How to serialize a regular expression type using .NET XML serialization

Question

How can I serialize a string from XML into a class property of type Regex ?

Here's the elements in the XML file:

  <IncludeRegex><![CDATA[#include\\s*\\\"\\s*(?<FileName>.+\\\\*\\.*.+)\\s*\\\"]]></IncludeRegex>
  <IncludeDefineRegex><![CDATA[#define\s*[A-Za-z_0-9]+\s*\""\s*(?<FileName>.+\.[a-zA-Z0-9]+)\s*\""]]></IncludeDefineRegex>

In my class, that I serialize, I have these properties:

public Regex IncludeRegex { get; set; }
public Regex IncludeDefineRegex { get; set; }

The rest of the class serializes without a problem, but the Regex properties fail to serialize. One option is to have alternate properties:

public string IncludeRegex { get; set; }
public string IncludeDefineRegex { get; set; }
[XmlIgnore]
public Regex IncludeRegexActual { get; private set; }

[XmlIgnore]
public Regex IncludeDefineRegexActual { get; private set; }

And set these properties in the setters of IncludeRegex and IncludeDefineRegex or an init function. This works, but can I do it without the duplicate properties?

Answer 1

I don't think you can do that with regular XML serialization, you have to implement IXmlSerializable to control the serialization directly.

Answer 2

The problem is, that Regex cannot be serialized. That can be solved by implementing IXmlSerializable . As you cannot change the Regex class, you have to handle it in another class. You might be able to do something like this (untested, out of my head):

public class MyRegEx : Regex, IXmlSerializable {...}

Now you have to implement the interface and have to use that class instead of Regex.