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String builder in c# json problem with \" [duplicate]

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C# to JSON serialization using JSON.Net
(2 answers)
Closed 2 months ago.
I created an exaple to demonstrate the problem. I am trying by string builder create a json but there is one problem when the Model.Code contains the \".
If the model value contains double quote json is not valid.
public class Model
{
public string Name { get; set; }
public string Code { get; set; }
}
List<Model> list = new List<Model>();
list.Add(new Model()
{
Name = "Test1",
Code = "124565123"
});
list.Add(new Model() {
Name = "Test2",
Code= "123 \"45"
});
list.Add(new Model()
{
Name = "Test3",
Code = "456"
});
var sb = new StringBuilder();
sb.Append($"\"item_name\":\"{list[0].Name}\",");
sb.Append($"\"item_id\":\"{list[0].Code}\",");
sb.Append($"\"item_name\":\"{list[1].Name}\",");
sb.Append($"\"item_id\":\"{list[1].Code}\",");
sb.Append($"\"item_name\":\"{list[2].Name}\",");
sb.Append($"\"item_id\":\"{list[2].Code}\",");
return sb.ToString();

Add reference to Newtonsoft Json.NET library and serialize the list to json
string json = JsonConvert.SerializeObject(list);

since you are using StringBuilder, " will be Considered as " in the String value just like below
"item_name":"Test1","item_id":"124565123","item_name":"Test2","item_id":"123 "45","item_name":"Test3","item_id":"456",
so , if you want to Convert it to Json , then Json will not Consider value with Double Quote In Between.
Moreover, backslash with double quote ' \" ' suppose to Escape Special Character while Converting to json
I am not sure that you want to Keep that special Character in you Json string If yes then In My Opinion you should try by placing double backslash \\" and Double Quote before your Special Character. and json will Accept it
ex.
\\"45

How to use string interpolation and verbatim string together to create a JSON string literal?

I'm trying to create a string literal representing an array of JSON objects so I thought of using string interpolation feature as shown in the code below:
public static void MyMethod(string abc, int pqr)
{
string p = $"[{{\"Key\":\"{abc}\",\"Value\": {pqr} }}]";
}
Now I thought of using verbatim string so that I don't have to escape double quotes using backslashes. So I came to know through this answer that verbatim string and string interpolation can be used together. So I changed my code as below:
public static void MyMethod(string abc, int pqr)
{
string p = $#"[{{"Key":"{abc}","Value": {pqr} }}]";
}
But it fails to compile. Can anyone help me if there is anything wrong in my usage or it will not be possible to escape double quotes in such a case using string verbatim feature of C#?

The best way is to use JSON serializers as they have in-built handling related to escape characters and other things. See here.
However, if we want to go through this path only to create the JSON string manually, then it can be solved as follows by changing the inner double quotes to single quotes :
public static string MyMethod(string abc, int pqr)
{
string p = $#"[{{'Key':'{ abc}','Value': {pqr} }}]";
return p;
}

I agree with everyone else that building it from strings is a bad idea.
I also understand that you don't want to include an extra dependency.
Here's a bit of code I wrote previously to convert a Dictionary to a JSON string. It's pretty basic, only accepts string types, and doesn't escape quote marks in any of the names/values, but that can be done fairly easily.
If you're trying to serialize a large JSON string from basic types, this is the way I'd recommend to do it. It'll help you stay sane.
private static string DictToJson(Dictionary<string, string> Dict)
{
var json = new StringBuilder();
foreach (var Key in Dict.Keys)
{
if (json.Length != 0)
json = json.Append(",\n");
json.AppendFormat("\"{0}\" : \"{1}\"", Key, Dict[Key]);
}
return "{" + json.ToString() + "}";
}

you can create dictionary and serialize it to json using Json.NET does this.
Dictionary<string, string> values = new Dictionary<string, string>();
values.Add("key1", "value1");
values.Add("key2", "value2");
string json = JsonConvert.SerializeObject(values);
// {
// "key1": "value1",
// "key2": "value2"
// }
you can see here more detail : http://www.newtonsoft.com/json/help/html/SerializingCollections.htm

C# preserve escape sequence when reading JSON content using Json.NET

C# preserve escape sequence when reading JSON content using Json.NET
Given the following json text content:
{ "Pattern": "[0-9]*\t[a-z]+" }
Which is reflected in a simple class:
public class Rule
{
public string Pattern { get; set; }
public bool Test(string text)
{
return new Regex(Pattern).IsMatch(text);
}
}
And it's deserialised like this:
var json = System.IO.File.ReadAllText("file.json");
var rule = JsonConvert.DeserializeObject<Rule>(text);
The value of Pattern is supposed to be a regex pattern. The problem is that, once the content is read, the "\t" escape sequence is immediately applied as a escape character which is a tab, resulting in the string value: [0-9]* [a-z]+.
What I understand is that the content is somewhat malformed, because it should look like this: [0-9]*\\t[a-z]+ to be valid within the Json content, escaping the backslash so it could be preserved and result into the actual pattern [0-9]*\t[a-z]+. But the file is user edited and I would just like to be able to loosely interpret the content, assuming that backslashes should be preserved (and escape sequences would not be transformed).
I tried to implement a custom JsonConverter but when looking up the token, the value is already resolved.
FIDDLE

I've tried the below code and it works...maybe i don't understand what is the problem or you can provide a sample that doesn't work with this:
StreamReader s= new StreamReader(#"test.txt");
string json = s.ReadToEnd();
json=json.Replace("\\","\\\\");
JObject obj = JObject.Parse(json);
string pattern = obj["Pattern"].ToString();
bool test = Regex.IsMatch("1 a", pattern);
test.txt contains just this:
{ "Pattern": "[0-9]*\t[a-z]+" }
Edit
As Thomasjaworsky remarks, instead of json=json.Replace("\\","\\\\"); is better to use Regex.Replace(json, #"(?<!\\)[\\](?!\\)", #"\\")
, it will do the same replace, but only if not already escaped. Two backspaces in row are untouched.

How to read JSON into a JObject when the string contains double quotes ?

I have a piece of JSON that I want to get into a string for C# to use. The problem is when I escape all the double quotes it seems no longer valid. For example:
string jsonString = " {[ { \"FieldId\": \"Fields.364\", \"FieldName\": \"LoanNo\", \"Precision\": \"0\" } , { \"FieldId\": \"Fields.4002\", \"FieldName\": \"LastNameB\" } ]}";
JObject jsettings = JObject.Parse(jsonString);
Is there a easier way to get a string of JSON into a C# JObject?

You're not actually escaping any of the double quotes, as far as the JSON is concerned - the string doesn't contain any backslashes. You can confirm that with Console.WriteLine(jsonString);.
The problem is that you've currently got an array directly inside an object - that's not valid JSON.
If you change it so that the array is a property, it's fine:
string jsonString = " { \"foo\":[ { /* rest as before */ } ] }";
That ended up as JSON of:
{
"foo": [
{
"FieldId": "Fields.364",
"FieldName": "LoanNo",
"Precision": "0"
},
{
"FieldId": "Fields.4002",
"FieldName": "LastNameB"
}
]
}
(Just using Console.WriteLine(jsettings); after the code you'd posted.)

c# inserting variable in JSON string by escaping quotes

I have this JSON double quoted string and I want to insert variable idValue
inside
string json = #"
{
""Request"":
{
""ElementList"":
{
""id"": ""idValue""
}
}
}
In regular string this can be done by "+idValue+" ,but how I can do it here when I have
these double quotes? Thanks.

You can do this :
string json = #"
{
""Request"":
{
""ElementList"":
{
""id"": """+ idValue + #"""
}
}
}";
But personally I'd prefer to use a Json library to stringify my stuff.
Edit: Added missing quotation marks in the string.