读取速度模板中映射的模型对象 [英] Reading model objects mapped in Velocity Templates

问题描述

我有一个 Struts + Velocity 结构，例如一个 Person 类，它的一个属性是一个 Car 对象(具有自己的 getter/setter 方法)，并且它被映射到一个 Velocity 表单，该表单使用 ModelDriven 提交给一个 Action和 getModel 结构.

I have a Struts + Velocity structure like for example, a Person class, whose one property is a Car object (with its own getter/setter methods) and it is mapped to a Velocity form that submits to an Action, using ModelDriven and getModel structure.

如果 car 属性不为 null 或 car.id != 0，我应该在表单上放置一个按钮，显示查看汽车"，或者如果汽车为 null 或 car.id = 0，则显示另一个按钮选择汽车".

I what to put a button on the form that shows "View Car" if car property is not null or car.id != 0 or show another button "Choose Car" if car is null or car.id = 0.

我该如何编码.我在模板文件中尝试了类似的东西:

How do I code this. I tried something like that in the template file:

#if($car != null)
  #ssubmit("name=view" "value=View Car")
#else
  #ssubmit("name=new" "value=Choose Car")
#end

但我一直在 #if 行中收到有关 Null 值的错误.

But I keep getting error about Null value in the #if line.

我还在 Person 中创建了一个布尔方法 hasCar() 来尝试，但我无法访问它，也不知道为什么.

I also created a boolean method hasCar() in Person to try, but I can't access it and I don't know why.

而且 Velocity + Struts 教程很难找到或有很好的信息.

And Velocity + Struts tutorials are difficult to find or have good information.

谢谢

推荐答案

您应该将 #if 行更改为:

You should change the #if line to:

#if($car)

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