Can't return my result in async method

Question

In an MVVM pattern I'm trying to make an async method that fetches a json string, and returns the result as a List<Cabinet> so that I can use this list later.

I have json that looks like this, it represents a list of cabinet object:

{"cabinets":[{"id":"1","longitudeGPS":"2,2891506","latitudeGPS":"48,8618687","cp":"75016","ville":"Paris","rue":"1 Avenue Gustave V de Su\u00e8de"},{"id":"2","longitudeGPS":"3,0566481","latitudeGPS":"50,6302592","cp":"59800","ville":"Lille","rue":"127 Rue Solf\u00e9rino"},{"id":"3","longitudeGPS":"3,8749271","latitudeGPS":"43,6110374","cp":"34000","ville":"Montpellier","rue":"17 Rue Foch"},{"id":"4","longitudeGPS":"-1,6736931","latitudeGPS":"48,1181043","cp":"35700","ville":"Rennes","rue":"127 23 Rue de Vincennes"},{"id":"5","longitudeGPS":"0,0991065","latitudeGPS":"49,4931952","cp":"76600","ville":"Le Havre","rue":"32 Avenue Foch"},{"id":"6","longitudeGPS":"4,8353320","latitudeGPS":"45,7639021","cp":"69002","ville":"Lyon","rue":"27 Rue Henri Germain"}]}

I've created the classes according to json2csharp generator:

public class Cabinet
{
    public string id { get; set; }
    public string longitudeGPS { get; set; }
    public string latitudeGPS { get; set; }
    public string cp { get; set; }
    public string ville { get; set; }
    public string rue { get; set; }
}

public class CabinetList
{
    public List<Cabinet> cabinets { get; set; }
}

Here I have an HttpClient that fetches the json from the website and stores it in a listCabinet variable.

public string adresseCabinets = "http://ppe3JoJuAd/gsbAppliFraisV2/webservices/w_cabinet.php";
public static string userId;

CabinetsList listeCabinets = new CabinetsList();
public async Task<List<CabinetsList>>loadCabinets()
{
    HttpClient clientCabinets = new HttpClient();
    var response = await clientCabinets.GetAsync(adresseCabinets);
    var json = response.Content.ReadAsStringAsync().Result;
    listeCabinets = JsonConvert.DeserializeObject<CabinetsList>(json);
}

When I want to return the listeCabinets variable I have the following error: cannot implicitly convert type cabinetList to System.Collection.Generic.List CabinetList

How can I solve this?

You aren't returning anything, you should show that code. You also use .Result which is bad practice, use await instead like before. — TheLethalCoder
– TheLethalCoder, Commented May 8, 2017 at 12:21
listeCabinets is of type CabinetList, and your return value should be of type List<CabinetsList>. You'll need to convert CabinetsList to List<Cabinet>. — Stephen Cleary
– Stephen Cleary, Commented May 8, 2017 at 12:22
May be you need to declare method as public async Task<CabinetsList> loadCabinets() — Sarvesh Mishra
– Sarvesh Mishra, Commented May 8, 2017 at 12:25

Patrick Hofman · Accepted Answer · 2017-05-08 12:23:09Z

2

The return type of your method is List<CabinetsList>, while the output of DeserializeObject<CabinetsList> is a CabinetsList. You should deserialize the JSON as the type you want to return:

return JsonConvert.DeserializeObject<List<CabinetsList>>(json);

Or create a new list to add the one and only cabinet to if the JSON contains just one:

return new List<CabinetsList> { JsonConvert.DeserializeObject<CabinetsList>(json) };

Side note: and of course await the result:

var json = await response.Content.ReadAsStringAsync();

edited May 8, 2017 at 12:23

answered May 8, 2017 at 12:21

Patrick Hofman

158k23 gold badges270 silver badges343 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

TheLethalCoder Over a year ago

Whilst this is most likely correct, I believe it would be worth noting that the OP uses .Result on the ReadAsStringAsync method when they should be using await.

Patrick Hofman Over a year ago

Does he really do that? Edited @TheLethalCoder

En_Tech_Siast Over a year ago

Thank you, I'll try and let you know. Sorry if there is any mistakes in the code I'm still learning how to use asynchronous coding.

Collectives™ on Stack Overflow

Can't return my result in async method

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related