Required Field InfoPath

Can you can make an info path attachment control mandatory based on a set criteria?

if listbox selected value is High 
    attachment is mandatory 
else 
    not mandatory .

this form will be in sharepoint as 开发者_JAVA百科a web based form

No you can't change the build in mandatory support on the fly because it depends on the xsd schema

But you can just make your field not mandatory and then add a data validation which doesn't allow the field to be blank if listbox is High