A mistake made about foreach traversal

I encountered such an exception today:


Serious: Servlet.service() for servlet jsp threw exception

javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in <forEach>

According to the abnormal prompt information, we know that the corresponding collection cannot be traversed. Why? I debugged it and reported an error as soon as I got to the page. The problem was on the page. I looked back and found that it was not a collection but an object. I didn't notice this! After adjustment, it can be used directly (passing a collection for traversal can be used directly).

If an object is taken from another page and directly use EL expression to drop its properties, you can no longer traverse