountered it after this:

jsonforms/packages/core/src/testers/testers.ts

Line 89 in 81f1f19

currentDataSchema = resolveSchema(schema, schemaPath);

Expected behavior

Obviously, having no error.

But I think the more important issue here is why schema $refs should be resolved in testers many times? This would be a big performance issue! The schema can be parsed (resolved) one time and be used multiple times (in testers and probably any other places).

Steps to reproduce the issue

1. Go to Playground
2. Set:
   JSON-Schema:

   {
     "type": "object",
     "definitions": {
       "test": {
         "type": "string"
       }
     },
     "properties": {
       "foo": {
         "type": "object",
         "properties": {
           "bar": {
             "$ref": "#/definitions/test"
           }
         }
       }
     }
   }

   UI-Schema:

   false

   Data:

   {}

Screenshots

Note: The above playground works with JsonForms v3.0.0-alpha.2

In which browser are you experiencing the issue?

Google Chrome v96.0.4664.93 (Official Build) (64-bit)

[sdirix]

Hi @mirismaili, thanks for the report!

Yes the resolving is not in the best state at the moment in the alpha release. We will make sure that all basic resolving cases work before the stable release, see #1750 for more information.

Note that you can always resolve your JSON Schema yourself before handing it over to JSON Forms. I would like recommend json-refs for that, see https://jsonforms.io/docs/ref-resolving

[mirismaili]

Hi @sdirix, you're welcome.

OK. I did so. Thanks.

[sdirix]

This issue should be solved by #1829. Can you verify?

[sdirix]

I'll close this for now. Please reopen if you encounter further issues.