How to Use send_download in a Phoenix Controller for File Downloads

The article provides a comprehensive guide on using the send_download/3 function in Phoenix controllers to send files or binaries for user downloads. It outlines the function's syntax, which takes a connection struct, a kind (either a disk file path or in-memory binary), and a set of options for customizing the download experience. Key reasons for using send_download/3 include its ability to handle both file types with consistent API, automatic setting of download headers, and its utility in minimizing boilerplate code. Several practical examples are provided, demonstrating file downloads from disk, sending dynamically generated content, and using offset and length for partial file downloads. The article also highlights important considerations regarding security, filename encoding, browser handling, and the limitations of the function in certain situations (e.g., large file streaming). Finally, it suggests redirecting to a controller route from Phoenix LiveView for downloads, as direct downloads from LiveView socket handlers aren't supported.