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# Multipart file upload

Multipart requests combine one or more sets of data into a single body, separated by boundaries.
You typically use these requests for file uploads and for transferring data of several types in a single request
(for example, a file along with a JSON object).

**`openapi.yml`**

```yml title="openapi.yml" maxLines=0 {12-24}
paths:
  /upload:
    post:
      summary: Upload a file
      description: Upload a file using multipart/form-data encoding
      operationId: uploadFile
      tags:
        - file
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                file:
                  type: string
                  format: binary
                  description: The file to upload
                description:
                  type: string
                  description: A description of the file (optional)
              required:
                - file
      responses:
        "200":
          description: Successful upload
          content:
            application/json:
              schema:
                type: object
                properties:
                  message:
                    type: string
                  fileId:
                    type: string
```

Any request body that is defined with a `multipart/form-data` content type, will be
treated as a multipart request. Within a given multipart request, a string parameter with
`format:binary` will represent an arbitrary file.

## Array of files

If your endpoint supports an array of files, then your request body must use
an array type.

**`openapi.yml`**

```yml openapi.yml {12-17}
paths:
  /upload:
    post:
      summary: Upload multiple files
      operationId: uploadFiles
      requestBody:
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                files:
                  type: array
                  items:
                    type: string
                    format: binary
                  description: An array of files to upload
```

> Document endpoints with the `multipart/form-data` content type