如何从对象的外键中获取对象的值？
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【中文标题】如何从对象的外键中获取对象的值？【英文标题】：How to get a value of a object from its foreign key? 【发布时间】：2016-03-29 00:52:22 【问题描述】：我正在使用 Backand 来存储我的数据。我有一个对象，事件，它引用另一个对象，位置。
"name": "events",
"fields":
"eventCommentsId":
"collection": "comments",
"via": "eventId"
,
"tags":
"collection": "events_tags",
"via": "event"
,
"users":
"collection": "users_events",
"via": "event"
,
"name":
"type": "string"
,
"date":
"type": "datetime"
,
"time":
"type": "datetime"
,
"info":
"type": "text"
,
"locationId":
"object": "locations"
,
"name": "locations",
"fields":
"events":
"collection": "events",
"via": "locationId"
,
"name":
"type": "text"
,
"geo":
"type": "point"
当我尝试显示事件的位置时，我只能获取 locationID 的值。我想要位置的实际名称，而不是 id。我该怎么做？
<ion-list>
<ion-item class="item item-thumbnail-left" ng-repeat="event in events" type="item-text-wrap" href="#/event-detail/event.id">
<h2>event.name</h2>
<p><i class="ion-location"></i> event.locationId.name</p>
<ion-option-button class="button-assertive" ng-click="deleteEvent(event.id)">
Delete
</ion-option-button>
</ion-item>
</ion-list>
角码
.service('EventService', function ($http, Backand)
var baseUrl = '/1/objects/';
var objectName = 'events/';
function getUrl()
return Backand.getApiUrl() + baseUrl + objectName;
function getUrlForId(id)
return getUrl() + id;
getEvents = function ()
return $http.get(getUrl());
;
addEvent = function(event)
return $http.post(getUrl(), event);
deleteEvent = function (id)
return $http.delete(getUrlForId(id));
;
getEvent = function (id)
return $http.get(getUrlForId(id));
;
return
getEvents: getEvents,
addEvent: addEvent,
deleteEvent: deleteEvent,
getEvent: getEvent
)
.controller('FeedCtrl', ['$scope', '$ionicModal', '$ionicSideMenuDelegate', 'EventService', function($scope, $ionicModal, $ionicSideMenuDelegate, EventService)
$scope.events = [];
$scope.input = ;
function getAllEvents()
EventService.getEvents()
.then(function (result)
$scope.events = result.data.data;
);
$scope.addEvent = function()
EventService.addEvent($scope.input)
.then(function(result)
$scope.input = ;
getAllEvents();
);
$scope.deleteEvent = function(id)
EventService.deleteEvent(id)
.then(function (result)
getAllEvents();
);
getAllEvents();
])
【问题讨论】：
【参考方案1】：有两种选择。您可以使用每个对象的 __metadata 中的描述性值，如下所示： 请求：https://api.backand.com/1/objects/events?pageSize=20&pageNumber=1
回复：
"totalRows": 2,
"data": [
"__metadata":
"id": "1",
"fields":
"id":
"type": "int",
"unique": true
,
"name":
"type": "string"
,
"date":
"type": "datetime"
,
"time":
"type": "datetime"
,
"info":
"type": "text"
,
"locationId":
"object": "locations"
,
"descriptives":
"locationId":
"label": "Madison Square Garden",
"value": "1"
,
"dates":
"date": "",
"time": ""
,
"id": 1,
"name": "knicks vs warriors",
"date": null,
"time": null,
"info": "",
"locationId": "1"
,
"__metadata":
"id": "2",
"fields":
"id":
"type": "int",
"unique": true
,
"name":
"type": "string"
,
"date":
"type": "datetime"
,
"time":
"type": "datetime"
,
"info":
"type": "text"
,
"locationId":
"object": "locations"
,
"descriptives":
"locationId":
"label": "Madison Square Garden",
"value": "1"
,
"dates":
"date": "",
"time": ""
,
"id": 2,
"name": "knicks vs cavs",
"date": null,
"time": null,
"info": "",
"locationId": "1"
]
或者你可以做一个深度请求并获取相关对象中的值 请求：https://api.backand.com/1/objects/events?pageSize=20&pageNumber=1&deep=true
回复：
"totalRows": 2,
"data": [
"__metadata":
"id": "1",
"fields":
"id":
"type": "int",
"unique": true
,
"name":
"type": "string"
,
"date":
"type": "datetime"
,
"time":
"type": "datetime"
,
"info":
"type": "text"
,
"locationId":
"object": "locations"
,
"descriptives":
"locationId":
"label": "Madison Square Garden",
"value": "1"
,
"dates":
"date": "",
"time": ""
,
"id": 1,
"name": "knicks vs warriors",
"date": null,
"time": null,
"info": "",
"locationId": "1"
,
"__metadata":
"id": "2",
"fields":
"id":
"type": "int",
"unique": true
,
"name":
"type": "string"
,
"date":
"type": "datetime"
,
"time":
"type": "datetime"
,
"info":
"type": "text"
,
"locationId":
"object": "locations"
,
"descriptives":
"locationId":
"label": "Madison Square Garden",
"value": "1"
,
"dates":
"date": "",
"time": ""
,
"id": 2,
"name": "knicks vs cavs",
"date": null,
"time": null,
"info": "",
"locationId": "1"
],
"relatedObjects":
"locations":
"1":
"__metadata":
"id": "1",
"fields":
"id":
"type": "int",
"unique": true
,
"events":
"collection": "events",
"via": "locationId"
,
"name":
"type": "text"
,
"geo":
"type": "point"
,
"descriptives": ,
"dates":
,
"id": 1,
"events": null,
"name": "Madison Square Garden",
"geo": [
40.7505,
73.9934
]
搜索 Madison Square Garden 作为位置名称以了解 JSON 结构。 您可以在对象设置中设置描述性字段
【讨论】：
我如何获得描述性值？ 以及相关的对象值？以上是关于如何从对象的外键中获取对象的值？的主要内容，如果未能解决你的问题，请参考以下文章