DML During Initialisation

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I ran into a situation recently where I wanted to be able to insert a record as part of the construction of a Visualforce controller, which the user then edited. As we all know, DML is not allowed in the constructor, so I started investigating alternatives.

One mechanism is to create an interim Visualforce page with a page action attribute tied to a controller method that inserts the record and then redirects the user to the actual Visualforce edit page. The downside to this method is that I would end up with two pages and two controllers, as its not safe for this to be incorporated into a single controller due to the fact that order of execution cannot be guaranteed.

An alternative solution, and the route that I chose to go, is to use javascript to invoke an action method on the controller, and have this action method carry out the DML operation. In order to ensure that this doesn't happen every time that the page is refreshed, I have an "initialised" flag in my controller that is set to false in the constructor, and updated to true once the DML has taken place.

The controller is shown below:

public class InsertObjectController 
{
 public Boolean initialised{get; set;}
 public Account acc {get; set;}
 
 public InsertObjectController()
 {
  initialised=false;
 }
 
 public void init()
 {
  if (!initialised)
  {
   acc=new Account();
   acc.Name='Blog Account';
   insert acc;
   initialised=true;
  }
 }
}

On the page side, the main change was to put out a please wait spinner while the initialisation was going on, so that the user wasn't tempted to start entering data while the initialisation was taking place. The DML operation is executed via an actionfunction tied to the onload handler, and once this completes the main body of the page is rerendered, replacing the spinner with the newly inserted record detail (including the id of the account).

Note that it this will overwrite any existing onload handler - for details of how to add a function to the end of the existing onload handler see this blog post.

The page markup is shown below:

<apex:page controller="InsertObjectController">
  <apex:form >
    <apex:actionFunction name="doInit" action="{!init}" rerender="allPanel"/>
    <apex:outputPanel id="allPanel">
      <apex:outputPanel rendered="{!NOT(initialised)}">
        <p align="center" style='{font-family:"Arial", Helvetica, sans-serif; font-size:20px;}'><apex:image value="/img/loading.gif"/>&nbsp;Please wait</p>
        <script>
           window.onload=function()
           {
             doInit();
           };
        </script>
      </apex:outputPanel>
      <apex:outputPanel rendered="{!initialised}">
        <apex:pageBlock title="Account Details">
          <apex:pageBlockSection >
            <apex:inputField value="{!acc.id}"/>
            <apex:inputField value="{!acc.name}"/>
            <apex:inputField value="{!acc.type}"/>
            <apex:inputField value="{!acc.industry}"/>
          </apex:pageBlockSection>
        </apex:pageBlock>
      </apex:outputPanel>
    </apex:outputPanel>
  </apex:form>
</apex:page>