在尝试与其共享密钥之前，有什么方法可以验证 @Sign 是否存在？

Question

I am using the @protocol in a Flutter app and was wondering if there was a way to verify if another @sign exists before trying to share a key with it. For now I made a function that will try to share a key with the specified @sign. If there is an AtLookUpException , I consider the user non-existent:

 /// Check if user exists in this namespace by trying to share a key with them
  Future<bool> checkForUser(String atSign) async {
    /// Do test send to see if @ sign exists
    AtKey testKey = AtKey();
    testKey.key = 'test';

    testKey.sharedWith = atSign;

    try {
      await atProtocolService.atClientImpl.put(testKey, 'Are you there?');
      return true;
    } on AtLookUpException catch (e){
      print('AtLookUpException: '+ e.errorMessage);
      return false;
    }

}

For further verification, you could check the error message of the AtLookUpException which will look like this:

Secondary server not found: No secondary url found for atsign: @bob

Is this the best or quickest way to do this?

Answer 1

There is a library available to you that you can use:

https://github.com/atsign-foundation/at_libraries/tree/master/at_server_status

Feel free to adapt any part of the code as you like to fit your use case.

As always, your feedback is welcome.