CODEWITHSUNDEEP
c#.netconfigurationconfigurationmanager
Anders Abel
Anders Abel

Reputation: 69260

How to identify missing ConfigurationElement?

Using System.Configuration, how can I identify if a child configuration element is completely missing, or merely empty?

Test program

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MissingConfigElementTest
{
    class MyConfigurationElement : ConfigurationElement
    {
        [ConfigurationProperty("name")]
        public string Name
        {
            get { return (string)base["name"]; }
        }
    }

    class MyConfigurationSection : ConfigurationSection
    {
        [ConfigurationProperty("empty", DefaultValue = null)]
        public MyConfigurationElement Empty
        {
            get { return (MyConfigurationElement)base["empty"]; }
        }

        [ConfigurationProperty("missing", DefaultValue = null)]
        public MyConfigurationElement Missing
        {
            get { return (MyConfigurationElement)base["missing"]; }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var configSection = (MyConfigurationSection)ConfigurationManager.GetSection("mySection");

            Console.WriteLine("Empty.Name: " + (configSection.Empty.Name ?? "<NULL>"));
            Console.WriteLine("Missing.Name: " + (configSection.Missing.Name ?? "<NULL>"));

            Console.ReadLine();
        }
    }
}

Test Configuration

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="mySection" type="MissingConfigElementTest.MyConfigurationSection, MissingConfigElementTest"/>
  </configSections>
  <mySection>
    <empty />
  </mySection>
</configuration>

Output

The output is

Empty.Name: 
Missing.Name:

The Problem

I can't find a way to differentiate between the empty, but present configuration element and the case where the entire configuration element has been left out.

I want to have this because if an element is present, I want to make sure that it passes certain validation logic, but it is also fine to just leave the element out entirely.

Upvotes: 2

Views: 1061

Answers (2)

Kompiler
Kompiler

Reputation: 176

To add to this, the ElementInformation.IsPresent property can be used to determine whether the element exists within the original configuration.

var configSection = ( MyConfigurationSection ) ConfigurationManager.GetSection( "mySection" );

Console.WriteLine( "Empty.Name: " + ( configSection.Empty.ElementInformation.IsPresent ? configSection.Empty.Name : "<NULL>" ) );
Console.WriteLine( "Missing.Name: " + ( configSection.Missing.ElementInformation.IsPresent ? configSection.Missing.Name : "<NULL>" ) );

Console.ReadLine( );

This will output

Empty.Name:
Missing.Name: <NULL>

Upvotes: 5

jgauffin
jgauffin

Reputation: 101150

You can search for the section:

var sections = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None).Sections;
var exists = sections.Cast<ConfigurationSection>()
                .Any(x => x.SectionInformation.Type.StartsWith("MissingConfigElementTest.MyConfigurationSection"));

Upvotes: 2

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