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Getting a specific field from a JSON string without deserializing in C#

I currently have a REST app which returns a JSON string something like:
[{error: "Account with that email exists"}]
For when an error is thrown. I don't want to deserialize it into a custom "error" object, because it seems a bit wasteful and pointless. Is there a simple way to just extract a specific field out of a JSON string without making a custom class to reflect it.
Thanks

You have a couple of options if you don't want to create a custom class, you can deserialize to dynamic:
dynamic tmp = JsonConvert.DeserializeObject(yourString);
string error = (string)tmp.error;
Or deserialize to a dictionary:
var dic = JsonConvert.DeserializeObject<Dictionary<string, string>>();
string error = dic["error"];

No need third party libraries. Use native JavaScriptSerializer.
string input = "[{error: \"Account with that email exists\"}]";
var jss = new JavaScriptSerializer();
var array = jss.Deserialize<object[]>(input);
var dict = array[0] as Dictionary<string, object>;
Console.WriteLine(dict["error"]);
// More short with dynamic
dynamic d = jss.DeserializeObject(input);
Console.WriteLine(d[0]["error"]);

Have a look at JObject.
dynamic obj = JObject.Parse("{ myerrors: [{error: \"Account with that email exists\"}] }");
var a = obj.myerrors[0];
string error = a.error;

Convert Stream object to json object and then to user defined object

I call a service function which returns me a stream.
The stream contains an JSON object with two properties (Url and Status).
I want want to convert this JSON object into my user defined class called 'Response'. Response class has two properties Url and Status.
The code I have so far, but unclear what to do next or if I need to implement something else:
var response = _service.GetObject("Create");
var serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
var jsonObject = serializer.DeserializeObject(response.ReadToEnd());

You can use the overload which takes a T generic type parameter and internally casts to the desired type:
Response jsonObject = serializer.DeserializeObject<Response>(response.ReadToEnd());
Note JavaScriptSerializer is deprecated. You should use Json.NET to work with JSON, which has the equivalent:
var response = _service.GetObject("Create");
var serializer = JsonConvert.DeserializeObject<Response>(response.ReadToEnd());

how to deserialize an anonymus object in c# [duplicate]

Is it possible to return a dynamic object from a json deserialization using json.net? I would like to do something like this:
dynamic jsonResponse = JsonConvert.Deserialize(json);
Console.WriteLine(jsonResponse.message);

Json.NET allows us to do this:
dynamic d = JObject.Parse("{number:1000, str:'string', array: [1,2,3,4,5,6]}");
Console.WriteLine(d.number);
Console.WriteLine(d.str);
Console.WriteLine(d.array.Count);
Output:
1000
string
6
Documentation here: LINQ to JSON with Json.NET
See also JObject.Parse and JArray.Parse

As of Json.NET 4.0 Release 1, there is native dynamic support:
[Test]
public void DynamicDeserialization()
{
dynamic jsonResponse = JsonConvert.DeserializeObject("{\"message\":\"Hi\"}");
jsonResponse.Works = true;
Console.WriteLine(jsonResponse.message); // Hi
Console.WriteLine(jsonResponse.Works); // True
Console.WriteLine(JsonConvert.SerializeObject(jsonResponse)); // {"message":"Hi","Works":true}
Assert.That(jsonResponse, Is.InstanceOf<dynamic>());
Assert.That(jsonResponse, Is.TypeOf<JObject>());
}
And, of course, the best way to get the current version is via NuGet.
Updated (11/12/2014) to address comments:
This works perfectly fine. If you inspect the type in the debugger you will see that the value is, in fact, dynamic. The underlying type is a JObject. If you want to control the type (like specifying ExpandoObject, then do so.

If you just deserialize to dynamic you will get a JObject back. You can get what you want by using an ExpandoObject.
var converter = new ExpandoObjectConverter();
dynamic message = JsonConvert.DeserializeObject<ExpandoObject>(jsonString, converter);

I know this is old post but JsonConvert actually has a different method so it would be
var product = new { Name = "", Price = 0 };
var jsonResponse = JsonConvert.DeserializeAnonymousType(json, product);

Yes you can do it using the JsonConvert.DeserializeObject. To do that, just simple do:
dynamic jsonResponse = JsonConvert.DeserializeObject(json);
Console.WriteLine(jsonResponse["message"]);

Note: At the time I answered this question in 2010, there was no way to deserialize without some sort of type, this allowed you to deserialize without having go define the actual class and allowed an anonymous class to be used to do the deserialization.
You need to have some sort of type to deserialize to. You could do something along the lines of:
var product = new { Name = "", Price = 0 };
dynamic jsonResponse = JsonConvert.Deserialize(json, product.GetType());
My answer is based on a solution for .NET 4.0's build in JSON serializer. Link to deserialize to anonymous types is here:
http://blogs.msdn.com/b/alexghi/archive/2008/12/22/using-anonymous-types-to-deserialize-json-data.aspx

If you use JSON.NET with old version which didn't JObject.
This is another simple way to make a dynamic object from JSON:
https://github.com/chsword/jdynamic
NuGet Install
PM> Install-Package JDynamic
Support using string index to access member like:
dynamic json = new JDynamic("{a:{a:1}}");
Assert.AreEqual(1, json["a"]["a"]);
Test Case
And you can use this util as following :
Get the value directly
dynamic json = new JDynamic("1");
//json.Value
2.Get the member in the json object
dynamic json = new JDynamic("{a:'abc'}");
//json.a is a string "abc"
dynamic json = new JDynamic("{a:3.1416}");
//json.a is 3.1416m
dynamic json = new JDynamic("{a:1}");
//json.a is integer: 1
3.IEnumerable
dynamic json = new JDynamic("[1,2,3]");
/json.Length/json.Count is 3
//And you can use json[0]/ json[2] to get the elements
dynamic json = new JDynamic("{a:[1,2,3]}");
//json.a.Length /json.a.Count is 3.
//And you can use json.a[0]/ json.a[2] to get the elements
dynamic json = new JDynamic("[{b:1},{c:1}]");
//json.Length/json.Count is 2.
//And you can use the json[0].b/json[1].c to get the num.
Other
dynamic json = new JDynamic("{a:{a:1} }");
//json.a.a is 1.

Yes it is possible. I have been doing that all the while.
dynamic Obj = JsonConvert.DeserializeObject(<your json string>);
It is a bit trickier for non native type. Suppose inside your Obj, there is a ClassA, and ClassB objects. They are all converted to JObject. What you need to do is:
ClassA ObjA = Obj.ObjA.ToObject<ClassA>();
ClassB ObjB = Obj.ObjB.ToObject<ClassB>();

Serialize string to JSON without \0027

A fairly straightforward question. I have the following code
var json = new JavaScriptSerializer();
var test = json.Serialize("'");
Now, Visual Studio local variable watch shows that test contains a string of value "\"\\u0027\"". Is it possible, using build in ASP.NET to make Serialize(); return serialized string without \0027 format?
The desired result for test would be "\"\'\""
Thanks!

As the commenters mentioned, this really shouldn't matter because \u0027 literally represents a single quote in Javascript.
However, if this bothers you, you may want to try using JSON.NET, which leaves single-quotes in encoded strings as they are.

Try the following
var json = JsonConvert.SerializeObject(obj);

You have to use this expression to replace your JSON string after it's serialized. Here is a sample of my code along with a function I use when giving a json output.
string json = obj.ToJSON();
json = System.Text.RegularExpressions.Regex.Unescape(json);
File.WriteAllText("<DirectoryFile>.json", json);
public static string ToJSON(this object obj)
{
var serializer = new JavaScriptSerializer();
serializer.MaxJsonLength = Int32.MaxValue;
JavaScriptSerializer js = new JavaScriptSerializer();
return js.Serialize(obj);
}

JObject how to read values in the array?

This is the json string:
{"d":[{"numberOfRowsAdded":"26723"}]}
string json = DAO.getUploadDataSummary();
JObject uploadData = JObject.Parse(json);
string array = (string)uploadData.SelectToken("d");
How do I change the code to reader the values in 'numberOfRowsAdded?

JObject uploadData = JObject.Parse(json);
int rowsAdded = Convert.ToInt32((string)uploadData["d"][0]["numberOfRowsAdded"])

You need to cast to JArray:
string json = "{\"d\":[{\"numberOfRowsAdded\":\"26723\"}]}";
JObject parsed = JObject.Parse(json);
JArray array = (JArray) parsed["d"];
Console.WriteLine(array.Count);

You can cast your JObject as a dynamic object.
You can also cast your array to JArray object.
JObject yourObject;
//To access to the properties in "dot" notation use a dynamic object
dynamic obj = yourObject;
//Loop over the array
foreach (dynamic item in obj.d) {
var rows = (int)item.numberOfRowsAdded;
}

I played around with writing a generic method that can read any part of my json string. I tried a lot of the answers on this thread and it did not suit my need. So this is what I came up with. I use the following method in my service layer to read my configuration properties from the json string.
public T getValue<T>(string json,string jsonPropertyName)
{
var parsedResult= JObject.Parse(json);
return parsedResult.SelectToken(jsonPropertyName).ToObject<T>();
}
and this is how you would use it :
var result = service.getValue<List<string>>(json, "propertyName");
So you can use this to get specific properties within your json string and cast it to whatever you need it to be.