I want to upload attachments from other apps to the attachment field of the current app through a custom button click
in the ['app.record.create.show', 'app.record.edit.show'] situation.
As a detailed process, I would like to have the sign image automatically entered into the attachment according to the person in charge.
You essentially want to retrieve the signature attachment of the currently logged-in user from like a user database app and have it automatically uploaded to a record in a different app whenever they create or edit one, correct?
The easiest way to achieve this using a native feature is with a Related Records field, as it can display an attachment field from another app.
If you want to accomplish this through customization, the process can be complex.
Here are the key steps:
Use the Kintone REST API (GET /k/v1/records.json) to retrieve the file key of the corresponding attachment.
With that being said, you need to download the file first, then re-upload it using the Kintone file API (POST /k/v1/file.json).
Once uploaded, you will receive a fileKey, which should be set to the attachment field.
For reference, here are useful help pages with sample implementations: