将分页光标和附加功能添加到端点结果

Question

Strongloop api 开箱即用，非常棒。但是，我目前正在尝试进行一些自定义。我正在尝试向category 模型添加一个远程方法，该方法与端点数据一起返回以下内容：perPage、total、paging（详细信息如下所示）。对于paging，before 和after 是基于gameId 的参数。如果值为null 或大于5，limit 将默认为5。附加到前面提到的结果的最佳方法是什么？

例如，http://localhost:3000/api/Categories/1004/games/mature?before=1000053 将返回所有小于1000053 的gameId 和所有before 大于1000053 的gameIds。

common/models/category.js

  Category.findById(id, {}, function(err, category){
        if (err) return callback(err);
        //set limit
        if (limit && limit > 5){
          limit = 5;
        }else if(limit === undefined){
          limit = 5;
        }
        //set after cursor
        Games.find({
            "where": {
                categoryId: id,
                mature: true,
                gameId: {gt: after}
            },
            "limit": limit
        }, function(err, gameArr) {
            if (err) return callback(err);
            callback(null, gameArr);
        });
    });

/Categories/1004/games/mature 的端点结果

{
      “perPage”: 5, //value from limit
      “total”: 5, //total of return items from array
      "data": [
         ... Endpoint data is here
      ],
      "paging": {
        "cursors": {
          "after": 1000057, //last item in array
          "before": 1000053 //first item in array
        },
        "previous": "http://localhost:3000/api/Categories/1004/games/mature?before=1000053" //url for previous
        "next": "http://localhost:3000/api/Categories/1004/games/mature?after=1000057" //url for after
      }
  }

Answer 1

要将结果添加到响应中，首先更改 Category.mature 远程方法返回给对象的响应类型：

Category.remoteMethod('mature', {
  accepts: [
    {arg: 'id', type: 'number', required: true},
    {arg: 'limit',type: 'number',required: false},
    {arg: 'after',type: 'number',required: false},
    {arg: 'before',type: 'number',required: false}   
  ],
  // mixing ':id' into the rest url allows $owner to be determined and used for access control
  http: {
    path: '/:id/games/mature',
    verb: 'get'
  },
  returns: {
    arg: 'games',
    type: 'object' // will be whatever you pass back as 2nd arg to callback()
  }
});

然后只需将您想要的值添加到新的游戏对象中，使用您现有的 gamesArr 作为 data 的值，并将为限制、之前和之后传入的值作为第二个参数传入响应对象到成功回调：

callback(null, {
  "perPage": limit,
  "total": gameArray.length,
  "data": gameArray,
  "paging": {
    "cursors": {
      "after": gameArray[gameArray.length-1].game_id, // last game_id in result
      "before": gameArray[0].game_id // first game_id in result
    },
    "previous": "http://localhost:3000/api/Categories/1004/games/mature?before=" + gameArray[0].game_id,
    "next": "http://localhost:3000/api/Categories/1004/games/mature?after=" + gameArray[gameArray.length-1].game_id
  }
})

正如我提到的使代码过于复杂的多个 Games.find() 调用，您也不应该删除该对象的 3 或 4 个副本。您可以将对象的构造封装在逻辑中，然后调用一个 callback() 来简化远程方法的 I/O 管理并减少代码编写。减少到单个 Games.find() 调用将更容易发送此结果。

还要注意花撇号字符和制表符与空格缩进（选择一个并坚持使用，不要混用），当您的代码构建和组织得当时，它会更容易提供帮助。

Answer 2

这里的问题是您使用 Category 模型作为入口点，而您似乎应该使用 Game 模型的内置查询方法以及过滤器、限制和偏移量，句号。这将允许您在不需要添加所有这些复杂性来支持您的之前/之后概念的情况下进行分页。这是不必要的。 如果你的关系设置正确，你只需要对游戏进行分页就是一个游戏模型查询！

例如，您似乎需要一个在特定类别中成熟的游戏的分页列表，对吗？要获得符合这些条件的 5 场比赛的结果，您需要发送一个 json REST API 调用，如下所示：

http://0.0.0.0:3000/api/Games?filter=%7B%20%22where%22%3A%20%7B%22mature%22%3Atrue%2C%20%22categoryId%22%3A%201004%7D%2C%20%22offset%22%3A%200%2C%20%22limit%22%3A%205%20%7D

这很难阅读，因为它是编码的，但底层过滤器是这样构造的：

{ "where": {"mature":true, "categoryId": 1004}, "offset": 0, "limit": 5 }

这将返回以下数据集，即前 5 款属于 1004 categoryId 且同样成熟的游戏：

[
  {
    "mature": true,
    "gameName": "CODBlacOps3",
    "categoryId": 1004,
    "gameId": 1000053,
    "description": "Published by Activision",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Evolve",
    "categoryId": 1004,
    "gameId": 1000054,
    "description": "Published by Turtle Rock Studios",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Battlefield4",
    "categoryId": 1004,
    "gameId": 1000055,
    "description": "Published by EA Digital Illusions",
    "publishedDate": "2013-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Rainbow6",
    "categoryId": 1004,
    "gameId": 1000056,
    "description": "Published by EUbisoft",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Destiny",
    "categoryId": 1004,
    "gameId": 1000057,
    "description": "Published by Bungie",
    "publishedDate": "2014-01-01T00:00:00.000Z"
  }
]

要获得 5 个游戏的下一页，我们只需将偏移量更改为 5，这会告诉数据库跳过前 5 个，因为我们现在在第 2 页：

{ "where": {"mature":true, "categoryId": 1004}, "offset": 5, "limit": 5 }

这将返回以下结果：

[
  {
    "mature": true,
    "gameName": "Wolfenstein",
    "categoryId": 1004,
    "gameId": 1000058,
    "description": "Published by Bethesda",
    "publishedDate": "2014-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "StarWarsBattleFront",
    "categoryId": 1004,
    "gameId": 1000059,
    "description": "Published by EA DICE",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Test1",
    "categoryId": 1004,
    "gameId": 1000060,
    "description": "Published by Test1",
    "publishedDate": "2015-12-19T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Test2",
    "categoryId": 1004,
    "gameId": 1000061,
    "description": "Published by Test2",
    "publishedDate": "2015-12-19T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Test3",
    "categoryId": 1004,
    "gameId": 1000062,
    "description": "Published by Test3",
    "publishedDate": "2015-12-19T00:00:00.000Z"
  }
]

默认情况下，游戏按照其 game_id 的顺序排列。无需自定义远程方法和嵌套的 find()！

如果您想按字母顺序排列列表，还可以添加order 过滤器，并将其设置为"order": "gameName ASC"：

{ "where": {"mature":true, "categoryId": 1004}, "offset": 0, "limit": 5, "order": "gameName ASC" }

这将返回一个新的（第 1 页，因为我将偏移量设置回 0）游戏数组，按字母顺序按 gameName 排序：

[
  {
    "mature": true,
    "gameName": "Battlefield4",
    "categoryId": 1004,
    "gameId": 1000055,
    "description": "Published by EA Digital Illusions",
    "publishedDate": "2013-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "CODBlacOps3",
    "categoryId": 1004,
    "gameId": 1000053,
    "description": "Published by Activision",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Destiny",
    "categoryId": 1004,
    "gameId": 1000057,
    "description": "Published by Bungie",
    "publishedDate": "2014-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Evolve",
    "categoryId": 1004,
    "gameId": 1000054,
    "description": "Published by Turtle Rock Studios",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  },
  {
    "mature": true,
    "gameName": "Rainbow6",
    "categoryId": 1004,
    "gameId": 1000056,
    "description": "Published by EUbisoft",
    "publishedDate": "2015-01-01T00:00:00.000Z"
  }
]

我之所以能够如此迅速地得到这个结果，是因为使用了 API Explorer。我分叉了您的项目，更改了数据库连接值以匹配我的本地服务器，启动它，然后转到 http://0.0.0.0/explorer/#!/Games/Games_find，然后在 Games 模型上使用不同的 filter 值：