requestBody.content.multipart/form-data.schema.properties.<file>.contentEncoding (and contentMediaType) is not valid OS3.0

[NPellet]

Those two fields (contentEncoding and contentMediaType) are not in the OS 3.0 spec, though they are in the OS 3.1 spec.

Our generator only supports 3.0, so it fails there. I will investigate what a fix would take.

[NPellet]

Content encoding is added here
https://github.com/danielgtaylor/huma/blob/main/formdata.go#L241

[NPellet]

contentMediaType is added here

huma/schema.go

Line 168 in c7a8a79

var contentMediaType string

[NPellet]

I see there's downgrade code already

huma/openapi.go

Lines 1624 to 1639 in c7a8a79

	// Base64 / binary uploads
	if k == "application/octet-stream" {
	if ct, ok := v.(map[string]any); ok && len(ct) == 0 {
	m[k] = map[string]any{
	"schema": map[string]any{
	"type": "string",
	"format": "binary",
	},
	}
	}
	}
	if k == "contentEncoding" && v == "base64" {
	delete(m, k)
	m["format"] = "base64"
	continue

[NPellet]

Here's our schema

      requestBody:
        content:
          multipart/form-data:
            encoding:
              Data:
                contentType: text/plain
              file:
                contentType: text/plain
            schema:
              properties:
                Data:
                  $ref: "#/components/schemas/CertificateImportData"
                file:
                  contentEncoding: binary
                  contentMediaType: application/octet-stream
                  format: binary
                  type: string
              required:
                - file
              type: object

[NPellet]

Ok this is indeed not 3.0.3 valid, and it's under the SchemaObject specification:

https://spec.openapis.org/oas/v3.0.3#schema-object

In general (not just for requestBody or for multipart encoding), those 2 properties are not allowed in OS 3.0.3

[NPellet]

I would propose something like #919