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

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.

Related

Jsonconvert serializeobject not escaping single quote

C#, I have an Automobile class and in that class i have a vehicleTrim field.
I use JsonConvert.SerializeObject to serialize that class and it is not escaping the single quote.
This is causing an issue when i try to set the value of an object in the web via window.localStorage.setItem function.
example:
public class Automobile
{
public string vehicleTrim { get; set; }
}
var test = new Automobile()
{
vehicleTrim = "designer's package"
};
var serialized = JsonConvert.SerializeObject(test, Formatting.None);
// serialized output: {"vehicleTrim":"designer's package"}
// expected output : {"vehicleTrim":"designer\'s package"}
so now i want to set this json object to the localstorage of my web by calling this
var jsSetScript = $"window.localStorage.setItem('automobile', '{serialized}');";
await Control.EvaluateJavascriptAsync(jsSetScript);
EvaluateJavascriptAsync returns this error trying to read the json SyntaxError: Unexpected identifier 's'. Expected ')' to end an argument list.
I manaully tried this with the escaped single quote and it was fine. So the question is how can i make serializedobject method escape the single quote?

"\'" is not even a valid JSON string literal. From the JSON spec:
Thus ' does not need to be escaped, but if it is, it must appear as "\u0027". Only the 8 listed characters have a special, abbreviated escaping syntax. (For further details see RFC 8259.)
If "\u0027" meets your needs, then setting JsonSerializerSettings.StringEscapeHandling to StringEscapeHandling.EscapeHtml should do the trick. From the docs:
StringEscapeHandling Enumeration
Specifies how strings are escaped when writing JSON text.
Default 0 Only control characters (e.g. newline) are escaped.
EscapeNonAscii 1 All non-ASCII and control characters (e.g. newline) are escaped.
EscapeHtml 2 HTML (<, >, &, ', ") and control characters (e.g. newline) are escaped.
Thus the following now succeeds:
var settings = new JsonSerializerSettings
{
StringEscapeHandling = StringEscapeHandling.EscapeHtml,
};
var serialized = JsonConvert.SerializeObject(test, Formatting.None, settings);
Console.WriteLine(serialized);
// Outputs {"vehicleTrim":"designer\u0027s package"}
Assert.IsTrue(!serialized.Contains('\''));
// Succeeds
Demo fiddle here.

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'}}"

C# JSONConvert.DeserializeObject JSON with Newlines

I have the following sample JSON in a variable called JSONContent
[
{"comment":"This is \\na comment"},
{"comment":"This is another comment"}
]
I type the JSON as such:
public class Comments
{
[JsonProperty("comment")]
public string comment { get; set; }
}
And Deserialize as such:
var Result = JsonConvert.DeserializeObject<List<Comments>>(JSONContent);
I then loop through the RESULT:
// Loop through the JSON object and populate the rows
foreach (var message in Result)
{
doSomething( message.comment );
}
When I inspect the message.comment it shows as:
This is \\na comment
This is another comment
What happens later is I am saving the comment into a database but the database shows the literal "\n" in the result instead of the hopeful newline. This is of course because c# is just converting the \\ to a literal \ and ignoring the n.
I know I can do a replace on the comment, but it feels like I am missing something that tells JSONConvert.DeserializeObject to do this for me.

how to validate JSON string before converting to XML in C#

I will receive an response in the form of JSON string.
We have an existing tool developed in C# which will take input in XML format.
Hence i am converting the JSON string obtained from server using Newtonsoft.JSON to XML string and passing to the tool.
Problem:
When converting JSON response to XML, I am getting an error
"Failed to process request. Reason: The ' ' character, hexadecimal
value 0x20, cannot be included in a name."
The above error indicates that the JSON Key contains a space [For Example: \"POI Items\":[{\"lat\":{\"value\":\"00\"}] which cannot be converted to XML element.
Is there any approach to identify spaces only JSON key's ["POI Items"] and remove the spaces in it?
Also suggest any alternative solution so that we needn't change the existing solution?
Regards,
Sudhir

You can use Json.Net and replace the names while loading the json..
JsonSerializer ser = new JsonSerializer();
var jObj = ser.Deserialize(new JReader(new StringReader(json))) as JObject;
var newJson = jObj.ToString(Newtonsoft.Json.Formatting.None);
.
public class JReader : Newtonsoft.Json.JsonTextReader
{
public JReader(TextReader r) : base(r)
{
}
public override bool Read()
{
bool b = base.Read();
if (base.CurrentState == State.Property && ((string)base.Value).Contains(' '))
{
base.SetToken(JsonToken.PropertyName,((string)base.Value).Replace(" ", "_"));
}
return b;
}
}
Input : {"POI Items":[{"lat":{"value":"00","ab cd":"de fg"}}]}
Output: {"POI_Items":[{"lat":{"value":"00","ab_cd":"de fg"}}]}

I recommend using some sort of Regex.Replace().
Search the input string for something like:
\"([a-zA-Z0-9]+) ([a-zA-Z0-9]+)\":
and then replace something like (mind the missing space):
\"(1)(2)\":
The 1st pair of parenthesis contain the first word in a variable name, the 2nd pair of parenthesis means the 2nd word. The : guarantees that this operation will be done in variable names only (not in string data). the JSON variable names are inside a pair of \"s.
Maybe it's not 100% correct but you can start searching by this.
For details check MSDN, and some Regex examples
http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex.replace.aspx

Json: how to properly strip the escape characters with json.net

I have json response in the below format.
"[{\\\"JobID\\\":\\\"1\\\",\\\"BillGenerationDate\\\":\\\"4/29/2013 2:53:34 PM\\\",\\\"BillID\\\":\\\"115743\\\",\\\"BillNo\\\":\\\"115743\\\",\\\"CustomerID\\\":\\\"4041705\\\",\\\"PayStatus\\\":\\\"0\\\",\\\"PaymentRequiredStatus\\\":\\\"True\\\",\\\"ProductName\\\":\\\"Epic FBO test\\\",\\\"Description\\\":\\\"Epic Automation 2\\\\r\\\\n\\\",\\\"ProductType\\\":\\\"eBill \\\",\\\"DueType\\\":\\\"-1\\\",\\\"DueDate\\\":\\\"2013-03-15\\\",\\\"Amount\\\":\\\"63.70\\\",\\\"Cost\\\":\\\"\\\"},
{\\\"JobID\\\":\\\"9\\\",\\\"BillGenerationDate\\\":\\\"5/2/2013 10:21:39 AM\\\",\\\"BillID\\\":\\\"115743\\\",\\\"BillNo\\\":\\\"115743\\\",\\\"CustomerID\\\":\\\"4041705\\\",\\\"PayStatus\\\":\\\"0\\\",\\\"PaymentRequiredStatus\\\":\\\"True\\\",\\\"ProductName\\\":\\\"FBO Test Product\\\",\\\"Description\\\":\\\"FBO Product Test\\\",\\\"ProductType\\\":\\\"eBill \\\",\\\"DueType\\\":\\\"-1\\\",\\\"DueDate\\\":\\\"2013-05-01\\\",\\\"Amount\\\":\\\"150.70\\\",\\\"Cost\\\":\\\"\\\"}]
I believe json.net handles the escape characters and I used the below code to deserialize it to a dictionary collection.
var billList = JsonConvert.DeserializeObject<List<Dictionary<string, string>>>(contentCorrected);
But this json parsing throws exception
"Invalid property identifier character: . Path '[0]', line 1, position 2."
Could we solve this by manipulating the json response string?

THE SHORT ANSWER: first you need to deserialize the escaped string, but not to the target CLR type, but deserialize to another string (repeat if necessary); then, it is deserialized to the target type:
// Initial example json string: "\"{\\\"Property1\\\":1988,\\\"Property2\\\":\\\"Some data :D\\\"}\""
// First, deserialize to another string (unescaped string).
string unescapedJsonString = JsonConvert.DeserializeObject<string>(escapedJsonString);
Debug.WriteLine(unescapedJsonString);
// Prints:
// "{\"Property1\":1988,\"Property2\":\"Some data :D\"}"
// Second, deserialize to another string, again (in this case is necessary)
var finalUnescapedJsonString = JsonConvert.DeserializeObject<string>(unescapedJsonString);
Debug.WriteLine(finalUnescapedJsonString);
// This time prints a final, unescaped, json string:
// {"Property1":1988,"Property2":"Some data :D"}
// Finally, perform final deserialization to the target type, using the last unescaped string.
MyClass targetObject = JsonConvert.DeserializeObject<MyClass>(finalUnescapedJsonString);
LONG ANSWER (but interesting)
Using string.Replace(... could generate an invalid string, because it could damage certain special characters that needed the backslash to be deserialized correctly .
This type of escaped strings are usually generated when a string that was already a json string, its serialized again (or even more times). This causes something like "various levels of serialization" (it really is a serialization of a string with reserved characters), and the result is backshash characters (or groups of one, two or more backslash followed: \, \, \\\) scattered all over the string.
So, to remove them correctly is not enough to replace them by empty.
THE RIGHT WAY: A better way to get a unescaped string would be to do a first deserialization to string type (Repeat this several times if necessary), And then do a final deserialization to target CLR type:
// -- SERIALIZATION --
// Initial object
MyClass originObj = new MyClass { Property1 = 1988, Property2 = "Some data :D" };
// "First level" Of serialization.
string jsonString = JsonConvert.SerializeObject(originObj);
Debug.WriteLine(jsonString);
// Prints:
// {"Property1":1988,"Property2":"Some data :D"}
// "Second level" of serialization.
string escapedJsonString = JsonConvert.SerializeObject(jsonString);
Debug.WriteLine(escapedJsonString);
// "{\"Property1\":1988,\"Property2\":\"Some data :D\"}"
// Note the initial and final " character and de backslash characters
// ...
// at this point you could do more serializations ("More levels"), Obtaining as a result more and more backslash followed,
// something like this:
// "\"{\\\"Property1\\\":1988,\\\"Property2\\\":\\\"Some data :D\\\"}\""
// Note that is... very very crazy :D
// ...
// -- DESERIALIZATION --
// First deserialize to another string (unescaped string).
string unescapedJsonString = JsonConvert.DeserializeObject<string>(escapedJsonString);
Debug.WriteLine(unescapedJsonString);
// Prints:
// {"Property1":1988,"Property2":"Some data :D"}
// ...
// at this point you could repeat more deserializations to string, if necessary. For example if you have many backslash \\\
// ...
// Finally, perform final deserialization to the target type, using the last unescaped string.
MyClass targetObject = JsonConvert.DeserializeObject<MyClass>(unescapedJsonString);

Try string contentCorrected = contentCorrected.Replace(#"\", "");before deserialization process.

Remove all the "\" character before you deserialize it. Use replace function.
yourJsonString.Replace("\\\\\", "");
Your Json string is incomplete or doesnot seems to be of type List<Dictionary<string, string>>". Correct the type you want the json to be converted.
I modified your json a little as follows and it worked.
newJson = "{ \"array\":" + yourJsonString + "}"

The problem occurs when valid double quotes are used within the answer. Removing and/or Replacing won't solved this in all cases.
It frustrated me too until I found a simple solution:
var billList = JsonConvert.DeserializeObject<List<Dictionary<string, string>>>(#contentCorrected);

For me the code below works
string contentCorrected = contentCorrected.Replace(**#"\""", ""**);

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