When to dispose SPWeb and SPSite objects

Question

I am writing code in feature receiver, and I am wondering when to dispose SPWeb and SPSite objects.

For example, I have this in my code:

SPWeb web = properties.Feature.Parent as SPWeb;

Do I dispose the web object in this case? I know I should not do it if it's in SPContext, but what about properties.Feature?

My second case is, I have also a method that accepts SPSite as a parameter, so I pass myweb.Site to this method. Should I dispose the Site object I passed as below?

    public string doSomething(SPSite site)
        {
         //some code here
        }

third case, can anyone confirm that I must dispose web objects returned by OpenWeb function?

Answer 1

Do I dispose of the web object in this case?

No. Do not dispose SPFeatureReceiverProperties.Feature.Parent , For more details check SPFeatureReceiverProperties.Feature.Parent

Should I dispose of the Site object I passed as below?

In this case,Site is a reference variable type that by default passed by value in C# , So for reference type only the reference for the same object that has been copied not the entire object .

So you don't need to dispose it at the called function doSomething, it's sufficient to dispose it at the originalmethod method , so your code should look like

Public void originalmethod () { 

using (SPSite site = new SPSite("moss")) 
  { 

    doSomething(site); 
   }

 } 

 public string doSomething(SPSite site) {//don't dispose site object here}  

Can anyone confirm that I must dispose of web objects returned by OpenWeb function?

Consider

SPSite siteCollection = new SPSite("http://moss");
SPWeb web = siteCollection.OpenWeb();

So OpenWeb() will construct a new SPWeb object which you actually have to dispose of as

using (SPSite siteCollection = new SPSite("http://moss")) 
  { 
    using (SPWeb web = siteCollection.OpenWeb()) 
    { 
    } // SPWeb object web.Dispose() automatically called. 
  }  // SPSite object siteCollection.Dispose() automatically called. 

Also at event receiver, it should be disposed as

 SPWeb web = properties.OpenWeb()

  web.dispose();

For more details check Disposing SPWeb and SPSite objects