How to post files in Swagger (OpenAPI)?

OpenAPI Specification 2.0

In Swagger 2.0 (OpenAPI Specification 2.0), use a form parameter (in: formData) with the type set to file. Additionally, the operation's consumes must be multipart/form-data.

  consumes:
    - multipart/form-data
  parameters:
    - name: file
      in: formData   # <-----
      description: The uploaded file data
      required: true
      type: file     # <-----

OpenAPI Specification 3.0

In OpenAPI Specification 3.0, files are defined as binary strings, that is, type: string + format: binary (or format: byte, depending on the use case). File input/output content is described with the same semantics as any other schema type (unlike OpenAPI 2.0):

Multi-part request, single file:

requestBody:
  content:
    multipart/form-data:
      schema:
        type: object
        properties:
          # 'file' will be the field name in this multipart request
          file:
            type: string
            format: binary

Multi-part request, array of files (supported in Swagger UI 3.26.0+ and Swagger Editor 3.10.0+):

requestBody:
  content:
    multipart/form-data:
      schema:
        type: object
        properties:
          # The property name 'file' will be used for all files.
          file:
            type: array
            items:
              type: string
              format: binary

POST/PUT file directly (the request body is the file contents):

requestBody:
  content:
    application/octet-stream:
      # any media type is accepted, functionally equivalent to `*/*`
      schema:
        # a binary file of any type
        type: string
        format: binary

Note: the semantics are the same as other OpenAPI 3.0 schema types:

# content transferred in binary (octet-stream):
schema:
  type: string
  format: binary

Further information:

• Considerations for File Uploads
• Special Considerations for multipart Content
• File Upload and Multipart Requests

finally i found answer for this, actually previously there is no support for file upload, now they updated swagger-ui.js file. You need to replace your old one with new and also you have to define these properties under Parameters for particular parameter:

 "paramType": "body",
 "dataType": "file",

Mine seems to work with

 "paramType": "formData",
 "dataType": "file",