Opening a Postgres Connection in Xamarin returns Error While Connecting - postgresql

Question

I am trying to connect my Android Application to Postgres but seems not to work.
The Exception Message is: Exception while Connecting
This is my Code Behind,
private void Login_Clicked(object sender, EventArgs e)
{
DBInterface<DBLogicInput, DBLogicResult> dbLoginLogic = new DBLoginLogic();
DBLogicInput userInput = new DBLogicInput();
DBLogicResult DBResult = new DBLogicResult();
LoginModel useCredentials = new LoginModel()
{
userName = txtUsername.Text,
passWord = txtPassword.Text
};
userInput[typeof(LoginModel).FullName] = useCredentials;
try
{
DBResult = dbLoginLogic.DoProcess(userInput);
bool userExisting = DBResult.ResultCode != DBLogicResult.RESULT_CODE_ERR_DATA_NOT_EXIST;
if (userExisting)
{
Application.Current.MainPage = new NavigationPage(new IndexPage());
}
else
{
_ = DisplayAlert("Login Error", "User does not exist", "Ok");
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
This is the Class I created to connect the DB.
public abstract class DBLogic : DBInterface<DBLogicInput, DBLogicResult>
{
public string connectionString = "Server=localhost;Port=5432;User Id=postgres;Password=postgres;Database=proyektoNijuan";
public DBLogicResult DoProcess(DBLogicInput inOut)
{
//throw new NotImplementedException();
DBLogicResult result = default(DBLogicResult);
NpgsqlConnection connection = null;
NpgsqlTransaction transaction = null;
try {
connection = new NpgsqlConnection(connectionString);
if (connection.State != System.Data.ConnectionState.Open)
{
connection.Open();
}
transaction = connection.BeginTransaction();
result = Process(connection, inOut);
transaction.Commit();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
transaction.Rollback();
} finally {
if (connection != null)
{
connection.Close();
}
}
return result;
}
protected abstract DBLogicResult Process(NpgsqlConnection conn, DBLogicInput InOuT);
}
The error exists after the debugger hits the code connection.Open();.
Should I add a web services to connect the postgres to my android app built in xamarin forms?
I am only a beginner in Xamarin Forms. I am just trying to create a self application. And need a little help for me to learn a new platform in programming.
Thank you and Regards,
How to fix it?

Answer 1

Well, I think I am doing it wrong.
Maybe the Right way to Connect the PostgreSQL is to have a WEB API.
Calling that web API to the Xamarin forms.
I really don't know if it is correct, but I will give it a try.
I will update the correct answer after I finish the development of that WEB API so that other beginners will found this answer helpful.