Working With Generic Types In Unity Configuration Section
Working With Generic Types In Unity Configuration Section
In my previous post about Unity I 
discussed about configuration
files and how to configure Unity with
them. I got a question in the subject
of how to use generic types in the
configuration files. This post will
answer that question.
The Scenario
I have an interface of IValidator which receives a generic type T.
public interface IValidator<T>
{
#region Methods
void Validate<T>();
#endregion
}
Also, I have a class Validator which receives a generic type T and implement
the IValidator interface.
public class Validator<T> : IValidator<T>
{
#region IValidator<T> Members
public void Validate<T>()
{
// do something
}
#endregion
}
Instead of registering them in code I want to write the mapping in the configuration file.
How to do it?
The Configuration File
I return to the configuration file that I showed in the previous post. The only difference
is that I added a new type to map – the IValidator type. Also, I added a type alias to that
type. The configuration file:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="unity"
type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,
Microsoft.Practices.Unity.Configuration, Version=1.1.0.0,
Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
</configSections>
<unity>
<typeAliases>
<!-- Lifetime manager types should be inserted
if you need lifetime managers -->
<typeAlias alias="singleton"
type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager,
Microsoft.Practices.Unity" />
<typeAlias alias="external"
type="Microsoft.Practices.Unity.ExternallyControlledLifetimeManager,
Microsoft.Practices.Unity" />
<!-- User defined type aliases -->
<!-- An interface for logger implementation -->
<typeAlias alias="ILogger"
type="UnityExamples.Common.ILogger,
UnityExamples.Common" />
<!-- An abstarct class for database classes -->
<typeAlias alias="Database"
type="UnityExamples.Common.Database,
UnityExamples.Common" />
<typeAlias alias="IValidator`1"
type="UnityExamples.Common.IValidator`1,
UnityExamples.Common" />
</typeAliases>
<containers>
<container>
<types>
<type type="ILogger"
mapTo="UnityExamples.Common.FileLogger,
UnityExamples.Common">
<!-- Will be configured as singleton by the lifetime
manager above -->
<lifetime type="singleton" />
</type>
<type type="IValidator`1"
mapTo="UnityExamples.Common.Validator`1,
UnityExamples.Common">
<!-- Will be configured as singleton by the lifetime
manager above -->
<lifetime type="singleton" />
</type>
<type type="Database"
mapTo="UnityExamples.Common.CustomDatabase,
UnityExamples.Common">
<typeConfig
extensionType="Microsoft.Practices.Unity.Configuration.TypeInjectionElement,
Microsoft.Practices.Unity.Configuration">
<constructor>
<param name="connString" parameterType="System.String">
<value value="connection value..."/>
</param>
<param name="logger" parameterType="ILogger">
<dependency />
</param>
</constructor>
</typeConfig>
</type>
</types>
</container>
</containers>
</unity>
</configuration>
As you can see in order to write a generic type I use the ` sign followed
by the number of generic types that the interface/class receives. In my
example the IValidator interface receives only one generic type and
therefore I use 1.
The Code To Run The Example
The following code will run the configuration file and map the IValidator
to the Validator class with a string input as the generic type the Validator
gets.
IUnityContainer container = new UnityContainer();
var section =
(UnityConfigurationSection)ConfigurationManager.GetSection("unity");
section.Containers.Default.Configure(container);
var validator = container.Resolve<IValidator<string>>();
Summary
Lets sum up the post, I showed an example of how to use a Unity
configuration section with generic types. All you have to remember is the
` sign as the sign for a generic type in the configuration file.
CodeProject