Been looking for a way to update an apex:page content type but don't see any source about it AHAHA. I have this ATM:
<apex:page standardController="sObject" extensions="<apexClass>"
</apex:page>
the apex class in the extension has a lot of functionalities and i have an href in the middle of the page that is linked to a template which when clicked can be viewed and saved as a CSV file.
but instead of viewing a template, I wanted to upgrade the functionality into a downloadable one. So i want to find a way to update the header that when the link gets clicked it adds this contenttype="application/vnd.ms-excel
to the header of the apex:page.
you guys have an idea if there's such a thing in VF?
Yes, you can put expressions in pretty much any Visualforce parameter including apex:page
's contentType
. Something like this:
<apex:page lightningstylesheets="true" standardController="Contact" recordSetVar="contacts" extensions="SomeClass"
showHeader="{!showForm}" sidebar="{!showForm}" applyHtmlTag="{!showForm}" standardStylesheets="{!showForm}"
id="p" contentType="{!IF(showForm, 'text/html', 'application/vnd.ms-excel#Contactss.xls')}" readonly="true">
<apex:outputPanel layout="none" rendered="{!showForm}">
<apex:form >
<apex:pageBlock>
<apex:pageBlockButtons location="top">
<apex:actionStatus id="status">
<apex:facet name="stop">
<apex:outputPanel >
<apex:commandButton value="{!$Label.preview}" action="{!preview}" rerender="controls,preview" status="status"/>
<apex:commandButton value="{!$Label.export}" action="{!export}" status="status"/>
<apex:commandButton value="{!$Label.cancel}" action="{!cancel}" immediate="true" />
</apex:outputPanel>
</apex:facet>
<apex:facet name="start">
<apex:outputPanel >
<apex:commandButton value="{!$Label.preview}" disabled="true"/>
<apex:commandButton value="{!$Label.export}" disabled="true"/>
<apex:commandButton value="{!$Label.cancel}" action="{!cancel}" immediate="true" />
<img id="status" src="/img/loading.gif" alt="Loading..." title="Loading..."/>
</apex:outputPanel>
</apex:facet>
</apex:actionStatus>
</apex:pageBlockButtons>
<apex:pageBlockSection columns="1" id="controls">
put some form here, input fields...
</apex:pageBlockSection>
</apex:pageBlock>
<apex:pageBlock title="Preview" id="preview">
optionally display first 10 rows or something
</apex:pageBlock>
</apex:form>
</apex:outputPanel>
<apex:outputPanel id="o" layout="none" rendered="{!!showForm}">
{!csv} Payload here
</apex:outputPanel>
</apex:page>
But be sure to check how it behaves in Lightning Experience (if you use it). Last time I played with it there was some extra output in LEX and eventually I cheated. I output CSV to hiddent html element, grab it with JavaScript.
<apex:commandButton value="{!$Label.export}" action="{!downloadCsv}" rerender="out" oncomplete="javascript:downloadComplete();return false;" status="status"/>
...
<apex:outputPanel id="out" style="display:none">
<span class="payload">{!csvBody}</span>
<script>
function downloadComplete(){
let payload = document.getElementsByClassName('payload')[0].innerText.replaceAll('<br/>', '\n');
let filename = 'Equipment Utilization Report.csv';
let link = document.createElement('a');
link.href = 'data:text/csv;charset=utf-8,' + encodeURIComponent(payload);
link.target = '_self';
link.download = filename;
link.click();
return false;
}
</script>
</apex:outputPanel>