渲染视图，但 gsp 中没有对象

Question

我尝试渲染一个视图，效果很好，但它似乎没有得到我传递给它的模型对象。我无法弄清楚原因，因为根据所有手册和示例，这应该是非常简单的。

模型对象

class Race {

    def distance = "1/4 mile"
    def racer1
    def racer2
}

RaceController 在此处呈现

def doFullRace(Race race) {

            render (view: 'raceProgress', model: [race: race])
        }

和raceProgress.gsp应该很容易显示它

    <html>
    <body>
        <div id="raceStart" align="center">
...
            <p>${race.racer1} is racing ${race.distance} against ${race.racer2}</p>
        </div>
    </body>
    </html>

但我反而明白了

关于我错过了什么基本的事情有什么想法吗？

Answer 1

您有以下内容：

def doFullRace(Race race) {
    render (view: 'raceProgress', model: [race: race])
}

race 成为 null 的方法之一是，如果以下所有条件都为真：

Race 是一个域 class
提交给 doFullRace 的请求包含一个名为 id
数据库中没有 id 匹配 params.id

从http://docs.grails.org/3.3.9/guide/theWebLayer.html#commandObjects...

If the command object’s type is that of a domain class and there is an id request parameter then instead of invoking the domain class constructor to create a new instance a call will be made to the static get method on the domain class and the value of the id parameter will be passed as an argument.

还有...

If the command object’s type is a domain class and there is no id request parameter or there is an id request parameter and its value is empty then null will be passed into the controller action unless the HTTP request method is "POST", in which case a new instance of the domain class will be created by invoking the domain class constructor. For all of the cases where the domain class instance is non-null, data binding is only performed if the HTTP request method is "POST", "PUT" or "PATCH".

渲染视图，但 gsp 中没有对象

Rendering view, but no object in gsp

grails

render

gsp