interface Note{
imageUrl: string;
title: string;
body: string;
titledesc: string;
imgalt: string;
imgdesc: string;
imgtitle: string;
authorId: string;

}

notesCollection: AngularFirestoreCollection<Note>;
  notes: Observable<Note[]>;

getAuthorData = function(blog: string){
this.notesCollection = this.afs.collection('/Blogs', ref =>{
  return ref.where('title','==', blog)

}).valueChanges()
this.notesCollection.subscribe( data => {
    console.log(data.authorId)
});
}