Facebook Graph API Get Feed / Missing Wall Messages

Question

I am creating a basic application for a research project. Basically, we want to see if brain surgery modifies behavior based on user messages and user interactions. In other words, we are trying to read all wall posts from specific users.

My initial ideas were this: as long as the researcher is a friend with the subject, I can call https://graph.facebook.com/UID/posts and https://graph.facebook.com/UID/feed . The combination of the two should give me all the relevant posts.

This works great for some users, but for others, I get only some random messages, and many others. For some users, I get nothing at all. I cannot find any template when messages are displayed, and when not. Does anyone know what could be the problem and how to solve it?

I use read_stream permission.

Answer 1

The most likely answer is that the user has disabled access to the API platform in their settings or has blocked privacy in some of their messages.