How to use references in JustinRainbow JsonValidator

Question

Can someone tell me how to make the JustinRainbow Json schema validator be able to find references.

This is the schema of foobar I'm trying to validate:

{
  "title": "foobar schema",
  "type": "object",
  "properties": {
    "pagination": {
       "$ref": "#/definitions/pagination"
    }
  },
  "required": ["pagination"]
}

And the definition of the pagination schema is contained in a separate file on my computer.

Trying to validate that without telling the JSON validator how to resolve references like this:

$uriRetriever = new JsonSchema\Uri\UriRetriever();
$refResolver = new JsonSchema\RefResolver($uriRetriever, $uriResolver);
$schema = $refResolver->resolve("file://".realpath(__DIR__."/foobar.json"));

Gives an error message:

File: file://features/foobar.json is found, but could not resolve fragment: #/definitions/pagination (JsonSchema\Exception\UnresolvableJsonPointerException)

Which is fair enough as there is no way for the validator to know how to find the file that contains the pagination schema definition....so how can I tell the RefResolver how to find the definition of the pagination schema?

I would prefer to be able to resolve the file through the local filesystem, rather than having to use URL's on a webserver.

Answer 1

The kind of reference used in your schema is a json pointer referring to another part of your schema file. You need to specify definition/pagination properties to get rid of the error.

{
  "title": "foobar schema",
  "type": "object",
  "properties": {
    "pagination": {
       "$ref": "#/definitions/pagination"
    }
  },
  "required": ["pagination"],
  "definitions": {
        "pagination": {
       
        }
    }
}

In order to refer to a definition in an other file you can write something like:

"pagination": {
  "$ref": "pagination.schema.json#"
}

Or even specify a particular node in the external file:

"pagination": {
  "$ref": "external_definitions.schema.json#/definitions/pagination"
}

The external_definitions.schema.json / pagination.schema.json should be looked for in the same folder as your schema containing the reference. The library should also provide some api to configure this lookup.

In my project I use JustinRainbow JsonValidator for php. It does not allow to provide a custom resolver, but the location where the referred files are search for can be influenced by "id" value in the schema.

Example, schema in main.schema.json:

{
  "id": "http://myweb.com/schemas/main.schema.json#",
  "title": "foobar schema",
  "type": "object",
  "properties": {
    "pagination": {
       "$ref": "pagination.schema.json#"
    }
  },
  "required": ["pagination"]
}

when validating this schema, so the validator tries to load the pagination.schema.json using:

php_get_contents('http://myweb.com/schemas/pagination.schema.json');