Btukfyl

I'm trying to parse some Json in Xamarin.Forms

I'm pretty new to Xamarin, though not to .net

Here's my simple dimple code

        var htc = new HttpClient();

        var rsp = await htc.GetStringAsync("myurl.com");

        JArray lists = JArray.Parse(rsp);

        var c = lists.Count();

        var l = lists.ToList();

        var w=lists.Where(x => true);

Even though c returns the correct count of items in the list, l & w are both null

How come? and how do I fix it?

Thanks!

PS. What I'm really trying to do is bind a ListView to a JArray, but it seems impossible directly,(Text={Binding MyPropertyName} crashes the app). so I'm trying to run a Select on the JArray to convert to a KeyValuePair. If you have any ideas to bind directly, that would be best!

UPDATE

The issue seems even odder

I tried this

 var kvlist = new List<KeyValuePair<string, string>>();



        foreach (JObject ll in lists)

        {

            kvlist.Add(new KeyValuePair<string, string>(ll["Name"].ToString(), ll["Name"].ToString()));

        }

Here at least the iteration works nicely, but the kvlist is null the entire time. Trying to evaluate the kvlist variable, I get:

Unable to cast object of type 'System.RuntimeType' to type
'Mono.Debugger.Soft.TypeMirror'.

What can the matter be?

Thanks again!

You should not directly call .ToList on object type of JArray rather you should Select List of type you need. For ex.

var l = lists.Select(c => new MyList

{

    Item1 = c.Value<int>("ItemName1"),

    Item2 = c.Value<string>("ItemName2")

}).ToList(); //Replce MyList with your class name 

On the second case where w is null, after getting list l you need to specify attribute, based of what you are using where clause. For ex.

var w=l.Where(x =>x.isAdmin==true); //l is list you selected above

Hope it help you.

Solution:

You can use code below to convert a JArray to a list<T>:

List<T> t =lists.ToObject<List<T>>();

Refer: https://www.newtonsoft.com/json/help/html/ToObjectType.htm

You could also use JsonConvert.DeserializeObject to convert it directly into the desired type. You have to define a jsonModel class with the same structure of your json fisrtly.

List<jsonModel> modelList = JsonConvert.DeserializeObject<List<jsonModel>>(jsonStr);

Refer :https://www.newtonsoft.com/json/help/html/SerializingCollections.htm

The documentation seems to indicate that JArray has properties for .Count, but no overload method because it does not implement IEnumerable, however as alluded to in the comments, it does implement the JToken type (which JArray is a collection of) and implements IEnumerable.
See the following documentation for JToken: https://www.newtonsoft.com/json/help/html/T_Newtonsoft_Json_Linq_JToken.htm
and JArray respectively:
https://www.newtonsoft.com/json/help/html/T_Newtonsoft_Json_Linq_JArray.htm

The preferred mechanism is to create a strong type and then run .ToObject();
You can access JArray.ChildrenTokens which may help