Questions regarding `QueryByExample` structure and handling

[Joshua Coffey]

Hello,

I have some questions regarding the proper handling of QueryByExample objects.

I understand that many of these questions may not yet have answers, but I'd appreciate any insight that can be provided.

1. Are the @context and type fields required or optional?
2. What is the datatype of these fields?
   • I am operating under the assumption that they are both string | string[] -- is this fair?
3. How are the @context and type fields to be handled?
   • I am operating under the assumption that every value in the example @context array (whether it be expressed as an array of strings or a string itself) must be present in the credential's @context array, but additional values may be present in the credential's @context array. Is this fair?
   • I am operating under an equal assumption for the type field.
4. Is credentialSubject limited to only id and name fields, or is it intended for arbitrary key/values to query against the credential's credentialSubject?
   • My intuition tells me that any key/value pairs are valid, but the comment above it in Example 2 states You can request a specific subject id, which implies that that is the only intended usage.
5. Assuming credentialSubject is not limited to id and name, how is comparison meant to be handled?
   • Comparisons of primitives is intuitive, but stringy equality (does 5 match "5"?) should be clarified.
   • Comparisons of objects is also intuitive -- just recurse.
     • I am assuming, however, that all object comparisons (including the top-level example.credentialSubject to credential.credentialSubject comparison itself) are loose in the sense that the object on the credential may have additional fields not specified by the example object.
   • How should one perform a comparison of arrays?
     • See below

Array Comparison in credentialSubject

(This is all assuming that the credentialSubject field in the example query is not restricted to id and name fields)

Given the following query:

{
  "type": "QueryByExample",
  "credentialQuery": {
    "example": {
      "credentialSubject": {
        "primitive_array_one": [0, 1, 2],
        "primitive_array_two": [10, 11, 12],
        "complex_array": [
          {
            "a": 1
          },
          {
            "b": 2
          }
        ]
      }
    }
  }
}

And the following credentialSubject from a VerifiableCredential:

{
  "credentialSubject": {
    "id": "whatever",
    "primitive_array_one": [0, 1, 2, 3],
    "primitive_array_two": [12, 11, 10],
    "complex_array": [
      {
        "a": 1,
        "b": 2,
      },
      {
        "b": 3
      }
    ]
  }
}

It's not entirely clear how to handle this query by example.

• primitive_array_one
  • The credential's primitive_array_one contains all values of the example's primitive_array_one, in the same order and position, but it has additional entries.
• primitive_array_two
  • The credential's primitive_array_two contains all values of the example's primitive_array_two, and has no additional values, but they are not in the same order.
• complex_array
  • The example is looking for an object with an a value equal to 1, and an object with a b value equal to 2.
    • The credential does, in fact, have an object with an a value equal to 1, and an object with a b value equal to 2.
    • However, they're the same object, which likely isn't what the person who wrote the query was intending.