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Keep same Datetime format while reading from JSON in C#

I have a JSON content like this
"started_on": "2017-12-01",
"start_time": "2017-12-01T10:00:00+00:00",
"finish_time": "2017-12-01T11:00:00+00:00",
I want to read the start time and end time as a string in same format and i tried the below code for doing the same
JObject _task = JObject.Parse(response_json);
string _description = "\n start_time:" + (string)_task["start_time"];
_description += "\n finish_time:" + (string)_task["finish_time"];
This reads from JSON correctly , but when i check the datetime format i can see this as like "12/01/2017" only.
How can i keep the same format while doing the conversion and i want the text as it is in the JSON parameter

You need to instruct JSON.NET to read them as strings:
var settings = new JsonSerializerSettings
{
DateParseHandling = DateParseHandling.None
};
JObject _task = JsonConvert.DeserializeObject<JObject>(response_json, settings);
If you need to get some of the values as DateTime objects after they have all been read as strings, you can use this:
var dt = _task["property"].Value<DateTime>();
Although at this stage you may just want to create a class to represent your JSON:
public class MyTask
{
public DateTime Property1 {get;set;} // property1 will be read as a DateTime
public string Property2 {get;set;} // property2 will be read as a string
}
MyTask _task = JsonConvert.DeserializeObject<MyTask>(response_json);

How to read JSON data?

Is this json data format?
string json = {"answer":"Line 1","mark": 1},{"answer":"Line 3","mark": 1}
I try below code but it only working with one param. ex: {"answer":"Line 1","mark": 1}. I try split json string but it isn't best way.
JObject jObject = JObject.Parse(json );
string asw = jObject["answer"].ToString();
int mark = (int)jObject["mark"];
txtAnswer.Text = asw + "////" + mark + "\n";

This is a very basic JSON question which any number of tutorials could've answered for you.
Is it valid JSON ? No, and JSONLint could've told you that.
How do you read it in ?
First, wrap your JSON in square brackets so it's valid.
Then, define a class to store the records in:
public class Something
{
public string answer { get; set; }
public string mark { get; set; }
}
And finally, use JSON.Net to convert your string into a list of these records.
string json = "[{\"answer\":\"Line 1\",\"mark\": 1},{\"answer\":\"Line 3\",\"mark\": 1}]";
List<Something> records = JsonConvert.DeserializeObject<List<Something>>(json); // JSON.Net
foreach (Something record in records)
{
System.Diagnostics.Trace.WriteLine(string.Format("Answer: {0}, Mark: {1}", record.answer, record.mark));
}
Easy as that.

Is this json data format?
string json = {"answer":"Line 1","mark": 1},{"answer":"Line 3","mark": 1}
Nope, what you've got there doesn't look like valid C# or JSON. Try putting it inside a JSON array, then inside a proper string:
string json = "[{\"answer\":\"Line 1\",\"mark\": 1},{\"answer\":\"Line 3\",\"mark\": 1}]";
(Hope I've got all the escaping right there.)
That's the C# escaped equivalent of the following JSON:
[{"answer":"Line 1","mark": 1}, {"answer":"Line 3","mark": 1}]
Then read up on JObject.Parse()for more info.

Yes it is json format. But There are multiple objects. You are not looping through it. One way could be
dynamic dynJson = JsonConvert.DeserializeObject(json);
foreach (var item in dynJson)
{
Console.WriteLine("{0} {1}\n", item.answer, item.mark);
}

Is "[]" valid JSON?

I'm having troubles de-serializing this JSON string using JSON.NET (note the quotes):
"[]"
Depending on which JSON validation website you go to, this is valid JSON (jsonlint for example says it is).
The JSON.NET code:
void Main()
{
string json = "\"[]\"";
var x = JsonConvert.DeserializeObject<User[]>(json);
Console.WriteLine(x);
}
// Define other methods and classes here
public class User
{
public string Id { get; set; }
public int Age { get; set; }
}
The exception
Error converting value "[]" to type 'UserQuery+User[]'. Path '', line 1, position 4.
Is there a way of forcing JSON.NET to parse this?

Part 1: Is "[]" valid JSON?
There are several documents and standards on JSON, and hundreds of parsers; and some of them suppose that JSON can only be object {} or an array [], but some allow single values like strings, numbers to be used as JSON.
Read this article, it widely describes this problem.
What is the minimum valid JSON?
This dispute on JSON validity is another question. In your case, it doesn't matter, because...
Part 2: why your code isn't working.
Even if we allow non-objects \ non-arrays to be valid JSON, then your JSON represents a single string equal to "[]". It could be anything else, not brackets, it is not an array notation, but just two symbols "[" and "]".
However, you try to parse this JSON as an array of objects, which will anyway result into error.
In other words, even if it is a valid JSON, then it is a valid JSON string, not JSON array.
var str1 = JSON.parse("\"[]\""),
str2 = JSON.parse("\"could be anything else, not brackets\""),
arr = JSON.parse("[]");
console.log(typeof str1);
console.log(typeof str2);
console.log(typeof arr);
var str1_s = JSON.stringify([]);
console.log("Valid JSON of an empty array: " + str1_s);
var arr_s = JSON.stringify("[]");
console.log("Partly valid JSON of a string '[]': " + arr_s);
Part 3: what should you do
The best idea - stop using invalid JSON as input. Tell whoever gave you this JSON that it is invalid JSON array and you cannot use it. You would be able to deserialize a JSON into your array of User if it was correct just like you use it:
string json = "[]";
var x = JsonConvert.DeserializeObject<User[]>(json);
Console.WriteLine(x);
If this JSON is provided from 3rd party services and you can do nothing about that, then you need to tidy it up and make it valid. Yeah, unfortunately, sometimes it happens.
How? It depends on what is your value when there ARE objects (users).
It may be a JSON-serialized JSON-string (double-serialized) like this, and then you need to deserialize a string, and then deserialize an array.
Or it can just have two odd quotes in the beginning and the end, and you can just remove them.

It is valid JSON, but the deserializer failes because the datatypes do not match.
"[]"
Is a string, so the deserializer wants to serialize it to a string.
[]
Is an empty array. So, in short, this should work:
string json = "[]";
var x = JsonConvert.DeserializeObject<User[]>(json);
Console.WriteLine(x);

Passing date as string - prevent json.net from parsing date

I have a Web API middle layer which consumes an API which exposes a field which carries a timestamp as string (the field is string and it contains a value like "2016-05-31T14:12:45.753Z").
The proxy classes in the middle tier are generated using Visual Studio from Swagger endpoint and under the hood the object is deserialized using Json.NET.
I can see that the field was received as string (that's good):
inputObject {{ "When": "2016-05-31T14:12:45.753Z" }} Newtonsoft.Json.Linq.JToken {Newtonsoft.Json.Linq.JObject}
However, even though the target field is string the value of inputObject["When"] is a parsed as a timestamp.
inputObject["When"] {31/05/2016 14:12:45} Newtonsoft.Json.Linq.JToken {Newtonsoft.Json.Linq.JValue}
Then
JToken whenValue = inputObject["When"];
if (whenValue != null && whenValue.Type != JTokenType.Null)
{
this.When = ((string)whenValue);
}
In the end this.When is a string with value 31/05/2016 14:12:45.
Is there an option to prevent json.net from parsing the date and then casting it to string again?
Please remember that this transformation happens in auto generated code so I'm looking for some way of decorating the field on the server side which would make Swagger mark it somehow and then the generated classes would avoid the deserialize/serialize issue.
Something like:
[JsonProperty("This really is a string, leave it alone")]
public string When { get; private set; }

(Answering my own question)
I needed a solution quickly and this is my temporary solution, for the record.
I format the date as
"When": "2016-05-31 14:12:45"
and not
"When": "2016-05-31T14:12:45.753Z"
This prevents it from being interpreted. The front end (javascript) code knows that timestamps from the API are UTC and it appends 'Z' before transforming the timestamp to local time and formatting for display, e.g:
<td>{{vm.prettyDateTimeFormat(item.StatusDate+'Z')}}</td>
The ctrl code:
vm.prettyDateTimeFormat = function (dateString)
{
var momentDate = moment(dateString, "YYYY-MM-DD HH:mm:ssZZ");
if (typeof(momentDate) === "undefined" || (!momentDate.isValid()))
{
return dateString;
}
//The format needs to be sortable as it ends up in the grid.
var nicePrettyDate = momentDate.format('YYYY-MM-DD HH:mm:ss');
return nicePrettyDate;
}
As far as I don't like this solution it carried us through the demo. This issue is obviously in the back log now to be addressed properly.

[JsonIgnore]
public string When { get; private set; }

JSON string failing in JSON.parse but passes JsonConvert.DeserializeObject

My C# class is
public class Man
{
public string name {get; set;}
}
String to deserialize is like this
var content = "[{name: \"john\"}]"
Now before saving to db, I was doing check that if string can be deserialized to C# object then store it. This check passes
JsonConvert.DeserializeObject<List<Man>>(content)
So I save this string in db but when I do JSON.parse over saved string in javascript, it crashes with error
JSON.parse("[{name: \"john\"}]")
SyntaxError: Unexpected token n
Now I understand that by surrounding quotes around key ("name") this can be solved. This is correct string that works in both JSON.parse and JsonConvert.DeserializeObject
var content = "[{\"name\": \"john\"}]
Problem is I have many such ill formed strings in db already that crash on JSON.parse only. What is the best way to convert such strings so that JSON.parse will work? Something better than string.replace
Please note that actual strings are quite big and complicated compared to example given.

You can use the using Newtonsoft.Json; it will DeserializeObject object even your json data in var content = "[{name: \"john\"}]" format.
value contains data like :{StyleId:"1710","SelectedItemToColorMap":{1391:"583",21531:"7733"}}
var jsondata = JsonConvert.DeserializeObject(value);
after DeserializeObject the jsondata look like
{
"StyleId": "1710",
"SelectedItemToColorMap": {
"1391": "583",
"21531": "7733"
}
}