Get link to my images using filename not by dropbox-generated ID.

To get a (non-temporary) shared link via the Dropbox API, you can call the /2/sharing/create_shared_link_with_settings endpoint. You will need to identify the desired file in Dropbox, which you can do by file path or ID. You can modify the resulting links for different behaviors if needed.

To make that call, if you are able to construct the Dropbox file path directly from the filename information you have stored in your database, you can do so that way. Otherwise, you could use the /2/files/list_folder[/continue] endpoints to list the contents (including paths and IDs of files) under any particular path