firebase - Why use an object when denormalising data? -


in recent blog post on denormalising data, suggests logging of user's comments beneath each user so:

comments: {     comment1: true,     comment2: true }

why not list so:

comments: [     "comment1",     "comment2", ]

what advantages? there difference @ all? while i'm @ it, how go generating unique references these comments distributed app? imagining list i'd push them onto end , let array take care of index.

firebase ever stores objects. js client converts arrays objects using index key. so, instance if store following array using set:

comments: [   "comment1",   "comment2" ]

in forge (the graphical debugger), show as:

comments:    0: comment1    1: comment2

given this, storing id of comment directly key has advantage can refer directly in security rules, example, expression like:

root.child('comments').haschild($comment)

in order generate unique references these comments, please use push (https://www.firebase.com/docs/managing-lists.html):

var commentsref = new firebase("https://<example>.firebaseio.com/comments"); var id = commentsref.push({content: "hello world!", author: "alice"}); console.log(id); // unique identifier comment added.

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