Support self-referential schemas ($ref: '#')

[brettz9]

What would it take to support $ref values pointing to #?

[jdorn]

Any support for recursive/circular/self-referential schemas would require a big rewrite of a lot of the core code.

I definitely want to add support for recursion, but I don't know if I'm ready for that big of an endeavor right now. Every time I've tried thinking through how I would implement it, I came up with a lot of subtle complications, mostly revolving around oneOf and validation.

[brettz9]

While this would surely not be enough for your time, would a donation of say $150 at least encourage or enable you to get to it sooner? This would be very important for a project I am working on, and I can imagine it would take me much longer to learn your code and struggle through it myself. Maybe other validators out there could provide some insights.

[jdorn]

I thought through the recursion problem a bit and I think I have a tentative list of changes needed. I'm sure other stuff will pop up as it's being implemented, but it's not as bad as I first thought. I can't make any promises about when I can get to this. I'll try to start a branch within the next week though.

• Validator recursively finds and loads all external $ref urls via ajax (same as now), but doesn't expand them right away.
• During validation, expand $refs when needed at each recursion level. Check for infinite recursion here.
• Before running resolver functions, expand top level $refs.
• Modify a few resolver functions to expand other $refs when needed.
• When initializing an editor, expand top level $refs. Check for infinite recursion here too.
• Change object editor to expand $refs in properties.
• Need a way to tell an object to not load particular non-required properties during initialization.
• The array and table editors currently create a dummy first item during initialization to determine the columns, editor width, etc.. This will have to be removed.
• The multiple editor for oneOf and compound types does some lazy loading, but it still always initialized the first option no matter what. This needs to change.

I'm going to use this as a test schema:

{
  "$ref": "#/definitions/person",
  "definitions": {
    "person": {
      "type": "object",
      "title": "Person",
      "properties": {
        "name": { "type": "string" },
        "friends": {
          "type": "array",
          "items": {
            "title": "Friend",
            "$ref": "#/definitions/person"
          }
        }
      }
    }
  }
}

[brettz9]

Let me know if and when you find time to actually get started (and where to contribute), and I will be happy to make a deposit.

[brettz9]

I haven't taken time to digest your approach fully, but does "During validation, expand $refs when needed at each recursion level" mean that one could have a system whereby a potentially infinite number of schemas were inter-linking without needing to grab them all ahead of time and merely avoid recursion? That would be very cool...

[brettz9]

And back to the JSON Ref idea, if, e.g., a table format widget selectively pulled in, e.g., 50 rows at a time, re-validation could be done lazily as data was pulled in imposing structure on the data without inevitably requiring all possible content to be pre-loaded (and in some use cases, that may even be impossible).