XmlConfiguration

Reader for XML configuration files and XML documents.

To use it, load existing XML file or use parse method to pass XML in a string:

var config =  ConfigurationReader.Load(@"C:\Temp\config.xml");
var another = ConfigurationReader.Parse(verbatim_xml);

All configuration nodes are located under the Root element. Reference them as if they were properties. For instance to read string value of LogDirectory element one can access it like this:

string dir = config.Root.LogDirectory;

Reading numbers:

double f = config.Root.SomeFactor;

Placing type name (string, double) instructs configuration reader to attempt to convert element's value. If conversion fails, runtime exception will be thrown.

Attribute access uses the same syntax as property access. Given <Item id='5'> we can access it as follows:

int id = config.Root.Item.id;

Using defaults for optional values

If some values are optional (may be missing) we can use defaults:

var f = (double?)config.Root.SomeFactor ?? 1.0;

Note the cast to nullable double. If SomeFactor element is missing, 1.0 will be assigned to f. If SomeFactor is present and well-formed its value will be assigned to f. We can still encounter an exception if SomeFactor exists, but is malformed.

Access to repeated elements

Indexing can be used to read N-th element.

var item = config.Root.Items[2];  // get third element under the node <Items>

Iterating over elements

Shallow iteration over direct descendants of selected node:

foreach (var item in config.GetElements(config.Root.Items))
    Console.WriteLine((string)item.Value);

or shorter:

foreach (var item in config.Root.Items)
    Console.WriteLine((string)item.Value);

To iterate over all descendant elements (deep, recursive):

foreach (var item in config.GetElements(config.Root.Items, deep: true))
    Console.WriteLine((string)item.Value);

Iterating over element attributes

Apart from directly accessing attributes with dot notation, we can also iterate over all of them:

foreach (var a in config.GetAttribute(config.Root.Item))
    Console.WriteLine($"attribute: {a.Name} value: {(string)a.Value}");

Testing nodes for existance

Building paths to missing elements is not going to throw; attempts to dereference them may. We can always test for their existance:

var element = config.Root.SameElement.AndAnother.OneMore;
if (config.Exists(element))
    ...

Missing elements

Given path to a missing element one can attempt to read it, like so:

string maybe_value = config.Root.SameMissingElement;
double? maybe_number = config.Root.AnotherMissingElement;

In this case maybe_value will be null, while maybe_number.HasValue will be false.

However, this will fail with runtime exception if AnotherMissingElement is missing:

double need_number = config.Root.AnotherMissingElement;

There are no null doubles.

Parsing user-defined types, extending XML configuration reader

Default XML reader can parse basic C# types (numbers, bool, TimeSpan, string). If you want to handle anything else converter function will be needed.

Let's try to add support for System.Windows.Media.Color type. Define converter function first:

static bool ColorConverter(string value, Type type, out object result)
{
   if (type.FullName == "System.Windows.Media.Color")
   {
       result = System.Windows.Media.ColorConverter.ConvertFromString(value);
       return true;
   }
   else
   {
       result = null;
       return false;
   }
}

Then attach it to the configuration reader to parse Color values:

config.Converter = ColorConverter;
System.Windows.Media.Color c = config.Root.SomeColor;

mikekov / XmlConfiguration