question: optional fields

[will-moore]

Hi, I'm wondering if it's possible to mark a field as optional in the schema?

I was expecting something like:

fields:
  - name: foo
    type: string
    required: false

or

fields:
    foo?: string

The first is invalid and the second fails validation if foo field isn't found.

Is there some other way to achieve this, or is the scope of validation limited to required fields only?

Many thanks,
Will.

[tom-tan]

You can use null type for this purpose.
For example:

fields:
  - name: foo
    type: [string, "null"]

or

fields:
  - name: foo
    type: string?

Notes:

• [string, "null"] represents a union type. It comes from Avro Schema.
• Schema Salad considers a field with "null" type as optional.

[will-moore]

That's great, thanks.
I had actually tried something like [string, "null"] as a list in yaml but not with the correct syntax.