<apex:page controller="DynamicPdf" renderAs="{!pageFormat}" standardStylesheets="false">
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<apex:form >
<apex:commandButton action="{!go}" value="Go"/>
</apex:form>
</apex:page>
public class DynamicPdf {
String pageFormat;
public PageReference go() {
pageFormat = 'pdf';
return Page.DynamicPdf;
}
public String getPageFormat() {
return pageFormat;
}
}
Try this page and controller: