How to convert key value pair to a custom object list

Question

I have a keyValupair of Hotel details:

//This is where the data comes from : -

JavaScriptSerializer json_serializer = new JavaScriptSerializer();
dynamic hotels1 = (dynamic)json_serializer.DeserializeObject(jso);
var keyValuePairs = hotels1["hotels"];

var hotelList = keyValuePairs["hotels"];   // hotelList[0]  ={'key'='Code' ;value='123'} 
                                           //{'key'='Name' 
                                           // ;value='Sheraton'}

how do I convert this to a list of Hotel

List<Hotel> hotaals = new List<Hotel>();

where Hotel is

public class Hotel {
    public int code { get; set; }
    public string name { get; set; }
}

I use a for loop to map fields, but my great boss says it's inefficient and I have to use Linq.

The loop I use

foreach (dynamic h in hotelList) {

   oneHotel = new Hotel();
   oneHotel.code = h["code"];
   oneHotel.name = h["name"];
   myHotels.Add(oneHotel);
}

Do you mean you have a `Dictionary` you need to convert to a `List`, where the memebers of the class don't match the KeyValuePair(s) of your Dictionary? About the loop being inefficient (...). — Jimi, Oct 08 '19 at 21:42
Is a loop inefficient for the executing performance or speed of programming? If your "great boss" thinks smaller code means faster executing, he could be wrong. (https://stackoverflow.com/questions/1044236/nested-foreach-vs-lambda-linq-query-performancelinq-to-objects) — GvS, Oct 08 '19 at 21:43
Please include an actual definition for `hotelList`. Pseudo-code and undefined code samples can make it hard to provide a detailed answer. — Rufus L, Oct 08 '19 at 21:55
If you're already using a for loop, why not post the code? It would make the question very clear. — John Wu, Oct 08 '19 at 22:04
A little off topic but I utilize Json.NET library to interact with JSON from my javascript front end calls. It makes converting JSON into .NET objects a breeze. https://www.newtonsoft.com/json — nulltron, Oct 08 '19 at 22:56

nulltron · Answer 1 · 2019-10-08T22:04:15.010

So first you get your initial data:

var hotelList = keyValuePairs["hotels"];

Then use linq to create your new list:

var hotelObjects = hotelList.Select(hotel => new Hotel { code = hotel.key, name = hotel.name});

Now to be clear what linq is doing under the hood is an iterative loop through the objects (just like foreach) and creates a new Hotel object for each item in the hotelList and returns them as an IQueryable<Hotel>. Just apply .ToArray() or .ToList() if you don't want an IQueryable<>

Now from what it sounds like your initial List of hotel details isn't structured so you might have to modify my supplied linq query above to suit the structure of the list.

You may need something closer to this:

// Gives IQueryable<Hotel> as result
var hotelObjects = hotelList.Select(hotel => new Hotel{code = hotel["key"], name = hotel["name"]});

// Gives Array<Hotel> as result
var hotelObjects = hotelList.Select(hotel => new Hotel{code = hotel["key"], name = hotel["name"]}).ToArray();

// Gives List<Hotel> as result
var hotelObjects = hotelList.Select(hotel => new Hotel{code = hotel["key"], name = hotel["name"]}).ToList();

score 1 · Answer 2 · answered Oct 08 '19 at 21:58

Well the brute force way would be to just project the dictionary to objects by hard-coding the properties:

List<Hotel> hotaals = hotelList.Select(kvp => new Hotel {
                                    code = kvp['Code'],
                                    name = kvp["Name"]
                                    })
                               .ToList();

I would also challenge what your "great boss" means by inefficient".

How to convert key value pair to a custom object list

2 Answers2