Then I take a look. I can't read anything anymore, nor time to learn like this. What I manage, and very slowly, is to see something that actually works and read it line by line. To try to understand why it worked.
If you, or someone, don't post how it should be done, I'll understand a lot, but I'll have to wait.
To the others who maybe go through this same question, I think I have 2 options: 1) Convert my image that is inside SPIFFS to base64, or 2) Change my mind and send my image to a storage site and get it from there to there to compose the final URL again.
Just to clarify, I have an ESP32 cam, which will take pictures every X seconds.
And I have access to an API that through a composite URL sends pictures. But the photos sent by the API are on an amazon AWS server. So inside the URL you have &image="http://etc etc etc"
That's what I'm trying to change. ESP-CAM will take pictures and temporarily store them in SPIFFS, then I will send the picture and delete it. Wait for new photo, store, send and delete, and repeat this forever.
I'm trying to make the compound URL from the API directly including the picture from SPIFFS.