Unable to use "$ref" with "$id" and "jar" protocol

I am trying to refer a separate json schema file using $ref but getting Malformed url exception without adding file:// before the file name. After adding file:// , the code expects BaseJsonSchema.json in the current directory instead of data/src/main/resources

Schema File: data/src/main/resources/TwitterJsonSchema.json

{
  "description" : "Twitter data",
  "type":"object",
  "allOf":[
     { "$ref":"BaseJsonSchema.json#/definitions/baseData" },
    {
         "properties": {
             "followersCount": {"type":"number" },
          }
     }]
} 

Schema File: data/src/main/resources/BaseJsonSchema.json

{
    "title": "baseData",
   "type":"object",
   "definitions":{
     "baseData": {
          "type": "object",
          "properties": {
                  "sourceUrl": {
                        "type": "string"
                   },
          }
      }
   }
}

Code:

package com.data.commons.validator 

class JsonValidator{

    public static void main(String[] args) {
        validateJsonSchema(args[0], args[1])
    }

    static void validateJsonSchema(String jsonSchemaFile, String json) {
        JSONObject jsonObject = new JSONObject(json)
        Schema schema = SchemaLoader.builder().schemaJson(new JSONObject(new JSONTokener(this.getClass().getResourceAsStream(jsonSchemaFile)))).build().load().build()
        schema.validate(jsonObject)
    }
}

Exception:

Exception in thread "main" java.io.UncheckedIOException: java.net.MalformedURLException: no protocol: BaseJsonSchema.json
	at org.everit.json.schema.loader.internal.DefaultSchemaClient.get(DefaultSchemaClient.java:35)
	at org.everit.json.schema.loader.internal.JSONPointer.executeWith(JSONPointer.java:87)
	at org.everit.json.schema.loader.internal.JSONPointer.lambda$forURL$1(JSONPointer.java:141)
	at org.everit.json.schema.loader.internal.JSONPointer.query(JSONPointer.java:162)
	at org.everit.json.schema.loader.SchemaLoader.lookupReference(SchemaLoader.java:578)
	at org.everit.json.schema.loader.SchemaLoader.buildSchemaWithoutExplicitType(SchemaLoader.java:435)
	at org.everit.json.schema.loader.SchemaLoader.load(SchemaLoader.java:517)
	at org.everit.json.schema.loader.SchemaLoader.loadChild(SchemaLoader.java:530)
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
	at java.util.stream.IntPipeline$4$1.accept(IntPipeline.java:250)
	at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:110)
	at java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:693)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
	at org.everit.json.schema.loader.SchemaLoader.tryCombinedSchema(SchemaLoader.java:640)
	at org.everit.json.schema.loader.SchemaLoader.load(SchemaLoader.java:514)
	at org.everit.json.schema.loader.SchemaLoader$load$0.call(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:117)
	at com.tracxn.data.commons.validator.JsonValidator.validateJsonSchema(JsonValidator.groovy:19)
	at com.tracxn.data.commons.validator.JsonValidator.main(JsonValidator.groovy:11)
Caused by: java.net.MalformedURLException: no protocol: BaseJsonSchema.json
	at java.net.URL.<init>(URL.java:593)
	at java.net.URL.<init>(URL.java:490)
	at java.net.URL.<init>(URL.java:439)
	at org.everit.json.schema.loader.internal.DefaultSchemaClient.get(DefaultSchemaClient.java:33)
	... 24 more

[ankshah]

the base is jar://data/target/data-1.0.0.jar!/TwitterJsonSchema.json , then URI.resolve() returns jar://data/target/data-1.0.0.jar!/BaseJsonSchema.json , which is correct, but you get a MalformedURLException one step later when you try to open the connection.

Okay. Will try to debug this oddity later. Thanks for the pointer.

I am not using spring. I have worked the issue out by modifying the json schema file at runtime. My base $refs are limited to one or two files, I read the definitions from these files and inject in other schemas at runtime - a bit hackish, but works for my use case.

Thanks for your time and support @erosb 👍

[erosb]

I’m not sure what version of json schema are you trying to use, but "id" works only for draft-4 schemas (which is an old version), and the keyword changed to "$id" in draft-6.

Also, the value you set "jar:file:data/target/data-1.0.0.jar!/TwitterJsonSchema.json" is not a valid URL so it definitely won’t work.

There are multiple ways to make progress on it:

• the library just uses the URL class of the JDK so the library supports whatever protocol supported by the URL class. If necessary, you can define your own protocol handler.
• alternatively you can use a custom SchemaClient interface and wire it into the SchemaLoader. This part will look something like this:

SchemaLoader loader = SchemaLoader.builder().schemaJson(yourSchemaJson).httpClient(new YourSchemaClient()).build();
Schema schema = loader.load().build();

Then in the YourSchemaClient you load the schema from whatever source you would like to. You will be given a String as parameter and should return the InputStream of the found json content.