C＃winform应用程序在运行时运行CRUD ConnectionStrings

Question

I am making a program and i want for the user to be able to connect it to several Databases(SQL or MySQL) dynamically as he/she uses it. So i need to be able to Create Read Update and Delete connection strings (into the app.config ???) and make those changes persistent.

Till now i am able to do most of these things but they are not persistent.Here is some of my code.

    public static class CnnHelper
    {
      public static string ReadCnn(string name)
      {
        return ConfigurationManager.ConnectionStrings[name].ConnectionString;
      }
      public static void UpdateCnn(string name,string cnn)
      {
        ConfigurationManager.ConnectionStrings[name].ConnectionString = cnn;
      }
      public static void InsertCnn(string name, string connectionstring)
      {
        RemoveReadOnly();
        ConfigurationManager.ConnectionStrings.Add(new ConnectionStringSettings(name, connectionstring));
        AddReadOnly();
      }
      public static List<string> GetAllCnnNames()
      {
        return ConfigurationManager.ConnectionStrings
                                   .Cast<ConnectionStringSettings>()
                                   .Select(v => v.Name)
                                   .ToList();
      }
      private static void RemoveReadOnly()
      {
        typeof(ConfigurationElementCollection)
                .GetField("bReadOnly", BindingFlags.Instance | BindingFlags.NonPublic)
                .SetValue(ConfigurationManager.ConnectionStrings, false);
        //ConfigurationManager.ConnectionStrings.Add(new ConnectionStringSettings());
      }
      private static void AddReadOnly()
      {
        typeof(ConfigurationElementCollection)
                .GetField("bReadOnly", BindingFlags.Instance | BindingFlags.NonPublic)
                .SetValue(ConfigurationManager.ConnectionStrings, true);
        //ConfigurationManager.ConnectionStrings.Add(new ConnectionStringSettings());
      }
    }

Why it doesn't keep the changes ?

How i can do this?

Answer 1

I think ideally you should keep a user profile to manage the database connection strings for each user instead of letting them directly change the app config.

If you still prefer to use the app settings config file, then you need to use the Configuration.Save method to save the changes in the configuration.

Refer: https://docs.microsoft.com/en-us/dotnet/api/system.configuration.configuration.save?view=netframework-4.7.1

        // Add an entry to appSettings section.
        int appStgCnt =
            ConfigurationManager.AppSettings.Count;
        string newKey = "NewKey" + appStgCnt.ToString();

        string newValue = DateTime.Now.ToLongDateString() +
          " " + DateTime.Now.ToLongTimeString();

        config.AppSettings.Settings.Add(newKey, newValue);
config.Save(ConfigurationSaveMode.Full);