Define array of multiple models in Swagger 2.0 - swagger

Question

This is my first foray into Swagger so please be gentle.
I have the following definitions:
definitions:
Payload:
type: object
properties:
indicators:
type: array
items:
$ref: '#/definitions/Indicator'
Indicator:
type: object
properties:
type:
type: string
computeOn:
type: array
items:
type: string
default:
- close
parameters:
type: object
BBANDS:
properties:
type:
type: string
default: BBANDS
computeOn:
type: array
items:
type: string
default:
- close
parameters:
type: object
properties:
timeperiod:
type: integer
format: int32
default: 5
nbdevup:
type: integer
format: int32
default: 2
nbdevdn:
type: integer
format: int32
default: 2
matype:
type: integer
format: int32
default: 0
DEMA:
properties:
type:
type: string
default: DEMA
computeOn:
type: array
items:
type: string
default:
- close
parameters:
type: object
properties:
timeperiod:
type: integer
format: int32
default: 5
So Payload has a property called indicator which is an array of Indicators. The BBANDS and DEMA are models which are of type Indicator (which I know doesn't translate to Swagger). What I'd like to do is define an array of the actual models with their defaults, in this case BBANDS and DEMA. Something like this:
definitions:
Payload:
type: object
properties:
indicators:
type: array
items:
- '#/definitions/BBANDS'
- '#/definitions/DEMA'
or
definitions:
Payload:
type: object
properties:
indicators:
type: array
items:
- $ref '#/definitions/BBANDS'
- $ref '#/definitions/DEMA'
Neither of which work of course. The reason is while the Indicator model describes an indicator correctly, different indicators can have a different parameter set.
Is there a way to essentially define a list of several models or perhaps map the BBANDS and DEMA models into Indicator?
Edit: Result of using #Helen's first suggestion in the Swagger Editor

Answer 1

Swagger/OpenAPI 2.0 does not support multiple types for items, but there are a couple of ways to describe what you need.
Option 1 - Model Inheritance
As long as you have one field that is common between the models and can be used to distinguish between them, you can use model inheritance:
https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#schemaDiscriminator
https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#composition-and-inheritance-polymorphism
In your example, this property is type (type="BBANDS" or type="DEMA"). So you can:
Inherit the BBANDS and DEMA models from Indicator by using allOf.
Add discriminator: type to Indicator to indicate that the type property will be used to distinguish between the sub-models.
Define Payload as an array of Indicator. This way it can actually be an array of BBANDS or an array of DEMA.
definitions:
Payload:
type: object
properties:
indicators:
type: array
items:
$ref: '#/definitions/Indicator'
Indicator:
type: object
properties:
type:
type: string
# Limit the possible values if needed
#enum:
# - BBANDS
# - DEMA
computeOn:
type: array
items:
type: string
default:
- close
# The "type" property will be used to distinguish between the sub-models.
# The value of the "type" property MUST be the schema name, that is, "BBANDS" or "DEMA".
# (Or in other words, the sub-model schema names must match possible values of "type".)
discriminator: type
required:
- type
BBANDS:
allOf:
- $ref: '#/definitions/Indicator'
- type: object
properties:
parameters:
type: object
properties:
timeperiod:
type: integer
format: int32
default: 5
nbdevup:
type: integer
format: int32
default: 2
nbdevdn:
type: integer
format: int32
default: 2
matype:
type: integer
format: int32
default: 0
DEMA:
allOf:
- $ref: '#/definitions/Indicator'
- type: object
properties:
parameters:
type: object
properties:
timeperiod:
type: integer
format: int32
default: 5
Option 2 - Single Model
If all parameters are integer, you can have a single model Indicator with parameters defined as a hashmap. But in this case you lose the ability to define the exact parameters for specific indicator types.
definitions:
Indicator:
type: object
properties:
type:
type: string
enum:
- BBANDS
- DEMA
computeOn:
type: array
items:
type: string
default:
- close
parameters:
type: object
properties:
# This is a common parameter in both BBANDS and DEMA
timeperiod:
type: integer
format: int32
default: 5
# This will match additional parameters "nbdevup", "nbdevdn", "matype" in BBANDS
additionalProperties:
type: integer

Answer 2

AFAIK in array type can holds one type, if you want to have multiple types under an array, then need to define another super type and wrap the subtypes in it ( May be using object type ) like bellow. This restriction is because swagger-2.0 doesn't support all the features of json-schema.org, oneOf, anyOf, allOf etc are some of it.
But you can make use the third party extension option available with swagger-2.0. Where you can name a Key with x-, so that means you can include these oneOf like x-oneOf and when parsing the schema you do that using json-schema parser along with swagger schema parser.
One such example is given bellow,
Json-schema
{
"id": "http://some.site.somewhere/entry-schema#",
"$schema": "http://json-schema.org/draft-04/schema#",
"description": "schema for an fstab entry",
"type": "object",
"required": [
"storage"
],
"properties": {
"storage": {
"type": "object",
"oneOf": [
{
"$ref": "#/definitions/diskDevice"
}
]
},
"deviceList": {
"type": "array",
"minItems": 1,
"items": {
"$ref": "#/definitions/Device"
}
}
},
"definitions": {
"diskDevice": {
"type": "object",
"properties": {
"label": {
"type": "string"
}
},
"required": [
"label"
]
},
"blockDevice": {
"type": "object",
"properties": {
"blockId": {
"type": "number"
}
},
"required": [
"blockId"
]
},
"CharDevice": {
"type": "object",
"properties": {
"charDeviceName": {
"type": "string"
}
},
"required": [
"charDeviceName"
]
},
"Device": {
"type": "object",
"oneOf": [
{
"$ref": "#/definitions/diskDevice"
},
{
"$ref": "#/definitions/blockDevice"
},
{
"$ref": "#/definitions/CharDevice"
}
]
}
}
}
Data or Payload
{
"storage": {"label": "adsf"},
"deviceList": [{"label": "asdf"}, {"blockId": 23}, {"charDeviceName": "asdf"}]
}
Use this site for play around with your sample data - http://www.jsonschemavalidator.net/
Note the deviceList property and how it got constructed. Hope this helps you.