Plugins: Compilation Extensions

In certain situations users may want to use more complex logic to calculate a value of an index entry field. To do this we have introduced an AbstractDynamicCompilationExtensionto RavenDB.

public abstract class AbstractDynamicCompilationExtension
{
public abstract string[] GetNamespacesToImport();

public abstract string[] GetAssembliesToReference();
}

where:

• GetNamespacesToImport returns a list of namespaces that RavenDB will have to import
• GetAssembliesToReference returns a list of full paths to assemblies

Example - Check if a given word is a palindrome

public static class Palindrome
{
public static bool IsPalindrome(string word)
{
	if (string.IsNullOrEmpty(word))
		return true;

	int min = 0;
	int max = word.Length - 1;
	while (true)
	{
		if (min > max)
			return true;

		char a = word[min];
		char b = word[max];
		if (char.ToLower(a) != char.ToLower(b))
			return false;

		min++;
		max--;
	}
}
}

public class PalindromeDynamicCompilationExtension : AbstractDynamicCompilationExtension
{
public override string[] GetNamespacesToImport()
{
	return new[]
		{
			typeof (Palindrome).Namespace
		};
}

public override string[] GetAssembliesToReference()
{
	return new[]
		{
			typeof (Palindrome).Assembly.Location
		};
}
}

Now we can use our Palindrome in our index definition.

store.DatabaseCommands.PutIndex("Dictionary/Palindromes", new IndexDefinition
{
Map = @"from word in docs.Words 
			select new 
			{ 
						Word = word.Value, 
						IsPalindrome = Palindrome.IsPalindrome(word.Value) 
			}"
});