Adding pagination cursor and additional features to endpoint result

Question

Strongloop api has been great to work with right out of the box. However I am currently trying to make some customizations. I am trying to add to the category model a remote method that returns along with the endpoint data the following: perPage, total, paging(shown below in more details). For paging the before and after are parameters based on gameId. limit will default to 5 if value is null or greater than 5. What would be the best way to append to result the previously mentioned?

For example, http://localhost:3000/api/Categories/1004/games/mature?before=1000053 will return all gameId less than 1000053 and before all gameIds greater than 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);
        });
    });

Endpoint results for /Categories/1004/games/mature

{
      “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
      }
  }

notbrain · Accepted Answer

To add results to the response, first change the type of response that the Category.mature remote method returns to an object:

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()
  }
});

Then just add the values you want to the new games object, using your existing gamesArr as the value for data, and the values passed in for the limit, before, and after values into the response object as the 2nd argument to the success callback:

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
  }
})

As I mentioned about the multiple Games.find() calls that were overcomplicating the code, you also shouldn't plunk down 3 or 4 copies of that object either. You can wrap the construction of the object in logic, then have a single callback() call to simplify the remote method's I/O management and write less code. Reducing to a single Games.find() call will make sending this result easier.

Also keep an eye out for curly apostrophe characters and tabs vs space indentation (pick one and stick with it, don't mix), it's much easier to help out when your code is constructed and organized with care.

Adding pagination cursor and additional features to endpoint result

Answers (2)

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