How to get the contents of a file attached to an Account with SOQL (Salesforce).

using-salesforce-files-externally.md

Files attached to Accounts in Salesforce are not publicly addressable. This gist explains how to use them in another context, so that they can be accessed by non-authenticated users. It assumes you are able to query Salesforce with the REST API connected via OAuth 2.0.

1. Get an account record identified by {id} and return any attached files:

SELECT Id, Name, (ContentDocumentid FROM AttachedContentDocuments) FROM Account WHERE Id = {id}

2. Use (one of) the returned ContentDocumentids to retrieve the a link to latest version of the file you're interested in. This will return an API URL that can be used to retrieve the file contents:

SELECT VersionData FROM ContentVersion WHERE ContentDocumentId = 'XXXXXXXXX' AND IsLatest = true

3. Request the API URL, e.g. /services/data/v46.0/sobjects/ContentVersion/YYYYYYYYY/VersionData to return the binary data of the file. You can either stream directly to the browser with appropriate headers, or (much better) save as a file and serve that to your non-authenticated users.