Grails：如何以编程方式将命令对象数据绑定到服务中的域对象？

Question

I have a command object that I want to convert into a domain object.

However, the object I want to convert the command object into may be one of two domain classes (they're both derived classes), and I need to do it in a service (which is where, based on other data, I decide which type of object it should be bound to). Is this possible and what's the best way to do this? bindData() only exists in a controller.

Do I just have to manually map command object parameters to the appropriate domain object properties? Or is there a faster/better way?

Answer 1

If the parameters have the same name, then you can use this question to copy the values over. A quick summary can be as follows.

Using the Grails API

You can cycle through the properties in a class by accessing the properties field in the class.

object.properties.each { property -> 
    // Do something
}

You can then check to see if the property is present in the other object.

if(otherObject.hasProperty(property) && !(key in ['class', 'metaClass']))

Then you can copy it from one object to the other.

Using Commons

Spring has a really good utility class called BeanUtils that provides a generic copy method that means you can do a simlple oneliner.

BeanUtils.copyProperties(object, otherObject);

That will copy values over where the name is the same. You can check out the docs here .

Otherwise..

If there is no mapping between them, then you're kind of stuck because the engine has no idea how to compare them, so you'll need to do it manually.