I am trying to read json from a local .json file and parse the contents using StreamReader and Json.NET. Json & my code:
contents of .json file: {"rate":50,"information":{"height":70,"ssn":43,"name":"andrew"}}
using (var sr = new StreamReader(pathToJsonFile))
{
dynamic jsonArray = JsonConvert.DeserializeObject(sr.ReadToEnd());
foreach(var item in jsonArray)
{
Console.WriteLine(item.rate);
Console.WriteLine(item.ssn);
}
}
This gives me an error on the line foreach(var item in array): Object reference not set to an instance of an object. I am guessing this is because my json is not actually an array but that is how I am trying to parse it. How can I parse this json in order to pull out fields such as rate or ssn?
NB - please do not flag this question as a duplicate of Read and parse a Json File in C#, as that is where I got my original code from.
EDIT: As has been pointed out in other answers, jsonArray is null. That explains my error but still does not answer my question. How else can I parse this json in order to extract the desired fields?
A couple things:
If you want to manually parse out the values, you should try using JObject rather than JsonConvert.DeserializeObject. The following code should work:
dynamic jsonObject = JObject.Parse("{'rate':50,'information':{'height':70,'ssn':43,'name':'andrew'}}");
Console.WriteLine(jsonObject["rate"]);
Console.WriteLine(jsonObject["information"]["ssn"]);
However, if you know how the json is structured, you should create a .net class like:
public class Person
{
public int rate {get;set;}
public Information information {get;set;}
}
public class Information
{
public int height {get;set;}
public int ssn {get;set;}
public string name {get;set;}
}
and then use:
var person = JsonConvert.DeserializeObject<Person>(thestringtodeserialize);
That way you can have a strongly typed object.
In any case, I would check for null (DeserializeObject can obviously return null):
using (var sr = new StreamReader(pathToJsonFile))
{
dynamic jsonArray = JsonConvert.DeserializeObject(sr.ReadToEnd());
if(jsonArray != null) //new check here
{
foreach(var item in jsonArray)
{
Console.WriteLine(item.rate);
Console.WriteLine(item.ssn);
}
}
I am guessing this is because my json is not actually an array
True, the returned object is dynamic, so make use of dynamic:
var json = "{\"rate\":50,\"information\":{\"height\":70,\"ssn\":43,\"name\":\"andrew\"}}";
dynamic obj = JsonConvert.DeserializeObject(json);
Console.WriteLine("rate: {0}. ssn: {1}", obj.rate, obj.information.ssn);
See live sample here: https://dotnetfiddle.net/nQYuyX
Are you sure it's an array?
If that's the format the you expect from Json, maybe you should consider defining a class.
For example:
class SomeJsonObject
{
public int rate {get;set;}
[JsonProperty("information")] //if you want to name your property something else
public InformationObject Information {get;set;}
}
class InformationObject
{
[JsonProperty("height", NullValueHandling = NullValueHandling.Ignore)] //some other things you can do with Json
public int Height {get;set;}
public int ssn {get;set;}
public string name {get;set;}
}
This way you can just deserialize it to an object:
SomeJsonObject jsonArray = JsonConvert.DeserializeObject<SomeJsonObject>(sr.ReadToEnd());
I think your question is similar to this Deserialize JSON with C# . you can use JavaScriptSerializer
I don't get a null reference (with Json.net 6.0.3) but your code has one obvious bug:
static void Main(string[] args)
{
string s = "{'rate':50,'information':{'height':70,'ssn':43,'name':'andrew'}}".Replace('\'', '\"');
var obj = JsonConvert.DeserializeObject(s);
dynamic jsonArray = obj;
foreach (var item in jsonArray)
{
Console.WriteLine(item.rate);
Console.WriteLine(item.ssn);
}
}
The bug is Console.WriteLine(item.rate) will throw.
Your 'array' jsonArray is not actually an array, it is a dictionary!
Therefore, item=the first Key-Value-pair in the dictionary, = {"rate":50}.
You can prevent the code from throwing by getting rid of your foreach loop.
i would fire up nuget and get the JSON.net package
https://www.nuget.org/packages/Newtonsoft.Json/
http://james.newtonking.com/json
it is well documented and can save you a tonne of work.
see also http://json2csharp.com/
EDIT: you are already using this
Related
I have this json string, which contains two elements each with a Number and a Status:
var jsonString = "{\"Errors\":[{\"Number\":9,\"Status\":\"BadRequest\"}, {\"Number\":3,\"Status\":\"BadConnection\"}]}";
As you see it has a parent property called Errors.
I have prepared this model:
public class ExceptionStructure
{
public int Number { get; set; }
public string Status { get; set; }
}
Using NewtonSoft.Json I would like to deserialize the json string into an array of ExceptionStructure objects, without also having to create a model for the parent property (as I don't really need it).
Can I do this (perhaps with some json attribute on the model class)?
I was hoping to do something like this to deserialize:
var exceptionArr = JsonConvert.DeserializeObject<ExceptionStructure>(jsonString);
JSON.NET allows you to deserialize parts of a json file. You can do this by first deserialzing the json string to a JObject, extract the relevant parts, and then deserialize those to your actual object.
JObject errors = JObject.Parse(jsonString);
IList<JToken> results = errors["Errors"].Children().ToList();
IList<ExceptionStructure> exceptions = new List<ExceptionStructure>();
foreach (JToken result in results)
{
ExceptionStructure exception= result.ToObject<ExceptionStructure>();
exceptions.Add(exception);
}
Honestly though, in your case it might be easier to just build a Errors parent class
More information can be found at http://www.newtonsoft.com/json/help/html/SerializingJSONFragments.htm
this is may be helpful you.
string s = "{\"Errors\":[{\"Number\":9,\"Status\":\"BadRequest\"}, {\"Number\":3,\"Status\":\"BadConnection\"}]}";
var jobj = JObject.Parse(s);
List<ExceptionStructure> list = jobj["Errors"].ToObject<List<ExceptionStructure>>();
OR:
string s = "{\"Errors\":[{\"Number\":9,\"Status\":\"BadRequest\"}, {\"Number\":3,\"Status\":\"BadConnection\"}]}";
List<ExceptionStructure> list = JObject.Parse(s)
.SelectToken("Errors")
.ToObject<List<ExceptionStructure>>();
I have an incoming JSON, which consists array of some objects, say, Foo. I deserialize them with
result = JsonConvert.DeserializeObject<List<Foo>>(message);
Now i want to add a string property to Foo, which will store it's JSON (which i received), so that Foo'll look like:
public class Foo
{
public int MyInt { get; set; }
public bool MyBool { get; set; }
public string JSON { get; set; }
}
But i don't know how can i say JSON.Net the way it can populate such a field..
UPD
I'll clearify what i want. Say i receive JSON:
[{"MyInt":1,"MyBool":0},{"MyInt":2,"MyBool":0},{"MyInt":3,"MyBool":1}]
Here is array of 3 objects and i want, when deserializing, to add corresponding part of json to object, so that:
First object will contain {"MyInt":1,"MyBool":0}
Second object will contain {"MyInt":2,"MyBool":0}
Third object will contain {"MyInt":3,"MyBool":1}
in their JSON Property
I'll be gratefull for any help!
This is one way to do it, but it doesn't maintain the exact original JSON - but it does provide a static record of the original JSON (but without the exact format of the original values - i.e. Bool maybe be 0/1 or true/false):
var message = #"[{""MyInt"":1,""MyBool"":0},{""MyInt"":2,""MyBool"":0},{""MyInt"":3,""MyBool"":1}]";
var foos = JsonConvert.DeserializeObject<List<Foo>>(message);
var t = JsonConvert.SerializeObject(foos[0]);
foos = foos.Select(s => new Foo() { MyBool = s.MyBool, MyInt = s.MyInt, JSON = JsonConvert.SerializeObject(s) }).ToList();
If you are dealing with a lot of Foos, then you might want to find a more efficient way. There might be a way to 'update' using linq, rather than creating a new list.
Okay, i found an answer. I didn't know that i can deserialize message into JArray and then enumerate it (good job, newtonsoft:) ). Here is what i endede up with:
if (tokenType is JArray)
{
var arr = JsonConvert.DeserializeObject(message) as JArray;
foreach (var item in arr)
{
try
{
var agentParameter = item.ToObject<Foo>();
agentParameter.JSON = item.ToString();
result.Add(agentParameter);
}
catch (Exception)
{
LogProvider.Error(string.Format("Failed to Deserialize message. Message text: \r\n {0}", item.ToString()));
}
}
}
I have the following string (json format)
I have gotten from my server:
{[{"ruta": "1","division": "7"},{"ruta": "2","division": "7"},{"ruta": "3","division":"7"},{"ruta": "4","division": "7"},{"ruta": "5","division": "7"},{"ruta": "23","division": "7"}]}
I want to get each value and save them in string variables in order to save them in a data base.
For that I am trying to do as follows:
JArray jarr = JArray.Parse(result);
foreach (JObject content in jarr.Children<JObject>())
{
foreach (JProperty prop in content.Properties())
{
string tempValue = prop.Value.ToString; // This is not allowed
//here more code in order to save in a database
}
}
But I can't find the way to convert the values to string.
Use ToString(), not ToString.
ToString() is a method call; ToString is a reference to the ToString method, and can only be assigned to a compatible delegate.
You can also cast to String, since the JToken class defines a conversion:
string tempValue = (string)prop.Value;
Another option to consider is to use JSON serialization: create a class that represents the JSON data (with the same structure), and deserialize the JSON to this class. It makes the code much more readable and maintainable.
You can directly de serialize your json using C# class(using:- http://json2csharp.com/) and not need to iterate through Json.
public class YourClass
{
public string ruta { get; set; }
public string division { get; set; }
}
You can de serialize
List<YourClass> yourClasslist= JsonConvert.DeserializeObject<List<YourClass>>(result.ToString());
You can do this because your Json is in structured format
JArray jarr = JArray.Parse(result);
foreach (JObject content in jarr.Children<JObject>())
{
foreach (JProperty prop in content.Properties())
{
string tempValue = prop.Value.ToString(); // This is not allowed
//here more code in order to save in a database
}
}
as for the JSON you should start from a JObject since it's surrounded by { }, or remove them from around the JSON you posted in your question
JProperty.Value is of type JToken which has a method ToString (and not a property).
See documentation here.
The syntax should be like that:
string tempValue = prop.Value.ToString();
I'm really bad with C# and would like your help doing the following; I am currently passing a Json Array to my WCF webservice. I need to take the json array and insert it into a list. I have no idea to deserialize in C#. Please suggest to me what is the best way of achieving this. My code looks as follows:
public String UpdateOrderAddress(Stream userInfo)
{
try
{
StreamReader reader = new StreamReader(userInfo);
string JSONdata = reader.ReadToEnd();
if (JSONdata == null)
{
return "null";
}
return JSONdata; // Success !
}
catch (Exception e)
{
return e.ToString();
}
}
This is the data in the string that I get from the reader
[{"date":"2013-02-22 15:30:374:021","id":"1","description":"test","name":"test"},
"date":"2013-02-25 11:56:926:020","id":"2","description":"ghy","name":"fhh"},
"date":"2013-02-25 11:56:248:026","id":"3","description":"ghfm","name":"run"}]
The code you posted doesn't show how are you trying to deserialize your json string so I don't really follow what's the relevance here but in any case, this is how to deserialize JSON into a concrete C# class.
Create a class that matches the structure of your Javascript objects as so:
public class Data
{
public string Date {get;set;}
public int ID {get;set;}
public string Description {get;set;}
public string Name {get;set;}
}
Deserialize it using the JavascriptSerializer as so:
var deserializedData = new JavaScriptSerializer().Deserialize<List<Data>>(jsonString);
Note that your original JSON string is incorrectly formatted. It's missing the opening { on each element of the array. It should really be:
[{"date":"2013-02-22
15:30:374:021","id":"1","description":"test","name":"test"},
{"date":"2013-02-25
11:56:926:020","id":"2","description":"ghy","name":"fhh"},
{"date":"2013-02-25
11:56:248:026","id":"3","description":"ghfm","name":"run"}]
Now, if you attempt to deserialize the above, as so:
string json = #"[{""date"":""2013-02-22 15:30:374:021"",""id"":""1"",""description"":""test"",""name"":""test""},
{""date"":""2013-02-25 11:56:926:020"",""id"":""2"",""description"":""ghy"",""name"":""fhh""},
{""date"":""2013-02-25 11:56:248:026"",""id"":""3"",""description"":""ghfm"",""name"":""run""}]";
var deserializedData = new JavaScriptSerializer().Deserialize<List<Data>>(json);
You'll get a nice List<Data> back.
Also note that I didn't use a DateTime field for the corresponding date field in your Javascript object, the reason being that your sample dates are not valid DateTimes or at least a DateTime object cannot be created from that string representation. For instance, "15:30:374:021" makes no sense - I would imagine that 374 is the seconds field...
You need to add a reference to System.Web.Extensions to be able to use the JavascriptSerializer.
You can create a representative class with your required properties to hold the values and use the JavascriptSerializer class. Call the Deserialize<T> method specifying your type to deserialize the JSON into your code.
Links in class names for reference.
You can use Newtonsoft.Json Library. All you will need to do is:
List<YourClass> yourClassList = JsonConvert.DeserializeObject<List<YourClass>>(JSONdata);
You find more information, even samples here
I'm recieving a JSON object that looks like the example below.
{
"name1":{"name1a":"value1a","name1b":"value1b"},
"name2":{"name2a":"value2a","name2b":"value2b"}
}
I've set up a data contract for it (since I only need to access a single data field at the moment) like this.
[DataContract]
public class MyThingy
{
[DataMember(Name="name1b")]
public string Name1b { get; set; }
public MyThingy() { }
public MyThingy(String name1b)
{
Name1b = name1b;
}
}
When I've serialized the object, I try to print it out (which works, since I'm getting a string description of the class) and them the field Name1b. The last part doesn't work and I'm getting null there. My guess is that I must have mapped the data contract wrongly but I can't see how to correct it.
How should the MyThingy class be declared?
My JSON object is fetched as described in this post.
I would use JavaScriptSerializer here,
string json = #"{
""name1"":{""name1a"":""value1a"",""name1b"":""value1b""},
""name2"":{""name2a"":""value2a"",""name2b"":""value2b""}
}";
var obj = new JavaScriptSerializer()
.Deserialize<Dictionary<string, Dictionary<string, string>>>(json);
Console.WriteLine(obj["name1"]["name1b"]);
You can also use Json.Net and dynamic together
dynamic obj = JsonConvert.DeserializeObject(json);
Console.WriteLine(obj.name1.name1b);