OpenAPI - how to describe query parameters?

Question

I'm trying to figure out how to document two of my query parameters in OpenAPI.

Filtering

My filtering follows the recommendations of JSON:API, which takes the form of, for example:

• ?filter[post]=1,2,3
• ?filter[post]=1,2,3&filter[author]=5

The filter key is an associative array that can contain a set list of resource names in my API. The value assigned to each filter key is either a single id or list of comma separated ids.

Sorting

For sorting also follows the JSON:API recommendation, so something like these:

• ?sort=age
• ?sort=age,-height

The sort query parameter is assigned the value of one sort field or list of comma separated sort fields. Note that the minus sign that prefixes the height field indicates a descending sort.

Question

How do I represent the my filtering and sorting in OpenAPI?

For example, I'm not sure it's possible for me to specify that the filter key is an associative array, or that it accepts a comma separated list of ids. Almost the same issue for sort: how to represent a comma separated list of sort fields?

Answer 1

The below approach should help

parameters:
  - in: query
    name: fields
    style: deepObject
    allowReserved: true
    schema:
      type: object
      properties:
        post:
          type: string
        author:
          type: string
  - in: query
    name: sort
    schema:
      type: array
      items:
        type: string
        enum:
          - age
          - height

A part of it is similar to the question that @Helen shared. It'll enable you to use it as in the below image

And the respective cURL command

curl -X GET "https://editor.swagger.io/user?filter[post]=1,2&filter[author]=3,4&sort=age&sort=height" -H  "accept: */*"

You can also define the filter parameter in below way

parameters:
  - in: query
    name: filter
    style: deepObject
    allowReserved: true
    schema:
      type: object
      properties:
        post:
          type: array
          items:
            type: string
        author:
          type: array
          items:
            type: string

This will result in the UI being more comprehensive as below

Then the cURL request looks as below

curl -X GET "https://editor.swagger.io/user?filter[post]=1&filter[post]=2&filter[author]=3&filter[author]=4&sort=age&sort=height" -H  "accept: */*"

And you should probably not need anyOf as it's related to inheritance for situations when a method may return an object of the base class or any of its sub-class.

Refer oneof-anyof-allof-not - OpenAPI Specification for more info on it.

Answer 2

This may be a bit old but I'm currently documenting an API whose sort, filter and dynamic relationship includes adheres to the JSON API spec and I just figured out how to properly document the filter query parameter. The below is written in JSON but I hope you'd be able to adapt it to fit your needs if you're writing YAML

{
    "schema": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "id": {
          "description": "Id of the user",
          "type": "string"
        },
        "referrer_id": {
          "description": "The id of the user that referred the user",
          "type": "string"
        },
        "email_verified": {
          "description": "Whether the user has verified their email address",
          "type": "boolean"
        },
        "trashed": {
          "description": "Whether the user has been soft deleted",
          "type": "string",
          "enum": [
            "with",
            "only"
          ]
        }
      }
    },
    "in": "query",
    "name": "filter",
    "description": "Really long description.........",
    "style": "deepObject",
    "explode": true,
    "allowReserved": true
  }

To document sorting, you can follow the example included here which is also written below

parameters:
  - in: query
    name: ids
    description: One or more IDs
    required: true
    schema:
      type: array
      items:
        type: integer
    style: form
    explode: false
    examples:
      oneId:
        summary: Example of a single ID
        value: [5]   # ?ids=5
      multipleIds:
        summary: Example of multiple IDs
        value: [1, 5, 7]   # ?ids=1,5,7

Answer 3

For sort its straight forward approach you can find syntax on official guide Open API Guide

For sorting: JSON format

"parameters": [{
    "in": "query",
    "name": "sort",
    "schema": {
        "type": "array",
        "items": {
            "type": "string"
        }
    }
}

]

YAML format

  parameters:
  - in: query
    name: "sort"
    schema:
    type: array,
    items:
      type: string