向端点结果添加分页游标和其他功能

Question

Strongloop api 非常适合开箱即用。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 returns 以及以下端点数据：perPage、total、paging（显示下面详细介绍）。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 return 所有 gameId 小于 1000053 和 before 所有 gameIds 大于 1000053.

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

这里的问题是您使用类别模型作为入口点，而您似乎应该使用带有过滤器、限制和偏移量的游戏模型的内置查询方法，句号。这将使您无需添加所有这些复杂性即可进行分页以支持您的 before/after 概念。这是不必要的。 如果你的关系设置正确，你只需要在游戏上分页就是一个游戏模型查询！

例如，您似乎需要一个特定类别中成熟游戏的分页列表，对吗？要获得符合这些条件的 5 场比赛的结果，您可以像这样发送 json REST API 调用：

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return以下数据集，这是1004 categoryId 中的前 5 个游戏：

[
  {
    "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"
  }
]

要获取 5 场比赛的下一页，我们只需将偏移量更改为 5，这会告诉数据库跳过前 5 场，因为我们现在是第 2 场页数：

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

这 return 结果如下：

[
  {
    "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 game_id 的顺序排列。无需自定义远程方法和嵌套查找 ()！

如果您想按字母顺序排列列表，您还可以添加 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 return 一个新的（第 1 页，因为我将偏移量设置回 0）游戏数组，按 gameName:

的字母顺序排列

[
  {
    "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"
  }
]

我能够如此快速地得到这个结果的方法是使用 API Explorer。我分叉了你的项目，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 然后在游戏模型上玩不同的 filter 值：

Answer 2

要将结果添加到响应中，首先将 Category.mature 远程方法 returns 的响应类型更改为对象：

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游戏对象，使用您现有的 gameArr 作为 data 的值，并将限制、之前和之后的值传递到响应对象中作为成功回调的第二个参数：

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() 调用一样，您也不应该复制该对象的 3 或 4 个副本。您可以在逻辑中包装对象的构造，然后调用单个 callback() 来简化远程方法的 I/O 管理并编写更少的代码。减少到单个 Games.find() 调用将使发送此结果更容易。

还要注意卷曲撇号字符和制表符与 space 缩进（选择一个并坚持使用，不要混用），在构建和组织代码时更容易提供帮助小心。

向端点结果添加分页游标和其他功能

Adding pagination cursor and additional features to endpoint result

node.js

loopbackjs

strongloop