main.dart

  if (_formKey.currentState.validate()) {
    dbRef.push().set({
      "name": nameController.text,
      "age": ageController.text,
      "type": dropdownValue
    }).then((_) {
      ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Successfully Added')));
      ageController.clear();
      nameController.clear();
    }).catchError((onError) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text(onError)));
    });
  }