Transient Keyword

Many times we are struggling with view state error on visualforce page at the time of uploading files.
Salesforce provides facility to a upload file upto 10mb, But when we try to upload file through visualforce page then visualforce page limit (135kb) create a wall. It is I try to jump this wall and upload the files through visual force page.

Using Transient Keyword  we can achieve this. Decalaring Variables as transient to reduces view states. View state maintains state of the Database between request and Visualforce page.

I try to explain this using code -

Controller

public class UploadFileDemo
{ 

    public Attachment attch{get;set;} 
    public Transient blob myAttachedBody {get; set;}
    
    public UploadFileDemo()
    {
          attch = new Attachment();
    }
    public void uploadFile()
    {
          attch.body = myAttachedBody;
          attch.parentId = parentIdOfRelatedObject;
          insert attch;
    }
}

VisualForce page

<Apex:page>

  <apex:form>

      <Apex:pageblock> 

          <apex:inputFile id="idSelectFile" fileName="{!attch.Name}"  value="{!myAttachedBody}" contentType="{!attch.contentType}"  ></apex:inputFile>

            <apex:commandbutton value="Upload" action="{!uploadFile}"/>

      </apex:pageblock>

  </apex:form>

</apex:page>