Compile Error: Loop must iterate over a collection type: SOBJECT:FeedItem

Question

I am new to Apex and I have the following code to call a function each time a new Chatter post is created:

public class MLPost {

    public static void MLPostCreate(FeedItem post) {

        for (FeedItem p : post){
          MLProjectHttpCallout.postContent(p.Body);
        }
    }
     }

I am getting this error and don't know what it means:

Compile Error: Loop must iterate over a collection type: SOBJECT:FeedItem

My trigger to call the above code is as follows:

trigger MLPostTrigger on FeedItem (before insert) {

    FeedItem posts = Trigger.new;

    MLPost.MLPostCreate(posts);
}

I get the following error when trying to compile the trigger code:

Error: Compile Error: Illegal assignment from LIST to SOBJECT:FeedItem at line 3 column 5

Any help would be greatly appreciated.

Answer 1

Update this particular line with this

public class MLPost {

    public static void MLPostCreate(List<FeedItem> posts) {

And update your trigger

trigger MLPostTrigger on FeedItem (before insert) {

  List<FeedItem> posts = Trigger.new;

  MLPost.MLPostCreate(posts);
  //  or you could also use 
  //  MLPost.MLPostCreate(trigger.new);
}

Explanation Actually trigger.new returns a list of SObjects, so in both the class and trigger code you should work with List. Hence, the error.