Passing Parameters Commandbutton

Question

I don't know what is wrong with the code, I read a lot about the commandbutton and param, but it doesn't work.

The Debug shows me that the value of the MS_Item is Null. 07:44:00.0 (8771917)|USER_DEBUG|[8]|DEBUG|my MS_Item: null

PAGE:

<apex:page controller="clicktest">

    <apex:form>

    <apex:commandButton action="{!Stats_In}" value="click" reRender="">
        <apex:param name="MS_Item" value="MS_Item_45382" assignTo="{!MS_Item}" />
    </apex:commandButton>

    </apex:form>    

</apex:page>

CLASS:

public class clicktest {

    Public String MS_Item {get; set;}

    public PageReference Stats_In() {
        MedienServer_Stats__c sta = new MedienServer_Stats__c();
        sta.MS_Item__c = MS_Item;    
        System.debug('my MS_Item: ' +MS_Item);
        INSERT sta;
        RETURN NULL;
    }

}

Answer 1

Need to be add a DummyID for reRedner.

<apex:page controller="clicktest">
    <apex:form>
    <apex:commandButton action="{!Stats_In}" value="click" reRender="dummyId">
        <apex:param name="MS_Item" value="MS_Item_45382" assignTo="{!MS_Item}" />
    </apex:commandButton>
    </apex:form>    
</apex:page>

Answer 2

Just add a dummy panel and reRender it. It will work.

<apex:outputPanel id="panel2">

</apex:outputPanel>

<apex:commandButton action="{!Stats_In}" value="click" reRender="panel2">
    <apex:param name="MS_Item" value="MS_Item_45382" assignTo="{!MS_Item}" />
</apex:commandButton>