curl --request POST \
  --url https://app.teable.ai/api/attachments/signature \
  --header 'Authorization: Bearer REPLACE_BEARER_TOKEN' \
  --header 'content-type: application/json' \
  --data '{"contentType":"image/png","contentLength":123,"expiresIn":3600,"hash":"xxxxxxxx","type":1,"baseId":"string"}'

{
  "url": "https://example.com/attachment/upload",
  "uploadMethod": "POST",
  "token": "xxxxxxxx",
  "requestHeaders": {
    "Content-Type": "image/png"
  }
}