Unable to post files from JSONWS API page

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.1.30 EE GA3, 6.2.0 CE M3, 7.0.0 M3
• Fix Version/s: 6.2.5 CE GA6, 6.2.X EE, 7.0.0 M5
• Component/s: Frontend Infrastructure, Web Services, Web Services > JSON WS
• Labels:
  • QA-CT
  • liferay-fixpack-portal-84-6210
• Branch Version/s:
  6.2.x
• Backported to Branch:
  Committed
• Fix Priority: 3
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/25480

It is not possible to upload files from API page:

1. Log in as an administrator
2. Go to add-file-entry method: {domain}

   /api/jsonws?signature=%2Fdlapp%2Fadd-file-entry-9-repositoryId-folderId-sourceFileName-mimeType-title-description-changeLog-file-serviceContext

3. enter data, as follows, and select any file to upload:
   repositoryId: Guest groupId
   folderId: 0
   sourceFileName: some string, like "Test"
   mimeType: file extension, like "txt"
   title: string
   description: string, optional
   changeLog: string, optional
   Result: API call fails: "No JSON web service action with path /dlapp/add-file-entry and method null for /"
   Expected: Results tab shows the JSON object that is returned after uploading the file. Go to Admin > Content > Documents and Media and file uploaded should be listed.

The reason for this is that API page does not really submit a multipart POST request, but a regular one, and the File attribute is therefore missing, and method can not be matched.