Using ref in JSON Schema to refer to a local schema on disk

Question

I have a JSON schema file:

{  
   "id":"http://schema.acme.com/user",
   "$schema":"http://json-schema.org/draft-06/schema#",
   "definitions":{  
      "user":{  
         "description":"The name the user has selected",
         "type":"object",
         "required":[  
            "username",
            "premium"
         ],
         "properties":{  
            "username":{  
               "type":"string",
               "maxLength":10,
               "minLength":1
            },
            "premium":{  
               "type":"boolean"
            }
         }
      }
   }
}

and I want to validate this against a json object. So I create a temporary object of that type with this schema:

{  
   "id":"http://schema.acme.com/uName",
   "$schema":"http://json-schema.org/draft-06/schema#",
   "properties":{  
      "uName":{  
         "$ref":"smUserSchema.json#/definitions/user"
      }
   },
   "required":[  
      "uName"
   ]
}

and I have this JSON data file:

{  
   "uName":{  
      "username":"Bob",
      "premium":true
   }
}

The goal here is to not embed my temporary object in my JSON schema for the class type. (And yes, one of my problems here is that I'm trying to for OO techniques onto JSON. That's true, I'm just doing this for re-use and inheritance reasons, there might be a better way.)

When I go to validate this I get this error:

$ ajv -s uNameSchema.json -d validUser.json 
schema uNameSchema.json is invalid
error: can't resolve reference smUserSchema.json#/definitions/user from id http://schema.acme.com/uName#

How can I include on JSON schema in another schema?

See Also:

score 2 · Answer 1 · answered Nov 23 '17 at 19:35

2

You need to make sure ajv is aware of smUserSchema.json, it won't find it automatically. There's a command line option to pass dependent schemas but I can't recall it offhand. ajv --help should tell you (I don't have it readily available).

answered Nov 23 '17 at 19:35

Henry Andrews

663
3
6

I thought the JSON Schema spec said that the referenced schemas would be searched for in the directory of the schema? Also, ajv doesn't seem to have a search path. I think you're thinking of the ajv library which does have that ability. (I think! LOL) – Paul Cezanne Nov 27 '17 at 14:16
I'm wrong about the above. "help" doesn't mention it but the web site does talk about the "-r - referenced schemas" options. – Paul Cezanne Nov 27 '17 at 15:08
1

Hmmm, doesn't work and it was so promising! // $ ajv -s uNameSchema.json -d validUser.json -r usernameSchema.json // schema uNameSchema.json is invalid // error: can't resolve reference smUserSchema.json#/definitions/user from id http://schema.acme.com/uName# – Paul Cezanne Nov 27 '17 at 15:45
1

This is definitely an implementation usage issue, so I'd recommend asking over at the ajv or ajv-cli repos, or tagging this question with ajv as I know the ajv developer answers questions here. – Henry Andrews Nov 27 '17 at 22:28

score 0 · Answer 2 · answered Sep 15 '21 at 09:24

You've set the $id of the schema you want to reference to http://schema.acme.com/user.

However, you use a relative refernece of smUserSchema.json#/definitions/user, which resolves to http://schema.acme.com/smUserSchema.json#/definitions/user.

You need to change either the $id defined in your referenced schema, or the relative URI used for $ref, so that they match.

I realise this answer is a little late, and I hope you resolved your issue before now, but it may still be useful for others.

Using ref in JSON Schema to refer to a local schema on disk

2 Answers2