Recursive schema evaluation - stop evaluating initial value for empty array

[Monteth]

Uniforms go through the schema to get starting values for the following fields. Therefore, during the initial load, it must go through all the 'leaves' of the schema tree. This eager approach prevents us from processing recursive schemas. However, this doesn't have to be the case.

When we think about different types of recursive schemas, they only make sense when they can be completed in a finite amount of time. This requires specific points where the evaluation can stop. An array has a built-in mechanism for this. It can contain one or multiple values to continue expanding the tree, or it can have 0 elements to close off a branch. This enables us to evaluate a recursive schema and create a finite model. In this model, the 'leaves' can consist of empty arrays.

Consider this schema, where we can add multiple children on different levels, and it will only evaluate the next tree level when we add a new value to the model (+ button).
So the schema of the family tree is potentially infinite, but the model is finite.

{
  "type": "object",
  "properties": {
    "name": { "type": "string" },
    "children": {
      "type": "array",
      "items": { "$ref": "#" }
    }
  }
}

const model = {
  "children": [
    {
      "name": "Emma",
      "children": [
        {
          "name": "Olivia"
        },
        {
          "name": "Sophia",
          "children": [
            {
              "name": "Zoe"
            }
          ]
        }
      ]
    }
  ],
  "name": "Alice"
};

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.46%. Comparing base (ba4c593) to head (5878bf3).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1282      +/-   ##
==========================================
- Coverage   95.53%   95.46%   -0.07%     
==========================================
  Files         175      175              
  Lines        2867     2868       +1     
  Branches      773      773              
==========================================
- Hits         2739     2738       -1     
- Misses         59       61       +2     
  Partials       69       69              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[kestarumper]

We talked internally with @Monteth, and we also want to include a basic cycle detection mechanism to prevent freezing the browser tab (prevent infinite loops). Here's the proof of concept https://runkit.com/monteth/json-schema-cycles-detector.

[Monteth]

We talked internally with @Monteth, and we also want to include a basic cycle detection mechanism to prevent freezing the browser tab (prevent infinite loops).

I've tried to implement that, but since it is a little more complicated than we would like, I want to merge this PR without this check and (eventually) implement it under a dedicated issue.

I'd also reconsider if we really need that because I've spotted only one issue related to JSONSchema infinite loop (#596) that was fixed. This PR fixes one more case where it could take place so that it will be even less helpful but still will have an impact on the package footprint and render performance.

@kestarumper

[piotrpospiech]

I think you have some leftovers from trying to implement loops detection.

[piotrpospiech]

Why two different versions? It is dev depenendency, not a peer dependency. Why is this needed? Where is this used?

[piotrpospiech]

Why is it added here? It was already added to the json bridge package.

[piotrpospiech]

Is this used?

[piotrpospiech]

Where did you use it?

[Monteth]

I think you have some leftovers from trying to implement loop detection.

Yes, indeed. Sorry for that!