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I have the below VF Page where I am using pagination to only show 7 records at a time: enter image description here

The VF component code in the VF page is:

<apex:pageBlock id="navGroup" rendered="true" >
<div align="center">        
    <apex:actionFunction action="{!refreshGrid}" name="queryByPage" reRender="navGroup,myButtons" >
        <apex:param name="firstParam" assignTo="{!selectedPage}" value="" />
    </apex:actionFunction>      
    <apex:dynamicComponent componentValue="{!navButtons}"/>                 
    </div>
    <br/>

and the APEX code in my controller that creates the buttons is:

public Component.Apex.outputPanel getnavButtons() {

    //the reRender attribute is a set NOT a string
    Set<string> theSet = new Set<string>();
    theSet.add('navGroup');
    theSet.add('myButtons');

    integer totalPages;
    if (math.mod(total_size, list_size) > 0) {
        totalPages = total_size/list_size + 1;
    } else {
        totalPages = (total_size/list_size);
    }

    integer currentPage;        
    if (selectedPage == '0') {
        currentPage = counter/list_size + 1;
    } else {
        currentPage = integer.valueOf(selectedPage);
    }

    Component.Apex.outputPanel opPanel = new Component.Apex.outputPanel();
    opPanel.id = 'myButtons';

    Component.Apex.OutputText htmlPrevTxtStart = new Component.Apex.OutputText(); 
    htmlPrevTxtStart.value = '<div class="block-link" disabled="{!disablePrevious}" id="PrevButton" onmouseover="ButtonMouseOver(\'PrevButton\');" onmouseout="ButtonMouseOut(\'PrevButton\');" >';     
    htmlPrevTxtStart.escape = false;  

    Component.Apex.CommandLink pbLinkPrev = new Component.Apex.CommandLink ();     
    pbLinkPrev.style='color: rgb(255,255,255)';
    pbLinkPrev.expressions.action = '{!Previous}';
    //pbLinkPrev.expressions.disabled = '{!disablePrevious}';  
    pbLinkPrev.value='Previous';
    pbLinkPrev.id = 'mynewButtonsPrev';

    Component.Apex.OutputText htmlPrevTxtEnd = new Component.Apex.OutputText(); 
    htmlPrevTxtEnd.value = '</div>';        
    htmlPrevTxtEnd.escape = false;         

    opPanel.childComponents.add(htmlPrevTxtStart);
    opPanel.childComponents.add(pbLinkPrev);
    opPanel.childComponents.add(htmlPrevTxtEnd);        
        // 
    Component.Apex.OutputText htmlNextTxtStart = new Component.Apex.OutputText(); 
    htmlNextTxtStart.value = '<div class="block-link" disabled="{!disablePrevious}" id="nextButton" onmouseover="ButtonMouseOver(\'nextButton\');" onmouseout="ButtonMouseOut(\'nextButton\');" >';     
    htmlNextTxtStart.escape = false; 

    Component.Apex.CommandLink pbLinkNext = new Component.Apex.CommandLink ();     
    pbLinkNext.style='color: rgb(255,255,255)';
    pbLinkNext.expressions.action = '{!Next}';
    pbLinkNext.value='Next';
    //pbLinkNext.expressions.disabled='{!disableNext}';
    pbLinkNext.id = 'mynewButtonsNext';

    Component.Apex.OutputText htmlNextTxtEnd = new Component.Apex.OutputText(); 
    htmlNextTxtEnd.value = '</div>';        
    htmlNextTxtEnd.escape = false; 

    opPanel.childComponents.add(htmlNextTxtStart);
    opPanel.childComponents.add(pbLinkNext);
    opPanel.childComponents.add(htmlNextTxtEnd);

    return opPanel;

}    

public PageReference refreshGrid() { //user clicked a page number        
    system.debug('**** ' + selectedPage);
    return null;
}

public PageReference Previous() { //user clicked previous button
    selectedPage = '0';
    counter -= list_size;
    return null;
}

public PageReference Next() { //user clicked next button
    selectedPage = '0';
    counter += list_size;
    return null;
}

public PageReference End() { //user clicked end
    selectedPage = '0';
    counter = total_size - math.mod(total_size, list_size);
    return null;
}

public Boolean getDisablePrevious() { //this will disable the previous and beginning buttons
    if (counter>0) return false; else return true;
}

public Boolean getDisableNext() { //this will disable the next and end buttons
    if (counter + list_size < total_size) return false; else return true;
}

public Integer getTotal_size() {
    return total_size;
}

public Integer getPageNumber() {
    return counter/list_size + 1;
}

public Integer getTotalPages() {
    if (math.mod(total_size, list_size) > 0) {
        return total_size/list_size + 1;
    } else {
        return (total_size/list_size);
    }
}

the data is paged using offset and limit in the SOQL query that returns the list for my table.

The problem I am having is that if I click the Prev button when it's already at the beginning of the dataset I get an SOQL error...

So how can I disable or hide the Prev button when it's on the first page, and disable or hide the Next button when it's reached the end of the dataset?

3

You need to split your Previous/Next navigation into uniquely addressable elements rather than grouping them together, and, ideally, use an <apex:outputPanel> or <apex:pageBlock> or even <apex:commandButton> or some other VF element that is not a vanilla <div>. Then, you can expose your existing currentPage accessor and replace your

<apex:pageBlock id="navGroup" rendered="true" >

with something more like

  • <apex: ... rendered="{!currentPage > 0}"> for your Previous button, and
  • <apex: ... rendered="{!currentPage < numPages}"> for your Next button.

Then, each time a navigation button is clicked, fetch the next or previous batch of records and rerender your navigation elements.

  • I didn't do it that way in the end, but thanks for pointing me in the right direction – Our Man in Bananas Feb 8 '16 at 19:21
  • I asked another question, showing how I solved this problem here – Our Man in Bananas Feb 8 '16 at 19:27

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