In Soy (Closure) templates, how can I print an expression that might be undefined at runtime?

Question

Let's say the template model contains a map called $myMap whose keys are unknown at compile time. If my template attempts to print a map entry using {$myMap[$someValidKey]} , all is fine. However if I try to print using {$myMap[$someInvalidKey]} , the template fails to render and instead throws this error:

In 'print' tag, expression "$myMap[$someInvalidKey]" evaluates to undefined.

How can I tell the template to simply print nothing if that expression is undefined, ie no such key exists in the map?

Answer 1

我刚刚确认您可以有条件地包装它：

{if $myMap[$someInvalidKey]}{$myMap[$someInvalidKey]}{/if}

Answer 2

在未定义的情况下，可以使用{$myMap[$someInvalidKey] ?: ''}返回到不打印任何内容（空字符串）。