Partially completed array values with minItems get replaced by defaults

[RPiAwesomeness]

Prerequisites

• I have searched the existing issues
• I understand that providing a SSCCE example is tremendously useful to the maintainers.
• I have read the documentation
• Ideally, I'm providing a sample JSFiddle, Codesandbox.io or preferably a shared playground link demonstrating the issue.

What theme are you using?

core

Version

5.x

Current Behavior

If an array field has the minItems key set and has at least 1 less item than that, the values are replaced with the defaults. This only occurs when calling the computeDefaults function directly, such as in a test-case.

Expected Behavior

The existing form values are not replaced

Steps To Reproduce

1. Check out main
2. Add the following test to packages/utils/test/schema/getDefaultFormStateTest.ts:

it('should combine defaults with raw form data for a required array property with minItems', () => {
    const schema: RJSFSchema = {
      type: 'object',
      properties: {
        requiredArray: {
          type: 'array',
          items: { type: 'string', default: 'default0' },
          minItems: 2,
        },
      },
      required: ['requiredArray'],
    };
    expect(
      computeDefaults(
        testValidator,
        schema,
        {
          rootSchema: schema,
          rawFormData: { requiredArray: ['raw0'] },
          behaviorBitFlags: DefaultFormStateBehavior.IgnoreMinItemsUnlessRequired,
        }
      )
    ).toEqual({ requiredArray: ['raw0', 'default0'] });
  });
});

3. Confirm the test fails, with the returned value being { requiredArray: ['default0', 'default0'] }

Environment

- OS: Windows 11 (WSL 2)
- Node: v19.4.0
- npm: 9.3.0

Anything else?

This was encountered during work on an MR and was discussed with @heath-freenome. It seems like this doesn't actually affect the functionality of the form in a way I can replicate right now on the Playground, just when testing the computeDefaults function directly. Thus this is more of a placeholder/technical bug than one that is actively impacting the way the library works.

Potentially related to #2980

[RPiAwesomeness]

Similar test:

it('should return partial array for an optional array property with minItems when provided with a partial array', () => {
  const schema: RJSFSchema = {
    type: 'object',
    properties: {
      optionalArray: {
        type: 'array',
        minItems: 2,
      },
    },
  };
  expect(
    computeDefaults(testValidator, schema, {
      rootSchema: schema,
      rawFormData: { optionalArray: ['test'] },
      behaviorBitFlags: DefaultFormStateBehavior.IgnoreMinItemsUnlessRequired,
    })
  ).toEqual({ optionalArray: ['test'] });
});

Will fail with the returned value being {optionalArray: [undefined]} because there is not defined default value for the items.

[heath-freenome]

Fixed by #3604

[anthonycaron]

What should be the behavior for an optional array with no default value if we don't have a value for the array ?
rawFormData would have a value of {}.
Not sure if the expected result should be the same: {} or { optionalArray: undefined }. Or something else ?
I would go for { optionalArray: undefined } since it's declared in the schema hence I guess we expect to have in our resulting data but with a value of undefined since it's optional. Also ajv would consider the data as valid in that case.

Here's the test:

it('should return partial array for an optional array property with minItems when provided with a partial array', () => {
  const expectedResult = { optionalArray: undefined };
  const schema: RJSFSchema = {
    type: 'object',
    properties: {
      optionalArray: {
        type: 'array',
        minItems: 2,
        items: { type: 'string' },
      },
    },
  };
  expect(
    computeDefaults(testValidator, schema, {
      rootSchema: schema,
      rawFormData: {},
      behaviorBitFlags: DefaultFormStateBehavior.IgnoreMinItemsUnlessRequired,
    })
  ).toEqual(expectedResult);
});

[heath-freenome]

@anthonycaron it's debatable honestly. I'm leaning towards expanding the new experimental behavior to give more control over the individual states as best we can.

[anthonycaron]

@heath-freenome Oh I didn't know about this. Sounds good, thanks for your feedback!