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Deserialize Json an access the result

I have this Json:
{
"UpdatePack":"updatePacks\/1585654836.pack",
"Updates":[
{
"Name":"MsgBoxEx",
"version":"1.5.14.88",
"ChangeLog":"BugFix: Form didn't resize correct.",
"Hash":"5FB23ED83693A6D3147A0485CD13288315F77D3D37AAC0697E70B8F8C9AA0BB8"
},
{
"Name":"Utilities",
"version":"2.5.1.58",
"ChangeLog":"StringManagement updated.",
"Hash":"05E6B3F521225C604662916F50A701E9783E13776DE4FCA27BE4B69705491AC5"
}
]
}
I have created 2 classes to be used to Deserialize it.
class UpdatesList
{
public string Name { get; set; }
public string Version { get; set; }
public string ChangeLog { get; set; }
public string Hash { get; set; }
}
class JsonObjectHolder
{
public string UpdatePack { get; set; }
//public Dictionary<int, MyData> { get; set; }
public Dictionary<int, UpdatesList> Updates { get; set; }
}
But when I try to access the dictionary, I keep getting Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object. at " Console.WriteLine(jsonTest.Dict.Count);"
Am I Deserializing it wrong, or do I need to do some thing else to access the result of the dictionary?
I'm new to both C# and Json.
I hope that some one could point me in the right direction on how to handle this.
I'm using Visual Studio 2019 latest update, and .net 4.8.
Regards
/LR

You code doesn't work because 0 and 1 tokens just a properties, not the array items (you don't have square brackets [] around them). You can parse these values to desired structure manually using JObject
var json = JObject.Parse(your_json_string);
var dict = new Dictionary<int, UpdatesList>();
foreach (var item in json.Properties())
{
if (item.Value.Type == JTokenType.Object)
{
var index = int.Parse(item.Name);
var updateList = item.Value.ToObject<UpdatesList>();
dict.Add(index, updateList);
}
}
var holder = new JsonObjectHolder
{
UpdatePack = json["Updates"]?.Value<string>(),
Dict = dict
};
Update: According to OP changes made to JSON it might be deserialized even more simply
var list = json["Updates"]?.ToObject<List<UpdatesList>>();
var holder = new JsonObjectHolder
{
UpdatePack = json["UpdatePack"]?.Value<string>(),
Dict = list.Select((updatesList, index) => new { updatesList, index })
.ToDictionary(x => x.index, x => x.updatesList)
};
The main point here is that Updates is an array of items, not the key-value collection. It can be transformed into Dictionary<int, UpdatesList> using ToDictionary method from System.Linq (or just use List<UpdatesList> as is)

The exception you're getting essentially means the value is being accessed before the object is initialized.
A better, simpler and cleaner way to doing it is using NewtonSoft. (you can easily get it as a Nuget package)
example:
public class Account
{
public string Email { get; set; }
public bool Active { get; set; }
public DateTime CreatedDate { get; set; }
public IList<string> Roles { get; set; }
}
and then usage:
string json = #"{
'Email': 'james#example.com',
'Active': true,
'CreatedDate': '2013-01-20T00:00:00Z',
'Roles': [
'User',
'Admin'
]
}";
Account account = JsonConvert.DeserializeObject<Account>(json);
Console.WriteLine(account.Email);
Source: https://www.newtonsoft.com/json/help/html/DeserializeObject.htm

I don't see why you need Dictionary<int, UpdatesList> Updates, when you can easily just use List<Update> Updates, since your updates are in a JSON array.
I would model your classes like this:
public class Update
{
public string Name { get; set; }
public string Version { get; set; }
public string ChangeLog { get; set; }
public string Hash { get; set; }
}
public class RootObject
{
public string UpdatePack { get; set; }
public List<Update> Updates { get; set; }
}
You can then deserialize with:
JsonConvert.DeserializeObject<RootObject>(json);
Try it out on dotnetfiddle.net
Note: To convert JSON to C# classes, you can go to Edit -> Paste Special -> Paste JSON as Classes inside Visual Studio. Make sure you have copied the JSON to your clipboard before using it. You will get classes similar to above.

your data and the class is not compatible. if you change the string like this it would work.
change "Updates" to "UpdatePack" and add "Dict" around the dictionary items.
{
"UpdatePack":"updates\/4D1D7964D5B88E5867324F575B77D2FA.zip",
"Dict":{
"0":{
"Name":"MsgBoxEx",
"Version":"1.0.123.58",
"ChangeLog":"Bugfix:Form didn't resize correct",
"hash":"AA94556C0D2C8C73DD217974D252AF3311A5BF52819B06D179D17672F21049A6"
},
"1":{
"Name":"Utilities",
"Version":"1.5.321.87",
"ChangeLog":"StringManagement updated",
"hash":"2F561B02A49376E3679ACD5975E3790ABDFF09ECBADFA1E1858C7BA26E3FFCEF"
}
}
}

Send a post request in JSON format

Below is the format of post request expected in JSON. Can anyone please tell me how to achieve this.
{
"MywebServiceInputDetail":{
"MyDatalst":{
"MyData":[
{
"name":"TestName",
"id":"2611201",
"SomeRefVal":"REF123456"
}
]
}
}
}
I am using JavaScriptSerializer as of now.
Below is the code.
[Serializable]
public struct MyStruct
{
public string name;
public string id;
public string refno;
}
JavaScriptSerializer jss = new JavaScriptSerializer();
string serializedJson = jss.Serialize(ObjMystrcut);
Above code results in the JSON string as
{"name":"TestName","id":"1234567","refno":"567123"}
I am new to JSON so I'm not able to formulate the request format.
I am avoiding to achieve it by hardcoding a json string. Basically, I am trying to understand what does { and [ bracketing mean. Does [ mean that I need to create an array of objects?

You can do something like this:
string serializedJson = jss.Serialize(new { MywebServiceInputDetail = new { MyDatalst = new { MyData = new[] { ObjMystrcut } } } });
{} is object notation, so it represents an object, with properties.
[] is an array notation.

Yes, the [ and ] symbols represent JSON arrays (collections of objects). In your example, MyData is a collection of those structs you created.
You need to create the following classes:
public class MywebServiceInputDetail
{
public MyDatalst MyDatalst { get; set; }
}
public class MyDatalst
{
public List<MyStruct> MyData { get; set; }
}
public struct MyStruct
{
public string name;
public string id;
public string SomeRefVal;
}
Now create a MywebServiceInputDetail object and serialize it.
Personally I would forget about using a struct and just create the following class instead:
public class MyClass
{
public string Name { get; set; }
public string Id { get; set; }
public string SomeRefVal { get; set; }
}
You should also add JSON attributes to the properties to make sure Name and Id are serialized with lowercase letters.

deserializing json to c# object

my C# is not well but I want to deserializing this my json file to C# object:
[
{
"command":"",
"name":"eee",
"children":
[
{
"command":"Report",
"name":"x",
"children":[],
"path":"wwwwww",
"params":
{
"PeriodType":"1i",
"District":"0i"
}
},...
],
"path":"",
"params":{}
},...
for this schema I have created this object:
[DataContract]
public class ListCommands
{
[DataMember]
public List<Commands> commandList { get; set; }
[DataContract]
public class Commands
{
[DataMember]
public string command { get; set; }
[DataMember]
public string name { get; set; }
[DataMember]
public string path { get; set; }
[DataMember(Name = "params")]
public Params parameters { get; set; }
[DataMember]
public List<Commands> children { get; set; }
}
}
}
and :
public class Params
{
[DataMember]
public string PeriodType { get; set; }
[DataMember]
public string District { get; set; }
}
}
and I am using this code for deserializing json to c# object:
public static void ReadJsonFile()
{
ListCommands comList = new ListCommands();
//List<Commands> comList = new List<Commands>();
string root = HttpContext.Current.Server.MapPath("~/File");
using (FileStream stream = File.OpenRead(root + "\\commands.json"))
comList = (ListCommands)new DataContractJsonSerializer(typeof(ListCommands)).ReadObject(stream);
}
}
but unfortunately I got this error:
Additional information: There was an error deserializing the object of type Notifications.Contracts.ListCommands. Encountered unexpected character 'ï'.
Where is the problem?I have a json file and I want to read this file and then convert to the c# object.

The data format for deserialization differs.
Change json data.
{
"commandList":[
{
"command":"",
"name":"eee",
"children":
[
{
"command":"Report",
"name":"x",
"children":[],
"path":"wwwwww",
"params":
{
"PeriodType":"1i",
"District":"0i"
}
}
],
"path":"",
"params":{}
}]
}
or 2. Change the deserialization target type
comList.commandList = (List<ListCommands.Commands>)new DataContractJsonSerializer(typeof(List<ListCommands.Commands>)).ReadObject(stream);

According suggestion of #SirRufo
1- I have used of Json.Net in this way:
string root = HttpContext.Current.Server.MapPath("~/File");
FileStream stream = File.OpenRead(root + "\\commands.json");
StreamReader reader = new StreamReader(stream);
var comList = JsonConvert.DeserializeObject<dynamic>(reader.ReadToEnd());
and above error gone.
2- By this link I could run previously code:
enter link description here
One of the reasons for this could be that the input file that contains the JSON-encoded data is created with a binary encoding or it has a Byte Order Mark(BOM) byte sequence for a binary encoded file.
For e.g. The UTF-8 representation of the BOM is the byte sequence (0xEF,0xBB,0xBF) in the beginning of the file.
**Note:** You will see this if you created a .JSON file(or a binary file) using visual studio.

json newtonsoft : Deserialize Object containing a list of string

I have the following issue with this json :
{
"EVTS": {
"EVT": [
{ "ID": "123456",
"KEY1" : "somekey",
"CATEG": [
"cat1",
"cat2",
"cat3"
]
}
]}
}
and this c# class:
public class myClass{
public string ID { get; set; }
public string KEY1 { get; set; }
public list<string> CATEG { get; set; }
}
public class ESObject1
{
[JsonProperty("EVT")]
public List<myClass> EVT { get; set; }
}
public class ESObject0
{
[JsonProperty("EVTS")]
public ESObject1 EVTS { get; set; }
}
}
here i call the deserializer :
ESObject0 globalobject = JsonConvert.DeserializeObject<ESObject0>(json);
But this last code doesnt work, i throws this exception : System.ArgumentException: Could not cast or convert from System.String to System.Collections.Generic.List1[System.String].`
Instead of list<string> i used string [] and only string nothing seems to work.
how can i deserialize this object correctly please.
Thank you.

There doesn't seem to be any apparent problem wit hyour code as this working example illustrates:
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
public class myClass
{
public string ID { get; set; }
public string KEY1 { get; set; }
public List<string> CATEG { get; set; }
}
public class ESObject1
{
[JsonProperty("EVT")]
public List<myClass> EVT { get; set; }
}
public class ESObject0
{
[JsonProperty("EVTS")]
public ESObject1 EVTS { get; set; }
}
class Program
{
static void Main()
{
string json =
#"{
""EVTS"": {
""EVT"": [
{
""ID"": ""123456"",
""KEY1"": ""somekey"",
""CATEG"": [
""cat1"",
""cat2"",
""cat3""
]
}
]
}
}";
ESObject0 globalobject = JsonConvert.DeserializeObject<ESObject0>(json);
foreach (string item in globalobject.EVTS.EVT[0].CATEG)
{
Console.WriteLine(item);
}
}
}
Maybe you just fed a wrong json value to the deserializer which doesn't look like as the one shown in your question. By the way, the one shown i nyour question is invalid JSON as you are missing a , after KEY1 property declaration.
UPDATE:
Now that you have shown your real JSON (coming from http://donnees.ville.quebec.qc.ca/Handler.ashx?id=69&f=JSON) it appears that there's a row where CATEG is not an array of strings but a simple string:
""CATEG"": ""Conférence""
Now that's a pretty bad design because they are mixing arrays and simple properties. I am afraid that in order to deal with this situation you will need to use JObjects and extract the information you need by testing the actual underlying type.
For example:
var obj = JObject.Parse(json);
var events = (JArray)obj["EVTS"]["EVT"];
foreach (JObject evt in events)
{
var categories = evt["CATEG"];
if (categories is JArray)
{
// you've got a list of strings so you can loop through them
string[] cats = ((JArray)categories)
.Select(x => x.Value<string>())
.ToArray();
}
else
{
// you've got a simple string
string cat = categories.Value<string>();
}
}

I have done this many times with many many headaches. My advice is take the json output and use a tool similar to this to write your class for you (http://json2csharp.com/).
Then go over any nullable variables and add nullable type (ex. using int? for int) where needed.

How do I deserialize a custom node in Json to c#, whose name keeps changing?

Below is a section of json I receive from an endpoint.
If you look at the Json below, 'User-Defined-Network-Name' is a custom node and the name will change each time.
How do I define a C# object for this Json?
"addresses": {
"public": [{
"version": 6,
"address": "2005:4600:788e:0910:1a72:81c0:ff03:c7y6"
},
{
"version": 4,
"address": "197.68.xx.xxx"
}],
"private": [{
"version": 4,
"address": "10.xx.xx.xxx"
}],
"User-Defined-Network-Name": [{
"version": 4,
"address": "192.xxx.x.xxx"
}]
}
This is how far I have come -
[Serializable]
public class Addresses
{
public List<Public> #public { get; set; }
public List<Private> #private { get; set; }
}
Im using 'JavascriptSerializer' class to deserialize json.
Thanks,
Ryan

addresses can be deserialized to a type like Dictionary<string,List<YourClass>> where YourClass holds version and addresss.
var obj = new JavaScriptSerializer().Deserialize<Root>(jsonstring);
--
public class Root
{
public Dictionary<string,List<VersionAddress>> addresses;
//Your other fields/properties
}
public class VersionAddress
{
public string version;
public string address;
}

You could take advantage of the dynamic nature of C#:
// this could come from user input:
string userDefinedName = "User-Defined-Network-Name";
    string json = "YOUR JSON COMES HERE";
var serializer = new JavaScriptSerializer();
dynamic result = serializer.DeserializeObject(json);
int version = result["addresses"][userDefinedName][0]["version"];
string address = result["addresses"][userDefinedName][0]["address"];
Console.WriteLine(version);
Console.WriteLine(address);
and if you wanted to loop through the results:
foreach (dynamic item in result["addresses"][userDefinedName])
{
int version = item["version"];
string address = item["address"];
Console.WriteLine(version);
Console.WriteLine(address);
}

Why don't you make network names a dictionary, with key of network name ?
Then you can just iterate over it.

I would not recommend using JavaScriptSerializer, as it has been deprecated. If you want a third-party solution, JSON.Net is pretty good from what I hear.
However, I'm one that's weird about dependencies, so I typically roll my own if it doesn't exist already. Fortunately, this one isn't too hard due to DataContractJsonSerializer from the System.Runtime.Serialization namespace.
All you need to do is first define all the objects in a nested fashion:
using System.Reflection;
using System.Runtime.Serialization; // You will have to add a reference
using System.Runtime.Serialization.Json; // to System.Runtime.Serialization.dll
[DataContract]
public class AddressInfo
{
[DataMember(Name = "address")]
public string Address { get; set; }
[DataMember(Name = "version")]
public int Version { get; set; }
}
[DataContract]
public class AddressList
{
[DataMember(Name = "public")]
public IEnumerable<AddressInfo> Public { get; set; }
[DataMember(Name = "private")]
public IEnumerable<AddressInfo> Private { get; set; }
[DataMember(Name = "User-Defined-Network-Name")]
public IEnumerable<AddressInfo> UserDefined { get; set; }
}
Then a couple helper methods to do the deserialization:
// This will change the DataMember.Name at runtime!
// This will only work if you know the node name in advance.
static void SetUserDefinedNodeName(string userDefinedNodeName)
{
var type = typeof(AddressList);
var property = type.GetProperty("UserDefined", BindingFlags.Default);
var attribute = property.GetCustomAttribute<DataMemberAttribute>();
if (attribute != null)
attribute.Name = userDefinedNodeName;
}
static T Deserialize<T>(string jsonText, string userDefinedNodeName)
{
SetUserDefinedNodeName(userDefinedName);
var jsonBytes = Encoding.UTF8.GetBytes(jsonText);
using (var stream = new MemoryStream(jsonBytes))
{
var serializer = new DataContractJsonSerializer(typeof(T));
var obj = serializer.ReadObject(stream) as T;
return obj;
}
}
Then you use it like so:
var jsonText = // get your json text somehow
var addressList = Deserialize<AddressList>(jsonText);