Firebase Fetch - No Access-Control-Allow-Origin

Question

I'm developing an app with React + Redux and I have my JSON database within a Firebase DB. To do this I'm tryin to fetch my data from a valid URL (validated from Firebase simulator)

let firebase = 'https://******.firebaseio.com/**/*/***/*' 
    return (dispatch) => {
        return fetch(firebase)
            .then(res => res.json())
            .then(json => dispatch({ type: 'GET_JSON', payload: json }))
    }

This returns to me the error:

Fetch API cannot load https://console.firebase.google.com/project/****/database/data/**/*/***/*. Redirect from 'https://console.firebase.google.com/project//database/data/**///' to 'https://accounts.google.com/ServiceLogin?ltmpl=firebase&osid=1&passive=true…ole.firebase.google.com/project//database/data///**/' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.`

I've tried many solutions, like adding to fetch's second argument { mode: 'no-cors', credentials: 'same-origin'}, but when I try this i get Uncaught (in promise) SyntaxError: Unexpected end of input.

What am I missing?

Answer 1

likely error that arise to  cors blocked when using firebase is
when you initiate a put or get request with an incomplete firebase url
e.g
// wrong form
 this.http.get('https://******.firebaseio.com/data')   //this will throw an exception

// correct form                                                    
  this.http.get('https://******.firebaseio.com/data.json')