Podio file attached to item cannot be downloaded - node.js

Question

I have an issue trying to download files attached to Podio items:
podio.request('get', '/file/{file_id}/raw').then(console.log);
The above program displays:
{}
This is a JSON stringified empty object (instead of raw file content).
Details:
The above file can be accessed with its URL when logged in
The above code is run after proper authentication
It actually works when using a file_id from an image field of the item, but not from a file attachment (pdf files in my case).
When using API endpoint /item/app/{app_id}/filter to get a list of items, the property file_count is set, but not files. I have to request /item/{item_id} individually to get the files property included in the response, not sure why.
Question: Do you know what is the issue, and how I can download raw attached files?
EDIT: aditionnal info
If I request a single file metadata using the folowing command:
podio.request('get', '/file/1234').then(console.log);
I get a file JSON object which includes many fields, but not the file content :
{
...
link: 'https://files.podio.com/1234',
file_id: 1234,
...
}
As stated in my comment to #stengaard, if I try to request the API for the above link, here is the response :
{ [PodioNotFoundError: [object Object]]
message:
{ error_parameters: {},
error_detail: null,
error_propagate: false,
request:
{ url: 'http://api.podio.com/1234',
query_string: '',
method: 'GET' },
error_description: 'No matching operation could be found. The path \'/1234\' was not found..',
error: 'not_found' },
status: 404,
url: 'https://api.podio.com:443/1234',
name: 'PodioNotFoundError' }

Answer 1

To use the GET /file/{file_id}/raw endpoint you need an API key with elevated trust levels.
Instead use GET /file/{file_id} endpoint. That contains a link attribute (a URL) you should follow to get the file content.
The link attribute will look like: https://files.podio.com/{file_id}. To fetch the file do https://files.podio.com/{file_id}?oauth_token={oauth_token}. Where the OAuth token is the same as the one used to GET /file/{file_id}. If you know the file ID (e.g. from a GET /item/{item_id} you can skip the GET /file/{file_id} and contact files.podio.com directly. (Note: You can also set the Authorization: OAuth2 {oauth_token} header in your HTTP request if you don't like passing the auth token in a URL paramter.)
For an example on how to use it see https://github.com/podio/podio-js/blob/master/lib/general.js#L11
Typically in the JS client, if you use podio as your Podio API object, the OAuth token would be located there:
podio.authObject.accessToken
So to get the raw content of the file in nodejs:
var url = 'https://files.podio.com/'+file_id+'?oauth_token='+podio.authObject.accessToken;
request(url, function (err, fileContent) {
// use fileContent here, write to a file, etc...
});

Answer 2

It seems your request has an error.
please try the below method and get raw file content from its response.
podio.request('get', '/file/{file_id}').then(console.log);
FYI, we couldn't get the files by filtering the items. we need to request /item/{item_id} individually to get the files property as you said.