apex:actionFunction and Database.Update() unintended page refresh - ajax

Question

So, I've been working on an "edit item" modal for a visualforce page that will allow the user to edit a child component of an object, and refresh the page. As it stands, there is a single URL parameter that contains the parent objects ID. The code is structured very similar to this:
<apex:form id="edit-modal">
<!-- Modal Content-->
<apex:actionFunction action="{!updateModalObject}" name="updateModalObject">
</apex:actionFunction>
</apex:form>
When the user preses a "save" button in the modal, the aforementioned actionfunction is called. The class in the controller looks like this:
public PageReference updateModalObject(){
database.update(modalObject);
return null;
}
When this action completes, the page is refreshing, also dropping the URL parameters and causing the whole thing to sort of.. gum up. I'm not sure which portion of the code is causing the refresh, if it's the actionfunction or if it's the update in the controller.

Answer 1

You said:
When the user preses a "save" button...
I think this is causing the page refresh. Do you use the command button without reRender tag? The solution might look like this:
Just try this trick out - add return false after executing your JavaScript function:
<apex:commandButton value="Save" onclick="updateModalObject(); return false;"/>
Other way to avoid page reload is to add a dummy reRender tag:
<apex:commandButton value="Save" onclick="updateModalObject()" reRender="none" />
or
<apex:actionFunction action="{!updateModalObject}" name="updateModalObject" reRender="none">
You must to re-render "something" to avoid the page reload. Otherwise the command button will reload the whole page. In our case we will re-renden "nothing".