Grails选择不设置默认值

Question

我有一个应用程序，用户可以填写表格，并保存一些预设，以便快速重新填充

class Person {
    String name
    TeenageMutantNinjaTurtle favorite
    static constraints = {
        name blank:false, unique:true
        favorite nullable:true
    }
    @Override
    public String toString() { name }
}
    package tmnt
class TeenageMutantNinjaTurtle {
    String name
    String colorHeadband
    static constraints = {
        name inList:["Leonardo", "Donatello", "Raphael", "Michelangelo"]
        colorHeadband inList:["blue", "purple", "red", "orange" ]
    }
    @Override
    public String toString() { "${name}" }
}

控制器

class PersonController {

 def choose = {
    if(session.user) {
        def person = Person.findByName(session.user.username)
        [
         teenageMutantNinjaTurtleInstanceList: TeenageMutantNinjaTurtle.list(), 
         person : person, 
         favorite : person.favorite
        ]
    }
}
def pickFavoriteTurtle = { TurtleCommandObject tut ->
    def turtle = tut.turtleName
    def choice = TeenageMutantNinjaTurtle.findByName(turtle)
    String message = "Turtle not chosen "
    if(choice){
        def person = Person.findByName(tut.personName)
        person.favorite = choice
        person.save()
        message = "Made ${person}'s favorite turtle ${choice}"
    }
    else {
        message += "could not find ${choice}"
    }
    render message
 }

<<p> 视图/strong>

        <div>
          <h1>Hello ${person} </h1>
            <g:form action="pickFavoriteTurtle">
                <g:hiddenField name="personName" value="${person}" />
                <g:select name="turtleName" from="${teenageMutantNinjaTurtleInstanceList}" value="${favorite}" />
                <g:submitToRemote  name="pickFavoriteTurtle" 
                                   url="[action:'pickFavoriteTurtle']"  
                                   value="Save your favorite turtle" />
            </g:form>
        </div>

收藏夹永远不会成为最初选择的值，即使我可以像用户指南中描述的那样证明它的计算结果等于true。到底发生了什么事?

Answer 1

Tomas Lin在Grails邮件列表上的回答:

如果你坚持使用id，你的生活会更容易。

设置optionKey等于标签中对象的id。

value = '${favorite. 'Id}'现在可以工作了。

Answer 2

几件事

1. 如果favorite是一个有id的对象，你需要value = " $ {favorite.id} "
2. 你可以直接使用value="${person.favorite.id}"