Can apex:param pass null for Integers?

Question

I'm trying to reset an Integer value to null, but it is converted to 0.

<apex:actionFunction action="{!doSomething}" name="doSomething" rerender="nothing">
    <apex:param name="indexValue" assignTo="{!index}" value="{!NULL}" />
</apex:actionFunction>

public class MyController{
    public Integer index { get; set; }

    public void doSomething() {
        System.debug(index);
    }
}

Is there way to set it to null?

Answer 1

It looks like the problem is that when the parameter comes over as an empty string, salesforce converts the value to 0 instead of NULL. You could consider setting the value of index in your method based on the param value string:

public void doSomething() {
    String ParamValue = Apexpages.currentPage().getParameters().get('indexValue');
    index = ParamValue == '' ? NULL : Integer.valueOf(ParamValue);
    System.debug(index);        
}

Answer 2

If you are always trying to clear out index in doSomething, just assign it in Apex.

public void doSomething()
{
    index = null;
    system.debug(index);
}

Otherwise you could add a Boolean clearIndex property and set that instead.

public Boolean clearIndex { get; set; }
public void doSomething()
{
    if (clearIndex) index = null;
    clearIndex = false;
}

Then in your markup, change your actionFunction to:

<apex:actionFunction action="{!doSomething}" name="doSomething" rerender="nothing">
    <apex:param name="toClear" assignTo="{!clearIndex}" value="{!true}" />
</apex:actionFunction>

Answer 3

You can change the setter method of the variable to check for 0 and set NULL.

public Integer index { 
    get;
    set{
        index = (index == 0) ? NULL : value;
    }
}

One problem here is, if you try to assign the value 0, then it nullifies it.

@crmprogdev suggestion of making the variable static doesn't seem to work for me.

@adrianlarson's answer is quite apt if you are trying to set null always.

Answer 4

I ended up with Boolean variable.

On VF page:

<apex:inputHidden value="{!isActualHoursBlank}" id="actualHoursInputHidden"/>

<apex:actionSupport event="onclick" action="{!saveProduct}" 
  immediate="false"
  onsubmit="onSumbmitProductSave('{!$Component.actualHoursInput}', {!$Component.actualHoursInputHidden}');">

<script>
  function onSumbmitProductSave(actualHoursInputId, actualHoursInputHiddenId) {
    var actualHoursInputEl = document.getElementById(actualHoursInputId);
    var actualHoursInputHiddenEl = document.getElementById(actualHoursInputHiddenId);
    if (actualHoursInputEl.value == '' || actualHoursInputEl.value == null) {
      actualHoursInputHiddenEl.value = true;
    } else {
      actualHoursInputHiddenEl.value = false;
    }
  }
</script>

And in Controller I set Object's field as null in case isActualHoursBlank is set to true.