Best practice for reusing validation?

[emsearcy]

Hello!

I have multiple payloads that I am designing to share the same standard pagination schema, and I assumed it would be best to reuse a common definition of the Enum, rather than duplicate them inline in each payload. Since Enum is a validation, not a type, it's not immediately obvious to me how to do this best.

I've come up with the following ideas:

Define as a slice of any values:

var SortValues = []any{"name_asc", "name_desc", "created_asc", "created_desc"}

// ...
Method("search", func() {
  Payload(func() {
     Attribute("sort", String, "Sort order for results", func() {
        Enum(SortValues...)
        Default("name_asc")
      })
      Attribute("next_page", String, "Opaque token for next page")
      // ...
})

or, as a type "Sortable" that I can leverage via Extend() in my payload:

var Sortable = Type("Sortable", func() {
  Attribute("sort", String, "Sort order for results", func() {
    Enum("name_asc", "name_desc", "created_asc", "created_desc")
    Default("name_asc")
  })
  Attribute("page_token", String, "Opaque token for pagination")
})

// ...
Method("search", func() {
  Payload(func() {
    Extend(Sortable)
    // ...
})

The latter has the advantage that I can group multiple parameters related to pagination. The OpenAPI spec creates an extra object for the latter, but is otherwise unchanged with respect to the HTTP payload schema.

Any best practices or recommendations from others on reusing a set of Enum allowed values?

[raphael]

These two approaches are both valid depending on your cases. An approach that I've been using too is defining the enum type explicitly:

var SortOrder = Type("SortOrder", String, func() {
    Enum(types.NameAsc, types.NameDesc, types.CreatedAsc, types.CreatedDesc)
})

where types is a package imported both by the design and the implementation.