We Keep Coding

How can i convert an array in Json string to c# object?

I have a json return result like the following:
Json =
{
"Id":"12345",
"FirstName":"Bob",
"LastName":"Builder",
"Links":[]
}
Links can have a list of objects of type LinkService, i want to cast even if the array is empty , so in c# i get an empty array.
I do the following
var token = JObject.Parse(Json);
var Id = token.Value<string>("Id");
var fname = token.Value<string>("FirstName");
var lbname = token.Value<bool>("LastName");
var links = JsonSerializer.Deserialize<List<LinkService>>(token.Value<Array>("Links"));
Issue is that it says cant convert System.Array to Newtonsoft.Json.JsonReader

You can convert the jToken to an object using the ToObject method:
var links = token["Links"].TObject<List<LinkService>>();

Dynamic variable not working in C# with Json.Net

Can anyone tell me why I get an error when trying to output"dJson2.Type" in the code below?
string Json1= #"[{'Id':1, 'FirstName':'John', 'LastName':'Smith'}, {'Id':2, 'FirstName':'Jane', 'LastName':'Doe'}]";
dynamic dJson1= JsonConvert.DeserializeObject(Json1);
Console.WriteLine(dJson1.GetType());
Console.WriteLine(dJson1.Type);
string Json2 = #"{'Id':1, 'FirstName':'John', 'LastName':'Smith'}";
dynamic dJson2 = JsonConvert.DeserializeObject(Json2);
Console.WriteLine(dJson2.GetType());
Console.WriteLine(dJson2.Type);
The program dies on the Console.WriteLine(dJson2.Type) statement. The output of the program is...
Newtonsoft.Json.Linq.JArray
Array
Newtonsoft.Json.Linq.JObject
(should say Object here, I think)
Inspecting the local variables, dJson2 has a "Type" property with value "Object".

This is because JObject behaves similarly as System.Dynamic.ExpandoObject. Try to change your example to:
string Json2 = #"{'Id':1, 'FirstName':'John', 'LastName':'Smith'}";
dynamic dJson2 = JsonConvert.DeserializeObject(Json2);
dJson2.Type = "mynewfield";
Console.WriteLine(dJson2.GetType());
Console.WriteLine(dJson2.Type);
If you want to get property of underlying type you need to cast it (to JToken or JObject), otherwise requested property will be searched in
IDictionary<string, JToken> that JObject implements.
This example may help:
dynamic oobj = new JObject();
oobj.Type = "TEST";
Console.WriteLine(oobj.Type);
Console.WriteLine(((JObject)oobj).Type);

Can't get value from JTOken

I have this JToken
var pv = JToken.Parse(keys["parameterValues"].ToString()).ToList()[0];
Which returns this value
{"DE:Actual Savings": 42217.0}
I can't use .Value because the float is represented as an object {42217.0}
How can I get this number? Right now I am using .ToString() and converting it

To convert the value to a defined type you could use one of the defined methods below:
System.Convert.ChangeType(jtoken.ToString(), targetType);
or
JsonConvert.DeserializeObject(jtoken.ToString(), targetType);
Let's take into consideration our sample:
string json = #{"DE:Actual Savings": 42217.0}
You could do something like:
var obj = (JObject)JsonConvert.DeserializeObject(json);
Type type = typeof(float);
var i1 = System.Convert.ChangeType(obj["DE:Actual Savings"].ToString(), type);
Hope this solves your problem.

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;

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.