`anyOf` parameters always listed as `X | (X | Y)`

[multimeric]

Q&A (please complete the following information)

• OS: macOS
• Browser: FireFox
• Version: 140.5
• Method of installation: downloaded the pre-compiled bundle and used the dist/ directory
• Swagger-UI version: 5.30.3
• Swagger/OpenAPI version: 3.1.0

Content & configuration

Example Swagger/OpenAPI definition:

{
    "openapi": "3.1.0",
    "paths": {
        "/greet": {
            "get": {
                "parameters": [
                    {
                        "name": "name",
                        "schema": {
                            "anyOf": [
                                {
                                    "type": "string"
                                },
                                {
                                    "type": "integer"
                                }
                            ]
                        }
                    }
                ]
            }
        }
    }
}

Swagger-UI configuration options:
Not changed from defaults

Describe the bug you're encountering

To reproduce...

Steps to reproduce the behavior:

1. Create an OpenAPI spec that uses anyOf for a parameter
2. Look at the generated docs for that parameter

Expected behavior

In the above example, I expect to see string | integer

Screenshots

Additional context or thoughts

[elefores]

I'm having the same issue. I quickly looked at the source code and found the composeJsonSchema function in src/core/components/parameter-row.jsx. This is what it does:

composeJsonSchema(schema) {
  const { fn } = this.props
  const oneOf = schema.get("oneOf")?.get(0)?.toJS()
  const anyOf = schema.get("anyOf")?.get(0)?.toJS()
  return fromJS(fn.mergeJsonSchema(schema.toJS(), oneOf ?? anyOf ?? {}))
  //                                  ↑ target        ↑ source
}

mergeJsonSchema destructures both parameters and merges them:

const merged = { ...source, ...target }

N.B. mergeJsonSchema function is the merge function but it is renamed when exported from the fn module.

So, with your example @multimeric, it takes the first element of the anyOf array ({ "type": "string" }) and merges it into the parent schema. The final schema becomes:

{
  "openapi": "3.1.0",
  "paths": {
    "https://github.com/greet": {
      "get": {
        "parameters": [
          {
            "name": "name",
            "schema": {
              "type": "string", // comes from the first element of anyOf
              "anyOf": [
                { "type": "string" },
                { "type": "integer" }
              ]
            }
          }
        ]
      }
    }
  }
}

Then the makeGetType function, which displays the type in the UI, reads the type value (l.128) and concatenates it with all elements in the anyOf array (l.158). That’s why we end up with string | (string | integer). If we generalize to any types, this results in X | (X | Y).

I don’t know why we try to concatenate all these values. It seems counterintuitive to define both type and anyOf at the same level, but I don’t know enough about OpenAPI to say whether this is spec-compliant.

Looking at git blame, I see that @glowcloud implemented composeJsonSchema. Maybe they know the reason behind it.

Cheers.