看起来并不那么简单。 :)如果运行此命令，我们可以得到一个生动的图片：

  grails url-mapping-report 
 code> 

查看

 控制器：公制
 | GET | / api / sensors / $ {sensorId} / metrics |操作：index | 
 | GET | / api / sensors / $ {sensorId} / metrics / create |操作：创建| 
 | POST | / api / sensors / $ {sensorId} / metrics |操作：保存| 
 | GET | / api / sensors / $ {sensorId} / metrics / $ {id} |操作：show | 
 | GET | / API /传感器/ $ {} sensorId /度/ $ {ID} /编辑|操作：编辑| 
 | PUT | / api / sensors / $ {sensorId} / metrics / $ {id} |行动：更新| 
 |删除| / api / sensors / $ {sensorId} / metrics / $ {id} |操作：删除| 
 

所以，我们至少需要一个 MetricController 继承 RestfulController 并覆盖 index（）来对 Metric 和基于传感器的返回列表，如下所示：

  class MetricController extends RestfulController< Metric> {
 static responseFormats = ['json'，'xml'] 

 MetricController（）{
 super（公制）
} 

 @Override 
 def index（）{
 def sensorId = params.sensorId 
响应Metric.where {
 sensor.id == sensorId 
} .list（）






上面的变化会提供预期的结果（包括限制分页结果）为 / api / sensors / 1 / metrics 命中。 
I'm using the support for REST introduced by Grails in 2.3. My app includes the following domain classes:
@Resource(formats=['json', 'xml'])
class Sensor {
    String name
    static hasMany = [metrics: Metric]
}

@Resource(formats=['json', 'xml'])
class Metric {

    String name
    String value

    static belongsTo = [sensor: Sensor]
}

And in UrlMappings.groovy I've defined the following nested RESTful URL mappings:
"/api/sensors"(resources: 'sensor') {
    "/metrics"(resources: "metric")
}

If I navigate to the URL /api/sensors/1/metrics I expect the response to show all Metric instances associated with the Sensor with ID 1, but in fact it returns all Metric instances (up to a limit of 10)


Is there a URL that will return only Metric instances associated with a particular Sensor instance (without implementing my own controller)?
Is there a way to override the default limit of 10 results (without adding a max parameter to the request)?


Looks like it isn't that simple. :) We can get a vivid picture if this command is run:
grails url-mapping-report

to see
Controller: metric
 |   GET    | /api/sensors/${sensorId}/metrics           | Action: index  |
 |   GET    | /api/sensors/${sensorId}/metrics/create    | Action: create |
 |   POST   | /api/sensors/${sensorId}/metrics           | Action: save   |
 |   GET    | /api/sensors/${sensorId}/metrics/${id}     | Action: show   |
 |   GET    | /api/sensors/${sensorId}/metrics/${id}/edit| Action: edit   |
 |   PUT    | /api/sensors/${sensorId}/metrics/${id}     | Action: update |
 |  DELETE  | /api/sensors/${sensorId}/metrics/${id}     | Action: delete |

So, we would at least need a MetricController inheriting RestfulController and override index() to do an additional check for Metric and return list based on Sensor as shown below:
class MetricController extends RestfulController<Metric> {
    static responseFormats = ['json', 'xml']

    MetricController() {
        super(Metric)
    }

    @Override
    def index() {
        def sensorId = params.sensorId
        respond Metric.where {
            sensor.id == sensorId
        }.list()
    }
}

Above changed would provide the expected result (including the restriction on paginated results) for /api/sensors/1/metrics when hit.