一个velocity的#set指令赋值null的坑

发布于:2021-06-11 10:51:54

#set($price = $item.sku.price)
如果在一个两次循环里 item.sku.price第一次是5.0,第二次是null,那么$price的值为两个5.0,因为默认情况下给velocity变量使用#set指令赋值时,如果等式右边为null,那么不会解除等式左边变量的引用。



If the RHS is a property or method reference that evaluates to null, it will not be assigned to the LHS. Depending on how Velocity is configured, it is usually not possible to remove an existing reference from the context via this mechanism. (Note that this can be permitted by changing one of the Velocity configuration properties).



解决办法:
1. 不用#set指令,直接一串点点点(item.sku.price)输出值
2. 在velocity配置文件中配置 directive.set.null.allowed = true

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