如何在ConfigurationElementCollection中按键查找

Question

I have a class which inherits from ConfigurationElementCollection. I want to add a function called FindByKey which returns the ConfigurationElement with a specific key. The key will be a string and I know that the ConfigurationElement stores the key as an object.

Does anyone have any simple code to detect the element from the key? I am sure that a simple answer is based on knowing the ConfigurationElementCollection properties and quickly converting between string and object.

Thanks J

Answer 1

I have an example I completed today, as I am writing an extension for the ConfigurationElementCollection class. It may not be very optimal, but it has a similar method to the one you're asking about for ContainsKey(key).

public class ConfigurationElementCollectionExtension : ConfigurationElementCollection, IConfigurationElementCollectionExtension
    {
        protected override ConfigurationElement CreateNewElement()
        {
            throw new NotImplementedException();
        }

        protected override object GetElementKey(ConfigurationElement element)
        {
            throw new NotImplementedException();
        }

        bool IConfigurationElementCollectionExtension.ContainsKey<T>(T key)
        {
            bool returnValue = false;

            object[] keys = base.BaseGetAllKeys();

            string keyValue = key.ToString();
            int upperBound = keys.Length;
            List<string> items = new List<string>();

            for (int i = 0; i < upperBound; i++)
            {
                items.Add(keys[i].ToString());
            }

            int index = items.IndexOf(keyValue);
            if (index >= 0)
            {
                returnValue = true;
            }


            return returnValue;
        }
    }

Answer 2

Kick start.... many samples out there.

public class MYAppConfigTool {

    private Configuration _cfg;

    public Configuration GetConfig() {
        if (_cfg == null) {
            if (HostingEnvironment.IsHosted) // running inside asp.net ?
            { //yes so read web.config at hosting virtual path level
                _cfg = WebConfigurationManager.OpenWebConfiguration(HostingEnvironment.ApplicationVirtualPath);
            }
            else { //no, se we are testing or running exe version admin tool for example, look for an APP.CONFIG file
                //var x = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
                _cfg = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            }
        }
        return _cfg;
    }

    public AppSettingsSection GetAppSettings() {
        var cfg = GetConfig();
        return cfg == null ? null 
                           : cfg.AppSettings;
    }

    public string GetAppSetting(string key) {
        // null ref here means key missing.   DUMP is good.   ADD the missing key !!!!
        var cfg = GetConfig();
        if (cfg == null) return null;
        var appSettings = cfg.AppSettings;
        return appSettings == null ? null 
                                   : GetConfig().AppSettings.Settings[key].Value;
    }
}