"Could not resolve the metaschema of the schema" error although the meta schema is accessible

[loiclefevre]

Hi, I've an issue related to local development.
I have 2 local HTTP endpoints that provides me a vocabulary and a meta schema.

When I want to validate it, it says:

Could not resolve the metaschema of the schema
Error in C:\dev\projects\apidays-paris-2025\json_schema.json
Rule ID:
cli-error-with-id
Schema:
http://localhost/ords/developer/meta/database-meta.json

I can access http://localhost/ords/developer/meta/database-meta.json though without any problem:

Am I missing something?

Thanks

[loiclefevre]

I'm using version 0.0.5

[jviotti]

Can you paste the contents of that schema you have in localhost?

[loiclefevre]

Changed a bit the directory structure:

• JSON Schema vocabulary: http://localhost/vocab/database.json

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "http://localhost/vocab/database.json",
  "properties": {
    "dbObject": {
      "type": "string"
    }
  }
}

• JSON Schema meta schema: http://localhost/meta/database-meta.json

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "http://localhost/meta/database-meta.json",
  "$vocabulary": {
    "https://json-schema.org/draft/2020-12/vocab/core": true,
    "https://json-schema.org/draft/2020-12/vocab/applicator": true,
    "https://json-schema.org/draft/2020-12/vocab/validation": true,
    "http://localhost/vocab/database.json": true
  },
  "$defs": {
    "meta": {
      "$dynamicAnchor": "meta",
      "allOf": [
      {
        "$ref": "https://json-schema.org/draft/2020-12/meta/core"
      },
      {
        "$ref": "https://json-schema.org/draft/2020-12/meta/applicator"
      },
      {
        "$ref": "https://json-schema.org/draft/2020-12/meta/validation"
      },
      {
        "$ref": "http://localhost/vocab/database.json"
      }
     ]    
    }
  }
}

• JSON Schema using the meta schema (local file):

{
  "$schema": "http://localhost/meta/database-meta.json",
  "$id": "https://free/freepdb1/developer/emp/1.0.2",
  "title": "EMP",
  "description": "Employee Name",
  "x-version": "1.0.2",
  "type": "object",
  "required": [ "EMPNO" ],
  "properties": {
    "EMPNO": {
      "type": "number",
      "extendedType": "number"
    },
    "ENAME": {
      "oneOf": [
        {
          "type": "null",
          "extendedType": "null"
        },
        {
          "type": "string",
          "maxLength": 10,
          "extendedType": "string"
        }
      ]
    },
    "JOB": {
      "oneOf": [
        {
          "type": "null",
          "extendedType": "null"
        },
        {
          "type": "string",
          "maxLength": 9,
          "extendedType": "string"
        }
      ]
    },
    "MGR": {
      "oneOf": [
        {
          "type": "null",
          "extendedType": "null"
        },
        {
          "type": "number",
          "extendedType": "number"
        }
      ]
    },
    "HIREDATE": {
      "oneOf": [
        {
          "type": "null",
          "extendedType": "null"
        },
        {
          "type": "string",
          "extendedType": "date"
        }
      ]
    },
    "SAL": {
      "oneOf": [
        {
          "type": "null",
          "extendedType": "null"
        },
        {
          "type": "number",
          "extendedType": "number",
          "sqlPrecision": 7,
          "sqlScale": 2
        }
      ]
    },
    "COMM": {
      "oneOf": [
        {
          "type": "null",
          "extendedType": "null"
        },
        {
          "type": "number",
          "extendedType": "number",
          "sqlPrecision": 7,
          "sqlScale": 2
        }
      ]
    },
    "DEPTNO": {
      "oneOf": [
        {
          "type": "null",
          "extendedType": "null"
        },
        {
          "type": "number",
          "extendedType": "number"
        }
      ]
    }
  },
  "dbObject": "DEVELOPER.EMP",
  "dbObjectType": "view"
}

[loiclefevre]

[jviotti]

Hey @loiclefevre , sorry for the late reply. I think this notification got lost in the noise 🙏🏻

I think the problem here is that the $schema keyword is, of course, an absolute URI. And because that URI is not a file URI (and it shouldn't in this case!), the tool cannot really know where to find it. i.e. the tool won't attempt to automatically analyse all the schemas in the current directory to see if there is a schema matching that identifier (and it probably shouldn't?)

This is why we introduced the jsonschema.json file I presented a bit before. I think something like this would make it work:

{
  "resolve": {
    "http://localhost/meta/database-meta.json": "./path/to/database-meta.json"
  }
}

Then when either the CLI or the VS Code extension loads the schema, it figures out from jsonschema.json on the same folder where to go find the schema with identifier "http://localhost/meta/database-meta.json". You might also need to register http://localhost/vocab/database.json in the same way for the meta => vocab reference to also work.

[jviotti]

Seeing what you are actually trying to do here, and I think it has some overlap with https://github.com/sourcemeta/extensions/blob/main/schemas/extension/database/v1.json, where I'm actually trying to come with a JSON Schema extensions registry having meta-schemas for all of these custom vocabularies.

Hopefully we get to properly standardise that soon

[loiclefevre]

Hey @loiclefevre , sorry for the late reply. I think this notification got lost in the noise 🙏🏻

I think the problem here is that the $schema keyword is, of course, an absolute URI. And because that URI is not a file URI (and it shouldn't in this case!), the tool cannot really know where to find it. i.e. the tool won't attempt to automatically analyse all the schemas in the current directory to see if there is a schema matching that identifier (and it probably shouldn't?)

This is why we introduced the jsonschema.json file I presented a bit before. I think something like this would make it work:

{
"resolve": {
"http://localhost/meta/database-meta.json": "./path/to/database-meta.json"
}
}
Then when either the CLI or the VS Code extension loads the schema, it figures out from jsonschema.json on the same folder where to go find the schema with identifier "http://localhost/meta/database-meta.json". You might also need to register http://localhost/vocab/database.json in the same way for the meta => vocab reference to also work.

Well in fact, the JSON meta schema is accessible directly with the URL provided. It's not a file on the filesystem, but it can rather be downloaded directly from HTTP request.

Note I'm saying HTTP here, not HTTPS.

[jviotti]

Hmm, nothing immediate comes to mind. Two things to try:

• In the Visual Studio Code extension, on the metaschema tab, there is a "raw output" accordion. Can you paste that? i.e. it is passing --http to the CLI?
• How are you hosting the file on http://localhost? Is there a way I could reproduce the exact same setup? The only thing I can think of is that we somehow confuse the cURL code? Though plain HTTP should definitely work. If I could reproduce, I could probably dig deeper
• Does it work if you run it on the CLI: jsonschema metaschema json_schema.json --http --verbose? Just to rule out anything odd with the extension

[loiclefevre]

Hmm, nothing immediate comes to mind. Two things to try:

• In the Visual Studio Code extension, on the metaschema tab, there is a "raw output" accordion. Can you paste that? i.e. it is passing --http to the CLI?

Here is the screenshot:

I indeed suspect it is not passing the --http cli parameter. See point #3 below, CLI with --http works, and when I remove the --http, I get the same error message as above 👆

• How are you hosting the file on http://localhost? Is there a way I could reproduce the exact same setup? The only thing I can think of is that we somehow confuse the cURL code? Though plain HTTP should definitely work. If I could reproduce, I could probably dig deeper

I'm hosting it using Oracle REST Data Services. You can find the full setup here: https://github.com/loiclefevre/api-days-2025/blob/main/README.md#setup

• Does it work if you run it on the CLI: jsonschema metaschema json_schema.json --http --verbose? Just to rule out anything odd with the extension

Yes, it works on the CLI!

\.vscode\extensions\sourcemeta.sourcemeta-studio-0.0.5\node_modules\@sourcemeta\jsonschema\jsonschema-windows-x86_64 metaschema json_schema.json --http --verbose
Resolving over HTTP: http://localhost/meta/database-meta.json
Resolving over HTTP: http://localhost/vocab/database.json
ok: json_schema.json
  matches http://localhost/meta/database-meta.json

[loiclefevre]

Got it, the lint command doesn't manage any --http cli parameter!

See: https://github.com/sourcemeta/studio/blob/main/vscode/src/commands/CommandExecutor.ts#L71

[jviotti]

Oh good catch. Fixing it now. I'll publish a new version in a bit