title: Defaulting user-defined fields for records created before the customization
body: <p>I have a DAC extension that has a default attribute set for it(see definition below). I have noticed that for any records that existed prior to the DAC extensions existence will still hold a null value. Is there a conventional way that we can get all the records initialized?</p>
  
  <p>If not I will likely perform a check within an event handler before its used.
  Thanks in advance!</p>
  
  <pre><code>    public abstract class usrCustOptInOut : IBqlField
      {
      }
      protected string _UsrCustOptInOut;
      [PXDBString(1, IsUnicode = true)]
      [PXDefault(OptInOut.Default, PersistingCheck = PXPersistingCheck.Nothing)]
      [PXUIField(DisplayName = "Click To Pay Opt In/Out")]
      [PXStringList(
          new[]
          {
              OptInOut.OptOut,
              OptInOut.OptIn,
              OptInOut.Default
          },
          new[]
          {
              "Customer Opt Out",
              "Customer Opt In",
              "Default"
          })]
      public virtual string UsrCustOptInOut
      {
          get
          {
              return _UsrCustOptInOut;
          }
          set
          {
              _UsrCustOptInOut = value;
          }
      }
  </code></pre>