How should be specified a query/header parameter thats allow duplication

[joolfe]

As long as I understand in HTTP is possible to send duplicated query and header parameters, how the server handle this is out of the scope of the specification but I have observed that the combination of "name" and location (expressed by field "in") in parameters in Open API should be unique so what is the correct way to specify that an API allow multiple query/headers, for example:

HTTP://myapi.com?id=123&id=345

Best regards

[flaksp]

"4.8.12.3 Style Values" section covers how parameters may be represented with different data types (also check out table with examples in "4.8.12.4 Style Examples" section below). It is possible to represent array of query-parameters as you wish with style: form, explode: true and using schema of type array in schema keyword.

Example:

name: color
in: query
style: form
explode: true
schema:
  type: array
  uniqueItems: true
  items:
    enum: [blue, black, brown]

color=blue&color=black&color=brown

However, OpenAPI specification does not cover multiple headers with same name, so behaviour is undefined 😔 But it's nice idea to visit "Big thoughts for 4.0" discussion where we gather ideas for the next major update of the spec and suggest yours about headers with attached references to HTTP spec, existing issues and discussions if they exist.

[karenetheridge]

Multiple headers are supported too -- it would be style: simple, explode: false with type: array. See the examples at https://swagger.io/docs/specification/serialization/.

[handrews]

Looks like this was resolved, closing.