Develop Reference

Convert JSON containing `\u####` to Unicode string

I would need some help for a string conversion from unicode (\u03a9\u039c\u0395\u0393\u0391) to normal string (ΩΜΕΓΑ).
I made a function that theoretically should work but it doesn't work instead. I don't understand what I'm doing wrong.
I receive json data with webclient.DownloadString:
{"id": "94401626335", "username": "\u03a9\u039c\u0395\u0393\u0391"}
I get the \u03a9\u039c\u0395\u0393\u0391 and send it to the function:
DecodeFromUtf8(username)
public string DecodeFromUtf8(string utf8String)
{
try
{
var output = WebUtility.HtmlDecode(utf8String);
return output;
}
catch (Exception ex)
{
return utf8String;
}
}
the function always returns me: \u03a9\u039c\u0395\u0393\u0391
and not: ΩΜΕΓΑ
Why?
i can't use external libraries like system.text.json
Thanks

use a json deserializer , let it do the work
public class Ooo {
public string id { get; set; }
public string username { get; set; }
}
var json = #"{""id"": ""94401626335"", ""username"": ""\u03a9\u039c\u0395\u0393\u0391""}";
var ooo = System.Text.Json.JsonSerializer.Deserialize<Ooo>(json) ;
Console.WriteLine("string = " + ooo.username);
}
gives (my console has a glyph misssing, but its show correctly in the debugger)

Serializing and deserializing a collection of objects

I'm trying to create an Rssfeed reader which saves info about a podcast to a JSON file and I'm having trouble serializing and deserializing to that file.
I realize that there are other threads regarding this subject, but I cannot grasp or comprehend how to apply it to my code or the reasoning behind it.
So I have a bit of code that creates a file if it doesn't exist and writes JSON data to it which looks like:
public void SaveFile(Podcast podcast)
{
try
{
JsonSerializer serializer = new JsonSerializer();
if(!File.Exists(#"C: \Users\Kasper\Desktop\Projektuppgift\Projektuppgift - Delkurs2\Projektet\Projektet\bin\Debug\podcasts.json"))
{
string json = JsonConvert.SerializeObject( new { Podcast = podcast });
StreamWriter sw = File.CreateText(#"C:\Users\Kasper\Desktop\Projektuppgift\Projektuppgift-Delkurs2\Projektet\Projektet\bin\Debug\podcasts.json");
using (JsonWriter writer = new JsonTextWriter(sw))
{
serializer.Serialize(writer, json);
}
}
else
{
var filepath = #"C:\Users\Kasper\Desktop\Projektuppgift\Projektuppgift-Delkurs2\Projektet\Projektet\bin\Debug\podcasts.json";
var jsonData = File.ReadAllText(filepath);
var podcasts = JsonConvert.DeserializeObject<List<Podcast>>(jsonData) ?? new List<Podcast>();
podcasts.Add(podcast);
jsonData = JsonConvert.SerializeObject(new {PodcastList = podcasts });
File.WriteAllText(filepath, jsonData);
}
}
catch (Exception ex)
{
Console.WriteLine("IO Exception ", ex.Message);
}
}
What I can't get to work is to deserialize from this file and add an object to it. Is there an easier way to add more data to the JSON file or am I missing something?
The Podcast class looks like this:
public class Podcast
{
public string url { get; set; }
public string name { get; set; }
public int updateInterval { get; set; }
public string category { get; set; }
//public Category category = new Category();
public List<Episode> episodes { get; set; }
public Podcast(string url, string name, Category category, List<Episode> episodes, int updateInterval)
{
this.url = url;
this.name = name;
this.category = category.name;
this.episodes = episodes;
this.updateInterval = updateInterval;
}
public Podcast(Podcast p)
{
this.url = p.url;
this.name = p.name;
this.category = p.category;
this.episodes = p.episodes;
this.updateInterval = p.updateInterval;
}
}

There appear to be a couple of issues here:
You are checking for the existence of a different file than the one you are reading/writing. The former filename has extra spaces in it. The best way to avoid this problem is to use a variable to contain the filename rather than hardcoding it in three separate places.
You are inconsistent about the JSON format you are writing and reading:
When you first create the file (in the first branch), you are writing a JSON object that contains a property Podcast which then contains a single podcast.
When you attempt to read the JSON file, you are treating the entire JSON as a list of podcasts.
After tacking the new podcast onto the list, you are writing the JSON as a single object containing a PodcastList property, which then contains the list.
You need to use a consistent JSON format. I would recommend breaking your code into smaller methods to read and write the podcasts.json file like this so that it is easier to reason about:
public static List<Podcast> ReadPodcastsFromFile(string filepath)
{
if (!File.Exists(filepath)) return new List<Podcast>();
string json = File.ReadAllText(filepath);
return JsonConvert.DeserializeObject<List<Podcast>>(json);
}
public static void WritePodcastsToFile(List<Podcast> podcasts, string filepath)
{
string json = JsonConvert.SerializeObject(podcasts);
// This will overwrite the file if it exists, or create a new one if it doesn't
File.WriteAllText(filepath, json);
}
Then, you can simplify your SaveFile method down to this (I would be tempted to rename it to SavePodcast):
public void SaveFile(Podcast podcast)
{
var filepath = #"C:\Users\Kasper\Desktop\Projektuppgift\Projektuppgift-Delkurs2\Projektet\Projektet\bin\Debug\podcasts.json";
List<Podcast> podcasts = ReadPodcastsFromFile(filepath);
podcasts.Add(podcast);
WritePodcastsToFile(podcasts, filepath);
}
Notice I've also removed the exception handling from SaveFile. You should move that up to wherever SaveFile is called, so that you can take appropriate action at that point if an exception is thrown, e.g.:
try
{
SaveFile(podcast);
}
catch (Exception ex)
{
// Show a message to the user indicating that the file did not save
}

I'm just still learning c# but it might be that you deserialise into a list of podcasts and when you serialise you're serliasing into an object type.

Get JSON Data in variable when only one item is returned

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

How to set status to Json array .net?

I have a webservice that returns json array (JArray) in string format, but I do not understand how to add state value to that operation and get it in the application that consumes the service.
My question is, should I return a json object with a message and inside a json array? Or just an array? hich is more convenient ?
my ws:
public string getList(string strSalary)
{
List<Employee> listJson = null;
JObject jsonResp = "";
JArray array = null;
try
{
listJson = ReportBLL.getInstance.listEmployees(int.Parse(strSalary));
array = JArray.FromObject(listJson);
//set array status ?: ej
//array status = "succes";
}
catch (Exception ex)
{
//set error message
// array status = "error";
//array message = ex.Message or "Not found employees";
}
return JsonConvert.SerializeObject(array);
}
client call (other asp app):
public static List<Employee> listEmployeeClient(string salary)
{
JObject jo = null; //or arrayjson ?
string strData = "";
strData = webService.getList(salary);
jo = JObject.Parse(strData);
//how to evalue status request ?
/* example
if(jo.status == "error") {
throw new Exception(jo.message);
} else {
iterate array inside json object ?
}
*/
}
Is this logic correct ?

You can create a new entity for API Response and use it for all your API responses, You can test it out by the following example.
In server:
Class APIResponse<T>
{
public bool IsError;
public int ErrorCode;
public string ErrorMessage;
public T ReponseData;
}
public string getList(string strSalary)
{
List<Employee> listJson = null;
APIResponse<Employee> responseString = new APIResponse<Employee>();
try
{
listJson = ReportBLL.getInstance.listEmployees(int.Parse(strSalary));
responseString.isError = false;
responseString.data = JArray.FromObject(listJson);
}
catch (Exception ex)
{
responseString.IsError = true;
responseString.ErrorCode = 404; //You can add custom error codes
responseString.ErrorMessage = ex;
}
return JsonConvert.SerializeObject(responseString);
}
In Client:
public static List<Employee> listEmployeeClient(APIResponse<Employee> salary)
{
//You can access the model here
}

There are many options. If you have REST apis you can use the HTTPStatusCodes, for each request, e.g. 200 for OK, 400 bad request, etc.
If you want more fine tuning, you can have a general structure of your response objects, e.g.
responseDto:
status: any code, error or success
message: any error message
data: any expected data

use a Dictionary<string,object> before serializing, and use dynamic to conveniently get the various fields after deserializing. jArray.ToObject<List<Employee>>() will convert JArray object back to the proper type.
Example below:
class Employee
{
public string Name { get; set; }
}
// serializing
var employees = new List<Employee>()
{
new Employee() {Name = "john"},
new Employee() {Name = "alex"},
new Employee() {Name = "susan"},
new Employee() {Name = "bryan"},
};
var dict = new Dictionary<string, object>
{
["employees"] = employees,
["status"] = "error",
["errormessage"] = "Not found employees"
};
var json = JsonConvert.SerializeObject(dict);
// deserializing
dynamic deserialized = JsonConvert.DeserializeObject(json);
string status = deserialized.status;
string errorMessage = deserialized.errormessage;
JArray jArray = deserialized.employees;
List<Employee> deserializedEmployee = jArray.ToObject<List<Employee>>();

Is there a simpler way to return fields from static function?

I often want to parse a string into various bits and have a readable way to return them.
I like this approach, but it involves creating a specific class
long orderID = Utils.UnTradeIdent(tradeIdent).OrderID;
In Utils.cs:
public class TradeIdentData
{
public string AccountIdent;
public long OrderID;
public string SubID;
}
public static TradeIdentData UnTradeIdent(string tradeIdent)
{
TradeIdentData tradeIdentData = new TradeIdentData();
var parts = tradeIdent.Split('!');
tradeIdentData.AccountIdent = parts[0];
if (parts[1].Contains("."))
{
var bits = parts[1].Split('.');
tradeIdentData.OrderID = long.Parse(bits[1]);
tradeIdentData.SubID = bits[1];
}
else
{
tradeIdentData.OrderID = long.Parse(parts[1]);
tradeIdentData.SubID = "";
}
return tradeIdentData;
}

A separate class with well-named properties (which you are already using) is currently the most readable way of doing this.
In C# 7 you will be able to use tuples for return values, like so:
public static (string AccountIdent, string OrderID, string SubID) UnTradeIdent(string tradeIdent)
{
string accountIdent, orderID, subID ;
... Code to initialise accountIdent, orderID and subID appropriately ...
// Now return the data as a tuple:
return (accountIdent, orderID, subID);
}
You can consume this as follows:
long orderID = Utils.UnTradeIdent(tradeIdent).OrderID;
Or if you want all the values:
var result = Utils.UnTradeIdent(tradeIdent);
// Use result.OrderId, result.SubID or result.AccountIdent
This is not going to be available until some time next year, though.
Also, even though this new tuple support makes it more convenient to WRITE the code, it doesn't let you document it using XML comments as well. Spending the time to write a simple and well-documented class will still often be better than using the new C# 7 tuple support.
See here for more details.

You can also use the out keyword to pass arguments by reference, see MSDN article out (C# Reference):
public static void UnTradeIdent(string tradeIdent, out string AccountIdent, out long OrderID, out string SubID)
{
var parts = tradeIdent.Split('!');
AccountIdent = parts[0];
if (parts[1].Contains("."))
{
var bits = parts[1].Split('.');
OrderID = long.Parse(bits[1]);
SubID = bits[1];
}
else
{
OrderID = long.Parse(parts[1]);
SubID = "";
}
}
UPDATED with suggestion from comments:
public static bool UnTradeIdent(string tradeIdent, out string AccountIdent, out long OrderID, out string SubID)
{
bool result = false;
AccountIdent = "";
OrderID = 0;
SubID = "";
try
{
var parts = tradeIdent.Split('!');
AccountIdent = parts[0];
if (parts[1].Contains("."))
{
var bits = parts[1].Split('.');
OrderID = long.Parse(bits[1]);
SubID = bits[1];
}
else
{
OrderID = long.Parse(parts[1]);
SubID = "";
}
}
catch(ArgumentNullException ane)
{
// Handle parsing exception
}
catch (FormatException fe)
{
// Handle parsing exception
}
catch (OverflowException oe)
{
// Handle parsing exception
}
return result;
}

Its pretty simple to do just by changing the return type to dynamic and using an anonymous class
public static dynamic UnTradeIdent(string tradeIdent)
{
var value1 = //parselogic
var value2 = //parselogic
return new { Identity = value1, Item2 = value2};
}

I would consider making additional static methods. Your current implementation is cleaner when you require all of the returned properties, but something like below might be appropriate when you only need one of them.
public static string TradeIdentToAccountIdent(string tradeIdent)
{
var parts = tradeIdent.Split('!');
return parts[0];
}
public static long TradeIdentToOrderID(string tradeIdent)
{
var parts = tradeIdent.Split('!');
if (parts[1].Contains("."))
{
var bits = parts[1].Split('.');
return long.Parse(bits[1]); // Taken from your example, should probably be bits[0]?
}
else
return long.Parse(parts[1]);
}
// My own take on it this time, you could obviously use your logic as well.
public static string TradeIdentToSubID(string tradeIdent)
{
var order = tradeIdent.Split('!')[1];
if (order.Contains("."))
return order.Split('.')[1];
else
return String.Empty;
}