File BLOB tool interface (create_blob_message)

[Karlostavitch1]

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I am trying to make a custom built-in tool for the DIFY project and have trouble understanding the create_blob_message tool interface.

According to the documentation:
File BLOB

If you need to return the raw data of a file, such as images, audio, video, PPT, Word, Excel, etc., you can use the following interface.

blob The raw data of the file, of bytes type

meta The metadata of the file, if you know the type of the file, it is best to pass a mime_type, otherwise, Dify will use octet/stream as the default type

def create_blob_message(self, blob: bytes, meta: dict = None, save_as: str = '') -> ToolInvokeMessage:
    """
        create a blob message

        :param blob: the blob
        :return: the blob message
    """

An example output I am receiving is:

{
"text": "Link: /files/tools/7819aadc-85de-4b2f-b7c2-1e8b17eeb5c9.bin\nLink: /files/tools/9e1b28c3-2cc9-4a98-8aa3-121e56b92381.bin\nLink: /files/tools/ac840a7b-1f9f-48f2-9fbc-3e18f2927658.pdf",
"files": [],
"json": []
}

It appears as if word, ppt, excel etc are just being saved as .bin files despite assigning the meta and save_as parameters and the links just point to an API endpoint, unusable in context.

I also note they are added to the text parameter in the output JSON, rather than files? not understanding what they are used for, is that expected behaviour?

I've tried finding as much documentation as I can, but I can't find specific information about the usage of this feature.

Is anyone able to enlighten me on the expected use and behavior of this interface please?