Clarify spec about schemas with multiple types #458
Description
In #1401 of swagger-core, @webron mentioned that specifying multiple types for a schema is not valid.
The 2.0 Spec says for a schema object:
The following properties are taken directly from the JSON Schema definition and follow the same specifications:
[...]
- type
JSON Schema validation says in section 5.5.2:
5.5.2. type
5.5.2.1. Valid values
The value of this keyword MUST be either a string or an array. If it is an array, elements of the array MUST be strings and MUST be unique.
String values MUST be one of the seven primitive types defined by the core specification.
5.5.2.2. Conditions for successful validation
An instance matches successfully if its primitive type is one of the types defined by keyword. Recall: "number" includes "integer".
I would interpret this as my type: ["integer", "string"] property being valid JSON Schema, and thus also valid Swagger.
While the "null" type name is not available in swagger due to it missing in the list of available types, the same consideration applies to something like "type": ["integer", "string"]. If this is not supposed to be valid, the sentence quoted above needs to be changed.
(Also, instead of referring to the "latest" version of JSON schema, I would explicitly name the version used, so the validity of Swagger documents doesn't suddenly change whenever there is a new version of JSON schema.)