deleteImageRef() {
    let storage = firebase.storage();
    let imageRef = storage.refFromURL(this.imageUrl);

    let me = this;
    imageRef.delete().then(function() {
      me.imageUrl = null;
    }).catch(function(error) {
      console.log('error', error);
    });
  }

 uploadImage() {
   let storageRef = firebase.storage().ref();
   let path = Date.now().toString() + '-' + this.file.name;
   let iRef = storageRef.child('posts/' + path);
   let me = this;
   iRef.put(this.file).then((snapshot) => {
       let snackBarRef = this.snackBar.open('Image uploaded', 'OK!', {
         duration: 3000
       });
       this.storageRef.child('posts/' + path).getDownloadURL().then(function(url) {
         me.imageUrl = url;
         me.newThumbnail = url;
       });
   });
 }

		return new Promise((resolve, reject) => {
			firebase.storage()
				.ref(ref)
				.getDownloadURL()
				.then((url) => {
					resolve(url);
				}).catch((error) => {
					switch (error.code) {
						case "storage/object_not_found":
							reject("File doesn't exist");
							break;
						case "storage/unauthorized":
							reject("User doesn't have permission to access the object");
							break;
						case "storage/canceled":
							reject("User canceled the upload");
							break;
						case "storage/unknown":
							reject("Unknown error occurred");
							break;
					}
				});
		});