Missing start boundary for multipart body

[naraesk]

Q&A (please complete the following information)

• OS: Linux
• Browser: Chrome / Firefox
• Version: 105/104
• Method of installation: npm
• Swagger-UI version: using swagger-jaxrs2-jakarta/2.2.2
• OpenAPI version: OpenAPI 3.0

Content & configuration

Example Swagger/OpenAPI definition:

openapi: 3.0.3
info:
  title: FormData MultiPart Example
  version: 1.0.0
paths:
  /foo:
    post:
      operationId: updatePet
      parameters:
        - name: id
          in: query
          required: true
          schema:
            pattern: ^(?!aliases$)(?!ids$)[-_.a-zA-Z0-9]+$
            type: string
        - name: additionalMetadata
          in: query
          description: Additional Metadata
          required: false
          schema:
            type: string
      requestBody:
        content: 
          multipart/form-data: # Media type
            schema:   
              type: string
              format: binary
      responses:
        '200':
          description: Successful operation

Describe the bug you're encountering

It seems that there is no start boundary set. Chrome Dev Tools also only show the end boundary but no start boundary. This leads to the following exception on the server:

Caused by: org.jvnet.mimepull.MIMEParsingException: Missing start boundary
at org.jvnet.mimepull.MIMEParser.skipPreamble(MIMEParser.java:288)
at org.jvnet.mimepull.MIMEParser.access$300(MIMEParser.java:38)
at org.jvnet.mimepull.MIMEParser$MIMEEventIterator.next(MIMEParser.java:124)
at org.jvnet.mimepull.MIMEParser$MIMEEventIterator.next(MIMEParser.java:102)
at org.jvnet.mimepull.MIMEMessage.makeProgress(MIMEMessage.java:199)
at org.jvnet.mimepull.MIMEMessage.parseAll(MIMEMessage.java:160)
at org.jvnet.mimepull.MIMEMessage.getAttachments(MIMEMessage.java:86)

To reproduce...

Steps to reproduce the behavior:
Just fill out the form and have a look at the request header

Expected behavior

There should be a start boundary set, but there isn't any.

Screenshots

Additional context or thoughts

The curl command produced by swagger-ui works as expected, there the start boundary is set.

[LouCastaldo]

Having same issue, has this been resolved ?

[hkosova]

@naraesk change the requestBody as follows:

      requestBody:
        content: 
          multipart/form-data:
            schema:
              type: object
              properties:
                myFile:  # The name of the form field that contains the file
                  type: string
                  format: binary

As explained in Multipart Requests, the request body schema must be type: object whose properties represent individual parts (form fields) of a multipart request.

[LouCastaldo]

My request looks like below. I get a 200 back but it only passes the pdf file as an attachement but does not pass the Json part at all. Any ideas ? The "encoding" keyword does not seem to do anything at all.

  requestBody:
    content:
      multipart/form-data:
          schema:
            description: The main schema representing the multipart body.
            type: object
            properties:
              json:
                $ref: '#/components/schemas/request-wrapper'
              files:
                type: array
                items:
                  type: string
                  format: binary
          encoding:
            json: 
              contentType: application/json
            files:
              contentType: application/pdf

components:
schemas:
request-wrapper:
type: object
properties:
SomeID:
type: string