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How to parse a complicated nested JSON string in C#?

I have an ugly JSON string that is getting returned from an API that looks like this (this is the result of Console.Write on the string):
{"d":"\"\\\"\\\\\\\"[{\\\\\\\\\\\\\\\"foo\\\\\\\\\\\\\\\":15,\\\\\\\\\\\\\\\"bar\\\\\\\\\\\\\\\":null}]\\\\\\\"\\\"\\n\""}
I am trying to parse this into a C# object in the simplest way possible, so I can access properties like foo and bar. But I am having a difficult time doing this.
I have tried parsing it a number of ways, including:
// code to get the response string
client.Headers.Add(HttpRequestHeader.ContentType, "application/json");
var serializedData = "{data: 'data'}";
var responseString = client.UploadString(url, "POST", serializedData);
// parse the response string
dynamic obj = Newtonsoft.Json.JsonConvert.DeserializeObject(jsonString);
This allows me to access the value of d, which is the actual string I need to parse. I then tried to parse that separately using JArray.Parse(obj["d"]), but I get an error saying that obj["d"] is not an array.
Unfortunately, I have no access to the API itself so can't modify how it's serializing the data it's returning.
Any suggestions?

You can replace all New Line, Backslash, Double quotes to format the JSON
var formattedJson = jsonString.Replace(#"\n", string.Empty)
.Replace(#"\", string.Empty)
.Replace("\"\"", string.Empty);
Console.WriteLine(formattedJson);
OUTPUT
{
"d": [
{
"foo": 15,
"bar": null
}
]
}
Convert to JArray.
var jArray = JArray.Parse(JObject.Parse(formattedJson)["d"].ToString());
Console.WriteLine($"{jArray[0]["foo"]} {jArray[0]["bar"]}");
OUTPUT
15

The problem is that the value of "d" is a string representing a string representing a string ... representing an array. You could call it JSON serialization "inception".
The way to deal with this is to deserialize the value corresponding number of times. If you're sure that the value is never going to be an actual string, you could do it like this, without having to know how many times the value was serialized:
var myObject = JObject.Parse(s);
var d = myObject["d"];
while(d.Type == JTokenType.String)
d = JToken.Parse(d.ToObject<string>());
myObject["d"] = d;
After this procedure myObject represents this data:
{
"d": [
{
"foo": 15,
"bar": null
}
]
}

Replacing escape characters in fine however I would not rely on the console.write command as the definitive output to examine. Here are a couple of other ways: -
Use Postman to make the API call so you can see the raw result. This will (hopefully) show it in an easy to read format that you can then define your class to deserialise to.
Write the raw response to a “.json” file. Open that file in a good editor (such as VS Code or VS itself) to see how the data is actually structured when it is received.
On a side note I would recommend using RestSharp to do the REST calls and Newtonsoft.Json to do the serialising/deserialising.

Json get array object from JSON Object C#

I have this json string passed to my webapi
string jsonstring = "{\"datamodel\": \"[{\"K1\":\"V1\",\"K2\":\"V2\"}]\"}";
I may have more than on pair of (K,V) inside. How do i parse this in C# ?
I thought i could first convert my string to a JObject and get the key for datamodel from that and then use JArray to parse the K,V. But its throwing a jsonreader exception on the first line of code here
JObject my_obj = JsonConvert.DeserializeObject<JObject>(jsonstring.ToString());
and then do this..
JObject data = my_obj["datamodel"].Value<JObject>();

First of all, the JSON string you are posting is not valid. Given your comment, you can clean up the quotes before and after the square brackets using this snippet:
string jsonstring = "{\"datamodel\": \"[{\"K1\":\"V1\",\"K2\":\"V2\"}]\"}";;
string jsonstringCleaned = jsonstring.Replace("\"[", "[").Replace("]\"", "]");
var my_obj = JsonConvert.DeserializeObject<JObject>(jsonstringCleaned);

The code is right, but the exception you are getting is related to the formatting of your JSON string. If you put valid JSON in this code, it should work as expected.

There are \" missing around V1 in your JSON string.
It should look like this:
string jsonstring = "{\"datamodel\": \"[{\"K1\":\"V1\",\"K2\":\"V2\"}]\"}";

First always make sure that you have a valid Json string. A simple way to do that is paste it into a Json to C# converter tool, such as this one: http://json2csharp.com/
It may be simpler and more readable to use single quotes within your Json string if that is an option, as it avoids the need to escape the double quotes:
string jsonstring = "{'datamodel': [{'K1':'V1','K2':'V2'}]}"
Now we deserialize the object and get the JArray. There is no need to call the ToString() on the JSON jsonstring string.
var my_obj = JsonConvert.DeserializeObject<JObject>(jsonstring);
var data = (JArray)my_obj["datamodel"];
A better and more concise way to accomplish the same result could be to just use JObject.Parse. We can accomplish the same result with just one line of code.
var data = (JArray)JObject.Parse(jsonstring)["datamodel"];

Deserialize json string that contains singlequote using c#

I have a json string that contains a string literal as value of one of the object - PostData.
string json = "{\"PostData\": '{\"LastName\": \"O Corner\",\"FirstName\":\"Mark\",\"Address\":\"123 James St\"}'}";
I am trying to deserialize the json using:
var obj = JsonConvert.DeserializeObject<dynamic>(json);
then, I can use my json string value of PostData like:
obj["PostData"].ToString()
But, as soon as I get the data with single quotes in it, like:
string json = "{\"PostData\": '{\"LastName\": \"O' Corner\",\"FirstName\":\"Mark\",\"Address\":\"123 James St\"}'}";
I get exception on deserialization. How can I escape the single quote?
I have checked SO for similar issues but didn't get any thing working. I also tried one of the solution mentioned int his thread:
JsonSerializerSettings settings = new JsonSerializerSettings
{
StringEscapeHandling = StringEscapeHandling.EscapeHtml
};
JsonConvert.SerializeObject(obj, settings);
But, I get Newtonsoft doesnot contain defination for StringEscapeHandling.
Also, tried to escape the singlequote with in the string with \:
'{\"LastName\": \"O\' Corner\",\"FirstName\":\"Mark\",\"Address\":\"123 James St\"}' which didn't work either.

For a start, it might be worth noting that the JSON syntax uses single quotes where you have used double quotes. Here is a guide for proper syntax:
Now unfortunately JSON does not allow the use of single quotes like that, but we can use the unicode \u0027 for an apostrophe and make use of JSON's serializer settings, as you have already done. So your original string:
string json = "{\"PostData\": '{\"LastName\": \"O' Corner\",\"FirstName\":\"Mark\",\"Address\":\"123 James St\"}'}";
becomes:
string json = "{'PostData': {'LastName': 'O\u0027 Corner','FirstName':'Mark','Address':'123 James St'}}"
This is assuming that you are parsing a string literal, otherwise you would need to escape the unicode to give:
string json = "{'PostData': {'LastName': 'O\\u0027 Corner','FirstName':'Mark','Address':'123 James St'}}"

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"
}
}

Retrieve Json from service and pass to ApiController

I want to directly capture JSON from an external API in a service layer, return that to a MVC 4 ApiController, and then output the JSON through that ApiController. I'm basically writing a wrapper around another API service because some other actions have to happen at the same time (authentication, etc). The problem is that the JSON gets converted to a string and is passed around as a string in my C# code. This just adds escape characters to the JSON. Is there anyway I can just pass the JSON object around in my C# code? Details of my implementation are below.
In a service layer, I'm consuming an API that provides JSON via the method below.
return new WebClient().DownloadString(url);
Unfortunately this returns a string. As this API is already returning JSON to me this is problematic because lots of escape characters get added to the string.
The JSON should look something like this
[{"Citation":{"Attachments":[{"AttachedPersonIds":null,..."Type":"Record"}]
But instead it now looks like this
"[{\"Citation\":{\"Attachments\":[{\"AttachedPersonIds\":null,...\"Type\":\"Record\"}]"
After I get this string I return it through a couple of methods to an ApiController (which is setup to return JSON) like this.
public class HintsController : ApiController
{
public string Get(string treeId, string personId)
{
return _hintService.GetHints(treeId, personId);
}
}
I've tried to convert the string to a Literal string and tried serializing the string again. Doing this just adds more escape characters and doesn't solve the problem. I think the problem is with how I'm consuming the initial call because it's casting it from JSON to a string. But I don't know how to avoid this.
Thanks in advance for any ideas.

Because the controller returns a string, the JSON formatter is serializing the entire string to a JSON string and escaping the embedded quote characters.
You can do something like this:
public HttpResponseMessage Get()
{
var resp = new HttpResponseMessage()
{
Content = new StringContent("{json here...}")
};
resp.Content.Headers.ContentType =
new MediaTypeHeaderValue("application/json");
return resp;
}
This assumes that you always want to return JSON.

You can turn it into a dynamic object and pass that around, if you really want to pass the objects.
I can't tell where the literal escape characters are coming from, can you be a little more clear on that. Is the API generating them, or is there some other point in our code? I've seen them in the debug window before, when the string didn't actually contain them, and printing/etc worked normally.
You can use Json.net (standard), the built in serializer, https://github.com/jsonfx/jsonfx and others .
From the jsonfx site:
var reader = new JsonReader(); var writer = new JsonWriter();
string input = #"{ ""foo"": true, ""array"": [ 42, false, ""Hello!"", null ] }";
dynamic output = reader.Read(input);
Console.WriteLine(output.array[0]); // 42
string json = writer.Write(output);
Console.WriteLine(json); // {"foo":true,"array":[42,false,"Hello!",null]}
There are a few other ways ways, see these threads:
Deserialize json object into dynamic object using Json.net
Deserialize JSON into C# dynamic object?