[SalesForce] Why does apex:param assignTo work with apex:commandLink but not apex:commandButton

How do command buttons and command links differ when it comes to using <apex:param>?
The param value is not being passed to the controller.

I have the following code in a Controller :

public pagereference Pageredirect_new(){
     currentpageId = Apexpages.currentpage().getparameters().get('id');
    redirectUrl = new pagereference('/a2A/e?CF00NK0000000cZqA='+account_name+'&CF00NK0000000cZqA_lkid='+currentpageId);
    return redirectUrl ;
    }

  <apex:commandLink value="New" action="{!Pageredirect_new}">
           <apex:param assignTo="{!account_name}" value="{!Account.name}" name="account_name"/>
           </apex:commandLink>

I get the resulting URL as :

/a2A/e?CF00NK0000000cZqA=donotshow......

When I do

<apex:commandButton value="New" action="{!Pageredirect_new}">
               <apex:param assignTo="{!account_name}" value="{!Account.name}" name="account_name"/>
               </apex:commandButton>

The resulting URL : a2A/e?CF00NK0000000cZqA=null....

Am I missing something?

Best Answer

It's something that's perceived as a "known bug" by the dev community but it never made to the list...

Jeff Douglas has written this up together with viable workarounds in March 2010: http://blog.jeffdouglas.com/2010/03/04/passing-parameters-with-a-commandbutton/ (the post and comments also contain few useful links to SF message boards).

Simple fix is to use commandLink but style it to look like a button:

<apex:commandLink action="{!Pageredirect_new}" value="New" styleClass="btn" style="color:white;text-decoration:none">
    <apex:param assignTo="{!account_name}" value="{!Account.name}" name="account_name"/>
</apex:commandLink>

Or (ab)use the fact that commandButton suddenly behaves as it should if one of it's side-effects will be a rerender of something (even of a region you don't care about).

<apex:commandButton action="{!Pageredirect_new}" value="New" rerender="hiddenBlock">
    <apex:param assignTo="{!account_name}" value="{!Account.name}" name="account_name"/>
</apex:commandButton>

<apex:pageBlock id="hiddenBlock" rendered="false"></apex:pageBlock>

Last but not least, allow me to chip in my usual rant ;) Do you realize that you don't need an action method in your controller at all? Well, unless you have greatly simplified the code...

<apex:commandLink action="/a2A/e?CF00NK0000000cZqA={!Account.name}&CF00NK0000000cZqA_lkid={!$CurrentPage.parameters.id}" value="New" />

In fact you could go even further, if you'll realize you need immediate="true" in this link then you might be better of with plain old <a> tag...

If you'll keep such links in VF and not Apex they're much easier to modify later on (new fields, forgotten URLENCODE'ing etc) plus that's always couple lines less to cover with unit test ;)

Related Solutions

[SalesForce] Disable commandButton after first click to prevent double submission

The mechanism I have found to be most maintainable uses a JavaScript function called by an element's click event, which internally calls an actionFunction to post the form, disables the buttons on the page and then returns false on the commandlink/button. This is used in conjunction with an oncomplete on the actionFunction to re-enable the buttons when the form has been (ajax) posted and returns a result to the page.

Without the rerender attribute the form performs a full postback along with the disabling of the buttons.

Note: You can't disable the button(s) before the form is posted or the data sent to the controller will not include which button/link within the form was clicked and thus which action to execute.

<script src="//ajax.googleapis.com/ajax/libs/jquery/latest/jquery.js"></script>
<script>

    function buttonsEnabled(enabled) {
        // retrieve all of the buttons or links on the page
        // with the css class of btn
        var $buttons = jQuery('.btn');
        if (enabled === false) {
            // add the btnDisabled class to give it the look of being disabled
            // add the disabled attribute to actually disable interactability
            $buttons.toggleClass('btnDisabled', true).attr('disabled', 'disabled');
        } else {
            // remove the css class and the disabled attribute
            $buttons.toggleClass('btnDisabled', false).attr('disabled', null);
        } 
    }

    function doSomeWork() {
        // first, call the action function to post the form
        doSomeWorkActionFunction();

        // second, disable the buttons
        buttonsEnabled(false);

        // third, return false to prevent the click from
        // posting the form a second time
        return false;
    }

</script>

<apex:form>

    <apex:actionFunction name="doSomeWorkActionFunction" 
        action="{!yourControllerMethod}" 
        oncomplete="buttonsEnabled(true);"
        rerender="whateverYouNeedToRerender"></apex:actionFunction>

    <apex:commandLink action="{!yourControllerMethod}" 
        value="Your Text Here" 
        id="theCommandLink" 
        onclick="return doSomeWork();" />

</apex:form>

[SalesForce] ActionFunction working in Chrome but not in IE and Moz

Try to use jQuery to trigger on the keyPress/keyDown events. Additionally i leave the value parameter empty if i want to set it from another javascript function and use reRender to refresh some areas:

<script>
jQuery('[id$=myField]').on('keydown keypress keyup', function(event) {
    if (event.keyCode == 13) {
        event.preventDefault();
        insertOffer(jQuery(this).val());
    }
});
</script>


<apex:actionFunction name="insertOffer" action="{!setNewBidOffer}" reRender="myField">
     <apex:param name="currOffer" value="" assignTo="{!currentOffer}"/>
</apex:actionFunction>

<apex:inputText value="{!currentOffer}" id="myField"/>

But one thing i don't understand: you trying to set the currentOffer variable to the currentOffer variable?

Best Answer

Related Solutions

[SalesForce] Disable commandButton after first click to prevent double submission

[SalesForce] ActionFunction working in Chrome but not in IE and Moz

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