Hi Bjorn,
Glad you like it :-)
Based on the discussion I had with Bruno, I also added VaryByExpression property, which allows you to use SpEL expressions instead of just parameter names to specify key elements. For example, you can do something like this:
[Cache(VaryByExpression = "#user.EMail")]
public IPermissionSet GetUserPermissions(User user)
{ .. }
As you can see, this allows you to use properties of one or more method arguments as key elements (you can separate multiple elements with commas, just like with VaryByParam property).
This is also fairly obvious from the example, but I'll state it anyway -- method arguments are passed to the expression engine as variables, keyed by argument name, so you need to use variable expression to access them within expression.
That said, CacheAdvice can already be considered somwhat of a legacy ;) I'm not even sure if it will remain in the codebase at this point, as there is a already a new implementation of the caching aspect that adds a number of features:
1. You can specify which named cache from the application context to store method result in. This allows you to use different caches for different purposes while still applying only a single aspect to your objects. This is not possible with the old implementation, as Cache is property of the advice, so you would have to define one cache advice per target cache and apply them selectively to your objects.
2. If the method returns a collection, you can cache either the collection itself, each of its items separately, or both. You can also use different named caches for the collection and individual items.
3. You can update value in cache based on the method argument. For example, if you pass an object to your DAO's Save method, you can updated cached value automatically as well.
4. You can invalidate one or more cache values (or even clear the whole cache), based on method arguments or return value.
Here is an example class with various caching-related attributes applied:
public sealed class InventorStore : IInventorStore
{
private IDictionary inventors = new ListDictionary();
public InventorStore()
{
Inventor tesla = new Inventor("Nikola Tesla", new DateTime(1856, 7, 9), null);
Inventor pupin = new Inventor("Mihajlo Pupin", new DateTime(1854, 10, 9), null);
inventors.Add("Nikola Tesla", tesla);
inventors.Add("Mihajlo Pupin", pupin);
}
[CacheResultItems("inventors", "Name")]
public IList GetAll()
{
return new ArrayList(inventors.Values);
}
[CacheResult("inventors", "#name")]
public Inventor Load(string name)
{
return (Inventor) inventors[name];
}
public void Save([CacheParameter("inventors", "Name")] Inventor inventor)
{
inventor.Nationality = "Serbian";
}
[InvalidateCache("inventors", Keys = "#inventor.Name")]
public void Delete(Inventor inventor)
{
}
[InvalidateCache("inventors")]
public void DeleteAll()
{
}
}
You can then apply CacheAspect to this class either programmatically:
CacheAspect cacheAspect = new CacheAspect();
cacheAspect.ApplicationContext = appContextContainingICacheInstances;
ProxyFactory pf = new ProxyFactory(new InventorStore());
pf.AddAspect(cacheAspect);
IInventorStore store = (IInventorStore) pf.GetProxy();
or declaratively:
<object id="cacheAspect" type="Spring.Aspects.Cache.CacheAspect, Spring.Aop"/>
<object id="inventorStore" type="Spring.Aop.Framework.ProxyFactoryObject, Spring.Aop">
<property name="Target">
<object type="DAL.InventorStore, MyDAL"/>
</property>
<property name="InterceptorNames" value="cacheAspect"/>
</object>
<object id="inventors" type="Spring.Caching.AspNetCache, Spring.Web"/>
As you can see, CacheAspect is a container holding all the advices and associated pointcut definitions that are necessary for everything to work. You can apply it to an object by simply adding its object ID to the list of interceptor names within ProxyFactoryObject definition.
As usual, feedback is appreciated.
Regards,
Aleks