Making query string parameters to change specific data field for RESTful APIs

Question

I am new to RESTful APIs and I've successfully implemented the GET and DELETE methods for my API (GET localhost:4000/api, DELETE localhost:4000/api on Postman works fine).

What I want to implement now is to specify the order in which to sort each specific field where 1 is ascending and -1 is descending. For example,

If I do localhost:4000/api/users?sort = { fieldName : 1 }

This will return a list of users sorted by 'fieldName'.

I tried to do

router.get('/', function(req, res) {
  var sort = req.query.sort;

  user
   .find({})
   .sort({"name": sort}) 
   .exec(function(err, users) {
      if(err){
          res.status(404).send({
              message: err,
              data: []
          });
      } else {
          res.status(200).send({
              message: 'OK',
              data: users
          });
      }
  });
});

But since the "name" part is hard-coded, it only works for names. I want to let the user specify the field name and sort the list based on it.

What do I have to add?

EDIT: This is how my data looks like

{
    "message": "OK",
    "data": [
        {
            "_id": "59faba588f3f6211ac7db43c",
            "name": "Kim2",
            "email": "[email protected]",
            "__v": 0,
            "dateCreated": "2017-11-02T06:25:28.225Z",
            "pendingTasks": []
        },
        {
            "_id": "59facf56e8c5663343d4b644",
            "name": "Minnie Payne",
            "email": "[email protected]",
            "__v": 0,
            "dateCreated": "2017-11-02T07:55:02.552Z",
            "pendingTasks": []
        },
        {
            "_id": "59fb699c3c00c60990fa6edb",
            "name": "jerry watson",
            "email": "[email protected]",
            "__v": 0,
            "dateCreated": "2017-11-02T18:53:16.637Z",
            "pendingTasks": []
        }, ...

EDIT2

  user
   .find({})
   .sort('name') 
   .exec(function(err, users) {
      if(err){
          res.status(404).send({
              message: err,
              data: []
          });
      } else {
          res.status(200).send({
              message: 'OK sorted',
              data: users
          });
      }
  });

req.query items all all "strings". If you want an object from JSON as parameter values, then use JSON.parse. i.e .sort({ name: JSON.parse(req.query.sort) }) where req.query.sort is the "string" '{ "fieldName": 1 }'. Noting that JSON expects quoted "keys". — Neil Lunn
– Neil Lunn, Commented Nov 3, 2017 at 2:48
Sorry, could you actually elaborate your solution in the answer? I think I get the idea, but I really don't get how to do this in the code. — Dawn17
– Dawn17, Commented Nov 4, 2017 at 2:52

radar155 · Accepted Answer · 2017-11-04 15:42:28Z

1

What you want to do is to name an object property by a string. To do it you can do something like:

var string = 'name'
var obj = {}
obj[string] = 'val'
console.log(obj) // {name: 'val'}

So, in your example:

router.get('/', function(req, res) {
  var sort = req.query.sort;
  var name = req.query.name;
  var obj = {}
  obj[name] = sort

  user
   .find({})
   .sort(obj) 
   .exec(function(err, users) {
      if(err){
          res.status(404).send({
              message: err,
              data: []
          });
      } else {
          res.status(200).send({
              message: 'OK',
              data: users
          });
      }
  });
});

EDIT: solution with localhost:4000/api/users?sort={fieldName: 1}

router.get('/', function(req, res) {
  let obj = JSON.parse(req.query.sort)

  user
   .find({})
   .sort(obj) 
   .exec(function(err, users) {
      if(err){
          res.status(404).send({
              message: err,
              data: []
          });
      } else {
          res.status(200).send({
              message: 'OK',
              data: users
          });
      }
  });
});

edited Nov 4, 2017 at 15:42

answered Nov 3, 2017 at 2:26

radar155

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10 Comments

Dawn17 Over a year ago

But isn't this pretty much hard coding the field 'name' ? I want to specify the field name on the URL directly. e.g. localhost:4000/api/users?sort={fieldName: 1} where fieldName can be any existing field like 'name', 'id', 'date', etc.

radar155 Over a year ago

it's exactly what the code does! look at line 3. The name variable is taken from query string

Dawn17 Over a year ago

Thanks! I just tried but it seems like it's not sorting. What I actually wanted was sorting based on whether the value for the sort query is -1 or 1 (1- ascending; -1 - descending). So that localhost:3000/api/users?sort={"name": 1} this would sort the names in ascending order.

radar155 Over a year ago

if you want to pass directly {"name":1} in the query string, you need to parse string. So obj = JSON.parse(req.query.fieldname)

radar155 Over a year ago

no. i proposed you two solution. the first one (in my answer, where a edited your code) you can use your api in this way: localhost:3000/api/users?name=yourkey&sort=1. Then, my 2nd comment i proposed an alternative solution based on your querystring format (you want to send to server localhost:3000/api/user?sort={yourkey: 1}. In this scenario, you should JSON.parse(req.query.sort). This will create an object that you can pass to your sort function. Both the solution are not hardcoded and take the key name you want order to from query string.

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