Question

I’d like to use the EntLib 4.1 in my current project, specifically Unity 1.2 and the VAB. My application is an SaaS application, so I’ve made a decision to store tenant-specific configuration files in the database, to be loaded on tenant sign-in. These files include the VAB config and Unity config, as well as other tenant-specific settings.

I can’t find any practical way to simply use an XML string as my configuration info for the VAB.

I first thought that I’d have to create a custom implementation of IConfigurationSource, but then I realized that I would have to duplicate the parsing logic already present in the FileConfigurationSource class.

The next thought was that I could create a new class that derives from FileConfigurationSource, and just use the new class as a proxy to pass in the config info instead of a string with the file path, but I couldn’t see how to override the place where the file is loaded.

I checked out the SqlConfigurationSource QuickStart sample, but that again is not really what I think I need.

Answer 1

Here is the solution that I came up with to solve this issue:

I created a new class, XmlConfigurationSource, that derived from IConfigurationSource:

public class XmlConfigurationSource : IConfigurationSource
    {
        private string _xml;

        public XmlConfigurationSource(string xml)
        {
            _xml = xml;
        }
        //Other IconfigurationSource members omitted for clarity. 
        //Also, I'm not using them so I didn't implement them

        public ConfigurationSection GetSection(string sectionName)
        {
            //Since my solution is specific to validation, I'm filtering for that here.
            //This could easily be refactored for other EntLib blocks 
            //SerializableConfigurationSection object instead of XmlValidatorSettings
            if (sectionName != "validation")
                 return null;

             XmlValidatorSettings x = new XmlValidatorSettings(_xml.ToString());

             return x;            
         }
     }

The XmlValidatorSettings class was sort of the key to get this working. It’s a very simple class deriving from ValidationSettings:

public class XmlValidatorSettings : ValidationSettings
    {
        public XmlValidatorSettings(string configXml)
        {
            XDocument doc = XDocument.Parse(configXml);
            DeserializeSection(doc.CreateReader());
        }
    }

To use this code you’ll need to reference the EntLib common and validation DLL’s. Hope other people benefit from this!