在Spring Controller方法中将ModelAttribute设为可选 [英] Making ModelAttribute optional in Spring Controller method

问题描述

我有一个定义如下的控制器方法-

I have a controller method defined as follows -

@RequestMapping(method = RequestMethod.POST, value="/callMe")
public String myMethod(@ModelAttribute MyClass myObj, Model model) {
    //Do something
}

即使我没有传递ModelAttribute myObj，也如何才能调用上述控制器方法.

How can I make the above controller method to be called even when I do not passed the ModelAttribute myObj.

我不想在没有它的情况下创建另一个控制器并复制功能.

I do not want to create another controller without it and duplicate the functionality.

推荐答案

Model属性已经是可选的.即使您不传递模型属性，也会创建myObj.所以检查

Model attribute is already optional. Even if you do not pass model attribute, myObj is created. So checking

if(myObj == null){
   //Do method1
}else{
  //Do method2
}

不起作用.

尝试一下.像这样在myClass中创建一个布尔值

Try this. create a Boolean in myClass like this

private Boolean isGotMyObj = false;

在您的jsp(提交模型属性)中添加这样的隐藏输入

In your jsp which (submits model attribute) add a hidden input like this

<input type="hidden" value="1" name="isGotMyObj" />

然后在控制器中执行此操作

then perform this in controller

@RequestMapping(method = RequestMethod.POST, value="/callMe")
public String myMethod(@ModelAttribute MyClass myObj, Model model) {
    if (myObj.getIsGotMyObj()){
        //Got model attribute
        //Method 1
    }else{
        //Method 2
    }

    return "callme";
}

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