Polymer + Firebase 3

[rof2...@gmail.com]

I want to save an object, but i am get errors:

this is my firebase-document:

<firebase-document

      id="ref"

      path="{{firebaseURL}}/[[user.uid]]"

      data="{{contato}}"

      log>

    </firebase-document>

this is my method:

saveContact: function() {

   this.$.ref.save(this.$.ref.path, this.contato);

}

I am get this error: 

firebase.js:318 Uncaught (in promise) Error: Firebase.child failed: First argument was an invalid path: "XXXXX/user/5iTMV0vyigOIvHpG00puivCdsfA3/[object Object]". Paths must be non-empty strings and can't contain ".", "#", "$", "[", or "]"(…)

I need help, thanks.

Rodolfo Azevedo

[rof2...@gmail.com]

I can save now, but now my problem is that Sync, I do not want to sync, only to save an object.

I need help on this, thanks.