I am trying to get some currency values from an api. it's returning the data in the following format:
{"PKR_PKR":{"val":1}}
I want to show this value in textbox but there's an error
"Object reference not set to an instance of object".
I've tried the following code:
try
{
string endPoint = #"http:urlhere";
string ResultJson = "";
using (WebClient wc = new WebClient())
{
ResultJson = wc.DownloadString(endPoint);
}
JsonData values = JsonConvert.DeserializeObject<JsonData>(ResultJson);
txtBalanceRate.Text = values.CurrencyValue.ToString();
}
catch (Exception ex) { }
Class code:
class JsonData
{
public object CurrencyValue { get; set; }
}
**
UPDATE
**
Note: I can not update PKR_PKR Class becuase every time the name of variable is different for different currencies i.e. it can be USD_PKR , EUR_PKR etc
How can I resolve this?
FOLLOWING IS THE UPDATED CODE:
try
{
string endPoint = #"http://free.currencyconverterapi.com/api/v5/convert?q="+ddlCurrency.SelectedValue.ToString()+"_PKR&compact=y";
string ResultJson = "";
using (WebClient wc = new WebClient())
{
ResultJson = wc.DownloadString(endPoint);
}
RootObject rootObject = JsonConvert.DeserializeObject<RootObject>(ResultJson);
txtBalanceRate.Text = rootObject.PKR_PKR.val.ToString();
}
catch (Exception ex)
{
}
public class PKRPKR
{
public int val { get; set; }
}
public class RootObject
{
public PKRPKR PKR_PKR { get; set; }
}
If you are going to have dynamic object then you should try this out
dynamic data = Newtonsoft.Json.JsonConvert.DeserializeObject(json);
Type typeOfDynamic = data.GetType();
if( typeOfDynamic.GetProperties().Where(p => p.Name.Equals("PKR_PKR")).Any())
{
console.WriteLine(data.PKR_PKR.val);
}
else if( typeOfDynamic.GetProperties().Where(p => p.Name.Equals("USD_PKR")).Any())
{
console.WriteLine(data.USD_PKR.val);
}
else if( typeOfDynamic.GetProperties().Where(p => p.Name.Equals("EUR_PKR")).Any())
{
console.WriteLine(data.EUR_PKR.val);
}
above way is not tried and tested but you can have try like this as you json is dynamic.
Above way is checking property exist or not and get val from dynamci object
Your class structure is incorrect can you please try below class structure
public class PKRPKR
{
public int val { get; set; }
}
public class RootObject
{
public PKRPKR PKR_PKR { get; set; }
}
RootObject rootObject = JsonConvert.DeserializeObject<RootObject>(json);
Console.WriteLine(rootObject.PKR_PKR.val);
Mostly if you see above class structure , you josn each node is represent as class, but I dont go in much detail as Visual studio can do it for me.
When comes to json to object conversion ,I make use of utility provided by Visual studio. which does conversion of json string to proper class structure. here is image of it
Read how to do it full here :
Visual Studio Generate Class From JSON or XML
If you dont have visual studio with this feature you can use this online utility : json2csharp
Note: I can not update PKR_PKR Class becuase evert time the name of
variable is different for different currencies i.e. it can be USD_PKR
, EUR_PKR etc How can I resolve this?
SOLUTION
if json string {"PKR_PKR":{"val":1}} is fixed in your case, you can use following solution for any currency name you got.
static void Main(string[] args)
{
string json1 = "{ \"PKR_PKR\":{ \"val\":1}}";
string json2 = "{ \"USD_PKR\":{ \"val\":2}}";
string json3 = "{ \"EUR_PKR\":{ \"val\":3}}";
JToken token1 = (JToken)JsonConvert.DeserializeObject(json1);
Console.WriteLine(token1.First().First()["val"]);
JToken token2 = (JToken)JsonConvert.DeserializeObject(json2);
Console.WriteLine(token2.First().First()["val"]);
JToken token3 = (JToken)JsonConvert.DeserializeObject(json3);
Console.WriteLine(token3.First().First()["val"]);
Console.ReadLine();
}
I think your receiving object should contain a dictionary, not a single string:
Check this
Or you have to improve your object structure implementing a root item which contains a PKR_PKR sub object
Is there a way to make a function return the type of object I pass in? I would like to call the one method below to return the type I pass in. Is that possible? Should I even be trying to do this? Is there a better way...short of having two different methods?
Currently, I tried the first two calls and I get back (with the first call) what looks like a dictionary with a system.object[] in the value part of the dictionary. Screen shot below might show it better than my explanation. I ask this as I might have more types that I need to deserialize and don't want to have a different method for each.
var firstTry = this.Deserialize(path, typeof(ObservableCollection<ListItemPair>();
var secondTry = this.Deserialize(path, typeof(ListItemPair));
var thirdTry = this.Deserialize(path, typeof(SomeOtherObject));
public static object Deserialize(string jsonFile, object type)
{
var myObject = new object();
try
{
using (StreamReader r = new StreamReader(jsonFile))
{
var serializer = new JavaScriptSerializer();
string json = r.ReadToEnd();
myObject = serializer.Deserialize<object>(json);
}
}
catch (Exception ex)
{
}
return myObject ;
}
public class ListItemPair
{
public string Name
{
get;
set;
}
public object Value
{
get;
set;
}
}
object created:
Yes, you can create a generic method. Your Deserialize() method would look something like this:
public static T Deserialize<T>(string jsonFile)
{
T myObject = default(T);
try
{
using (var r = new StreamReader(jsonFile))
{
var serializer = new JavaScriptSerializer();
string json = r.ReadToEnd();
myObject = serializer.Deserialize<T>(json);
}
}
catch (Exception ex)
{
}
return myObject;
}
In this example T is a type parameter. When invoking this method, you can pass the type like this:
var firstTry = Deserialize<ObservableCollection<ListItemPair>>(path);
var secondTry = Deserialize<ListItemPair>(path);
var thirdTry = Deserialize<SomeOtherObject>(path);
One side note: I wouldn't recommend silently swallowing an exception. In this case, it is expected that the deserialization can fail. Therefore, I would change it to a TryDeserialize() method:
public static bool TryDeserialize<T>(string jsonFile, out T myObject)
{
try
{
using (var r = new StreamReader(jsonFile))
{
var serializer = new JavaScriptSerializer();
string json = r.ReadToEnd();
myObject = serializer.Deserialize<T>(json);
}
}
catch (Exception ex)
{
myObject = default(T);
return false;
}
return true;
}
problably I'm not experienced enought and my question is kind of dumb:
For learning purposes I'm trying to connect to a REST-Service, which delivers JSON-Data.
From what I've learned, the purpose of JSON is to deliver the same data to any possible client without having a State of itself.
My code is looking like this:
public static void DoSomething()
{
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("SomeUrl"));
// Add an Accept header for JSON format.
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
// List data response.
HttpResponseMessage response = client.GetAsync("").Result;
if (response.IsSuccessStatusCode)
{
Task<Stream> readTask = response.Content.ReadAsStreamAsync();
readTask.ContinueWith(task =>
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(RootObject));
using (Stream result = task.Result)
{
result.Position = 0;
RootObject obj = (RootObject)ser.ReadObject(result);
}
});
}
else
{
Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
}
}
public class Sum
{
public int id { get; set; }
public string name { get; set; }
public int profileIconId { get; set; }
public int summonerLevel { get; set; }
public long revisionDate { get; set; }
}
public class RootObject
{
public Sum khalgor { get; set; }
}
But here's my Problem: I've created this classes "Sum" and "RootObject" by using the Website http://json2csharp.com/, the JSON-String is looking like this:
{"khalgor":{"id":23801741,"name":"Khalgor","profileIconId":7,"summonerLevel":30,"revisionDate":1396876104000}}
The Problem: The Name "Khalgor" seems to be used as a Root-Object, but it's a Name. So if I'd like to user for another Name, I'd have to user another RootObject.
It does not make that much sense to create such a Structure, so my question: What's the best practice here? Do I map this RootObject/Property to another object manually? Do I use some Reflection to dynamically create an Property or rename it?
As usual, thanks a lot for all Responses
Matthias
Edit:
I tinkered arround a bit and that's my first idea of a solution:
public static class LOLObjectFactory
{
public static ILOLObject Create(string jsonString)
{
JavaScriptSerializer jss = new JavaScriptSerializer();
Dictionary<String, object> entry = (jss.Deserialize<dynamic>(jsonString) as Dictionary<string, object>).First().Value as Dictionary<String, object>;
Type selectedType = null;
List<string> fieldNames = entry.Select(f => f.Key).OrderBy(f => f).ToList();
Type[] types = typeof(ILOLObject).Assembly.GetTypes();
foreach(var type in types)
{
List<string> typeProperties = type.GetProperties().Select(f => f.Name).OrderBy(f => f).ToList();
if (fieldNames.SequenceEqual(typeProperties) && typeof(ILOLObject).IsAssignableFrom(type))
{
selectedType = type;
break;
}
}
ILOLObject result = System.Activator.CreateInstance(selectedType) as ILOLObject;
foreach(var prop in result.GetType().GetProperties())
{
prop.SetValue(result, entry.First(f => f.Key == prop.Name).Value);
}
return result;
}
}
So all the objects I have have the ILOLObject implemented. I'm sure it's not working for everything, but I guess that would be a good approach?
Edit2: Just by looking at it I see I'll have a lot of work to do, but I think the idea behind it is quite clear.
I think your best bet for json "fragments" is to deserialize into a dynamic object:
dynamic stuff = JsonConvert.DeserializeObject(inputData);
Then you can deserialize parts that make sense into proper .NET objects.
SomeObject o = JsonConvert.DeserializeObject<SomeObject>(stuff["someProperty"].ToString());
If you want to ignore the root altogether (e.g. it changes its name everytime) use Json.NET to parse it into an object and ignore the topmost element. Example:
JObject obj = JObject.Parse(json);
if (obj != null)
{
var root = obj.First;
if (root != null)
{
var sumJson = root.First;
if (sumJson != null)
{
var sum = sumJson.ToObject<Sum>();
}
}
}
I have the following class:
public class TestQuestionHeader
{
public int Id { get; set; }
public int QId { get; set; }
}
and JSON methods:
public static string ToJSONString(this object obj)
{
using (var stream = new MemoryStream())
{
var ser = new DataContractJsonSerializer(obj.GetType());
ser.WriteObject(stream, obj);
return Encoding.UTF8.GetString(stream.ToArray());
}
}
public static T FromJSONString<T>(this string obj)
{
using (var stream = new MemoryStream(Encoding.UTF8.GetBytes(obj)))
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
T ret = (T)ser.ReadObject(stream);
return ret;
}
}
I am using these as follows:
IList<TestQuestionHeaders> testQuestionHeaders = xxx;
string test.Questions = JSON.ToJSONString(testQuestionHeaders);
var a = JSON.FromJSONString<TestQuestionHeader>(test.Questions);
Can someone help me to explain why the variable a contains TestQuestionHeader
instead of IList<TestQuestionHeader>
Your FromJSONString method returns an instance of type T. Your call in your example passes TestQuestionHeader as T. You just need to supply the correct type for T.
You'll need to change that line to:
var a = JSON.FromJSONString<List<TestQuestionHeader>>(test.Questions);
That's because your passing TestQuestionHeader as generic type parameter. Try following:
IList<TestQuestionHeader> a = JSON.FromJSONString<List<TestQuestionHeader>>(test.Questions);
Use JSON.NET, the best JSON library for .NET.
See: http://james.newtonking.com/json/help/index.html
Trying to convert a JSON string into an object in C#. Using a really simple test case:
JavaScriptSerializer json_serializer = new JavaScriptSerializer();
object routes_list = json_serializer.DeserializeObject("{ \"test\":\"some data\" }");
The problem is that routes_list never gets set; it's an undefined object. Any ideas?
Or, you can use the Newtownsoft.Json library as follows:
using Newtonsoft.Json;
...
var result = JsonConvert.DeserializeObject<T>(json);
Where T is your object type that matches your JSON string.
It looks like you're trying to deserialize to a raw object. You could create a Class that represents the object that you're converting to. This would be most useful in cases where you're dealing with larger objects or JSON Strings.
For instance:
class Test {
String test;
String getTest() { return test; }
void setTest(String test) { this.test = test; }
}
Then your deserialization code would be:
JavaScriptSerializer json_serializer = new JavaScriptSerializer();
Test routes_list =
(Test)json_serializer.DeserializeObject("{ \"test\":\"some data\" }");
More information can be found in this tutorial:
http://www.codeproject.com/Tips/79435/Deserialize-JSON-with-Csharp.aspx
You probably don't want to just declare routes_list as an object type. It doesn't have a .test property, so you really aren't going to get a nice object back. This is one of those places where you would be better off defining a class or a struct, or make use of the dynamic keyword.
If you really want this code to work as you have it, you'll need to know that the object returned by DeserializeObject is a generic dictionary of string,object. Here's the code to do it that way:
var json_serializer = new JavaScriptSerializer();
var routes_list = (IDictionary<string, object>)json_serializer.DeserializeObject("{ \"test\":\"some data\" }");
Console.WriteLine(routes_list["test"]);
If you want to use the dynamic keyword, you can read how here.
If you declare a class or struct, you can call Deserialize instead of DeserializeObject like so:
class MyProgram {
struct MyObj {
public string test { get; set; }
}
static void Main(string[] args) {
var json_serializer = new JavaScriptSerializer();
MyObj routes_list = json_serializer.Deserialize<MyObj>("{ \"test\":\"some data\" }");
Console.WriteLine(routes_list.test);
Console.WriteLine("Done...");
Console.ReadKey(true);
}
}
Using dynamic object with JavaScriptSerializer.
JavaScriptSerializer serializer = new JavaScriptSerializer();
dynamic item = serializer.Deserialize<object>("{ \"test\":\"some data\" }");
string test= item["test"];
//test Result = "some data"
Newtonsoft is faster than java script serializer. ... this one depends on the Newtonsoft NuGet package, which is popular and better than the default serializer.
one line code solution.
var myclass = Newtonsoft.Json.JsonConvert.DeserializeObject<dynamic>(Jsonstring);
Myclass oMyclass = Newtonsoft.Json.JsonConvert.DeserializeObject<Myclass>(Jsonstring);
You can accomplished your requirement easily by using Newtonsoft.Json library. I am writing down the one example below have a look into it.
Class for the type of object you receive:
public class User
{
public int ID { get; set; }
public string Name { get; set; }
}
Code:
static void Main(string[] args)
{
string json = "{\"ID\": 1, \"Name\": \"Abdullah\"}";
User user = JsonConvert.DeserializeObject<User>(json);
Console.ReadKey();
}
this is a very simple way to parse your json.
Here's a simple class I cobbled together from various posts.... It's been tested for about 15 minutes, but seems to work for my purposes. It uses JavascriptSerializer to do the work, which can be referenced in your app using the info detailed in this post.
The below code can be run in LinqPad to test it out by:
Right clicking on your script tab in LinqPad, and choosing "Query
Properties"
Referencing the "System.Web.Extensions.dll" in "Additional References"
Adding an "Additional Namespace Imports" of
"System.Web.Script.Serialization".
Hope it helps!
void Main()
{
string json = #"
{
'glossary':
{
'title': 'example glossary',
'GlossDiv':
{
'title': 'S',
'GlossList':
{
'GlossEntry':
{
'ID': 'SGML',
'ItemNumber': 2,
'SortAs': 'SGML',
'GlossTerm': 'Standard Generalized Markup Language',
'Acronym': 'SGML',
'Abbrev': 'ISO 8879:1986',
'GlossDef':
{
'para': 'A meta-markup language, used to create markup languages such as DocBook.',
'GlossSeeAlso': ['GML', 'XML']
},
'GlossSee': 'markup'
}
}
}
}
}
";
var d = new JsonDeserializer(json);
d.GetString("glossary.title").Dump();
d.GetString("glossary.GlossDiv.title").Dump();
d.GetString("glossary.GlossDiv.GlossList.GlossEntry.ID").Dump();
d.GetInt("glossary.GlossDiv.GlossList.GlossEntry.ItemNumber").Dump();
d.GetObject("glossary.GlossDiv.GlossList.GlossEntry.GlossDef").Dump();
d.GetObject("glossary.GlossDiv.GlossList.GlossEntry.GlossDef.GlossSeeAlso").Dump();
d.GetObject("Some Path That Doesnt Exist.Or.Another").Dump();
}
// Define other methods and classes here
public class JsonDeserializer
{
private IDictionary<string, object> jsonData { get; set; }
public JsonDeserializer(string json)
{
var json_serializer = new JavaScriptSerializer();
jsonData = (IDictionary<string, object>)json_serializer.DeserializeObject(json);
}
public string GetString(string path)
{
return (string) GetObject(path);
}
public int? GetInt(string path)
{
int? result = null;
object o = GetObject(path);
if (o == null)
{
return result;
}
if (o is string)
{
result = Int32.Parse((string)o);
}
else
{
result = (Int32) o;
}
return result;
}
public object GetObject(string path)
{
object result = null;
var curr = jsonData;
var paths = path.Split('.');
var pathCount = paths.Count();
try
{
for (int i = 0; i < pathCount; i++)
{
var key = paths[i];
if (i == (pathCount - 1))
{
result = curr[key];
}
else
{
curr = (IDictionary<string, object>)curr[key];
}
}
}
catch
{
// Probably means an invalid path (ie object doesn't exist)
}
return result;
}
}
As tripletdad99 said
var result = JsonConvert.DeserializeObject<T>(json);
but if you don't want to create an extra object you can make it with Dictionary instead
var result = JsonConvert.DeserializeObject<Dictionary<string, string>>(json_serializer);
add this ddl to reference to your project: System.Web.Extensions.dll
use this namespace: using System.Web.Script.Serialization;
public class IdName
{
public int Id { get; set; }
public string Name { get; set; }
}
string jsonStringSingle = "{'Id': 1, 'Name':'Thulasi Ram.S'}".Replace("'", "\"");
var entity = new JavaScriptSerializer().Deserialize<IdName>(jsonStringSingle);
string jsonStringCollection = "[{'Id': 2, 'Name':'Thulasi Ram.S'},{'Id': 2, 'Name':'Raja Ram.S'},{'Id': 3, 'Name':'Ram.S'}]".Replace("'", "\"");
var collection = new JavaScriptSerializer().Deserialize<IEnumerable<IdName>>(jsonStringCollection);
Copy your Json and paste at textbox on json2csharp and click on Generate button.
A cs class will be generated use that cs file as below
var generatedcsResponce = JsonConvert.DeserializeObject(yourJson);
Where RootObject is the name of the generated cs file;
Another fast and easy way to semi-automate these steps is to:
take the JSON you want to parse and paste it here: https://app.quicktype.io/ . Change language to C# in the drop down.
Update the name in the top left to your class name, it defaults to "Welcome".
In visual studio go to Website -> Manage Packages and use NuGet to add Json.Net from Newtonsoft.
app.quicktype.io generated serialize methods based on Newtonsoft.
Alternatively, you can now use code like:
WebClient client = new WebClient();
string myJSON = client.DownloadString("https://URL_FOR_JSON.com/JSON_STUFF");
var myClass = Newtonsoft.Json.JsonConvert.DeserializeObject(myJSON);
Convert a JSON string into an object in C#. Using below test case.. its worked for me. Here "MenuInfo" is my C# class object.
JsonTextReader reader = null;
try
{
WebClient webClient = new WebClient();
JObject result = JObject.Parse(webClient.DownloadString("YOUR URL"));
reader = new JsonTextReader(new System.IO.StringReader(result.ToString()));
reader.SupportMultipleContent = true;
}
catch(Exception)
{}
JsonSerializer serializer = new JsonSerializer();
MenuInfo menuInfo = serializer.Deserialize<MenuInfo>(reader);
First you have to include library like:
using System.Runtime.Serialization.Json;
DataContractJsonSerializer desc = new DataContractJsonSerializer(typeof(BlogSite));
string json = "{\"Description\":\"Share knowledge\",\"Name\":\"zahid\"}";
using (var ms = new MemoryStream(ASCIIEncoding.ASCII.GetBytes(json)))
{
BlogSite b = (BlogSite)desc.ReadObject(ms);
Console.WriteLine(b.Name);
Console.WriteLine(b.Description);
}
Let's assume you have a class name Student it has following fields and it has a method which will take JSON as a input and return a string Student Object.We can use JavaScriptSerializer here Convert JSON String To C# Object.std is a JSON string here.
public class Student
{
public string FirstName {get;set:}
public string LastName {get;set:}
public int[] Grades {get;set:}
}
public static Student ConvertToStudent(string std)
{
var serializer = new JavaScriptSerializer();
Return serializer.Deserialize<Student>(std);
}
Or, you can use the System.Text.Json library as follows:
using System.Text.Json;
...
var options = new JsonSerializerOptions()
{
PropertyNameCaseInsensitive = true
});
var result = JsonSerializer.Deserialize<List<T>>(json, options);
Where T is your object type that matches your JSON string.
System.Text.Json is available in:
.NET Core 2.0 and above
.NET Framework 4.6.1 and above