Grails 数据绑定 - 带有列表的命令对象 [英] Grails data binding - command objects with Lists

问题描述

Grails 1.3.7

Grails 1.3.7

具有 List 内容的数据绑定 Command 对象有问题.示例命令:

Trouble with data binding Command objects that have List content. Example Command:

class Tracker {
    String name
    String description
    List<Unit> units = new ArrayList()
}

class Unit {
    String name
    Long unitMax
    Long unitMin
}

为跟踪器创建 GSP 具有单位字段.一个例子:

create GSP for Tracker has the Unit fields. One example:

<g:textField name="units[0].unitMax" value=""/>

TrackerController 保存方法:

TrackerController save method:

 def save = { Tracker trackerInstance ->
   trackerInstance = trackingService.saveOrUpdateTracker(trackerInstance)
 }

但是，总是 java.lang.IndexOutOfBoundsException

But, always java.lang.IndexOutOfBoundsException

或者，如果我将控制器更新为:

Alternatively, if I update controller to:

def save = {
   Tracker trackerInstance = new Tracker()
   trackerInstance.properties = params
   ....

然后 groovy.lang.ReadOnlyPropertyException:无法设置只读属性:类的属性:com.redbrickhealth.dto.Tracker有任何想法吗?

Then groovy.lang.ReadOnlyPropertyException: Cannot set readonly property: properties for class: com.redbrickhealth.dto.Tracker Any ideas?

GORM 和 Command 对象中的绑定之间似乎存在差异.

There seems to be a difference between binding in GORM vs Command objects.

也许我需要为 Unit 扩展和注册一个 PropertyEditorSupport?

Maybe I need to extend and register a PropertyEditorSupport for Unit?

-托德

推荐答案

Grails 需要一个具有现有列表的命令，该命令将填充来自请求的数据.

Grails requires an command with existing list, that will be filled with data from reques.

如果您知道确切的单位数，例如 3，您可以:

If you know exact number of units, say 3, you can:

class Tracker {
    String name
    String description
    List<Unit> units = [new Unit(), new Unit(), new Unit()]
}

或使用 apache 公共集合中的 LazyList

or use LazyList from apache commons collections

import org.apache.commons.collections.ListUtils
import org.apache.commons.collections.Factory
class Tracker {
    String name
    String description
    List<Unit> units = ListUtils.lazyList([], {new Unit()} as Factory)
}

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