[c#] How to convert JSON to XML or XML to JSON?

I started to use Json.NET to convert a string in JSON format to object or viceversa. I am not sure in the Json.NET framework, is it possible to convert a string in JSON to XML format and viceversa?

You can do these conversions also with the .NET Framework:

JSON to XML: by using System.Runtime.Serialization.Json

var xml = XDocument.Load(JsonReaderWriterFactory.CreateJsonReader(
    Encoding.ASCII.GetBytes(jsonString), new XmlDictionaryReaderQuotas()));

XML to JSON: by using System.Web.Script.Serialization

var json = new JavaScriptSerializer().Serialize(GetXmlData(XElement.Parse(xmlString)));

private static Dictionary<string, object> GetXmlData(XElement xml)
{
    var attr = xml.Attributes().ToDictionary(d => d.Name.LocalName, d => (object)d.Value);
    if (xml.HasElements) attr.Add("_value", xml.Elements().Select(e => GetXmlData(e)));
    else if (!xml.IsEmpty) attr.Add("_value", xml.Value);

    return new Dictionary<string, object> { { xml.Name.LocalName, attr } };
}

I searched for a long time to find alternative code to the accepted solution in the hopes of not using an external assembly/project. I came up with the following thanks to the source code of the DynamicJson project:

public XmlDocument JsonToXML(string json)
{
    XmlDocument doc = new XmlDocument();

    using (var reader = JsonReaderWriterFactory.CreateJsonReader(Encoding.UTF8.GetBytes(json), XmlDictionaryReaderQuotas.Max))
    {
        XElement xml = XElement.Load(reader);
        doc.LoadXml(xml.ToString());
    }

    return doc;
}

Note: I wanted an XmlDocument rather than an XElement for xPath purposes. Also, this code obviously only goes from JSON to XML, there are various ways to do the opposite.

Try this function. I just wrote it and haven't had much of a chance to test it, but my preliminary tests are promising.

public static XmlDocument JsonToXml(string json)
{
    XmlNode newNode = null;
    XmlNode appendToNode = null;
    XmlDocument returnXmlDoc = new XmlDocument();
    returnXmlDoc.LoadXml("<Document />");
    XmlNode rootNode = returnXmlDoc.SelectSingleNode("Document");
    appendToNode = rootNode;

    string[] arrElementData;
    string[] arrElements = json.Split('\r');
    foreach (string element in arrElements)
    {
        string processElement = element.Replace("\r", "").Replace("\n", "").Replace("\t", "").Trim();
        if ((processElement.IndexOf("}") > -1 || processElement.IndexOf("]") > -1) && appendToNode != rootNode)
        {
            appendToNode = appendToNode.ParentNode;
        }
        else if (processElement.IndexOf("[") > -1)
        {
            processElement = processElement.Replace(":", "").Replace("[", "").Replace("\"", "").Trim();
            newNode = returnXmlDoc.CreateElement(processElement);
            appendToNode.AppendChild(newNode);
            appendToNode = newNode;
        }
        else if (processElement.IndexOf("{") > -1 && processElement.IndexOf(":") > -1)
        {
            processElement = processElement.Replace(":", "").Replace("{", "").Replace("\"", "").Trim();
            newNode = returnXmlDoc.CreateElement(processElement);
            appendToNode.AppendChild(newNode);
            appendToNode = newNode;
        }
        else
        {
            if (processElement.IndexOf(":") > -1)
            {
                arrElementData = processElement.Replace(": \"", ":").Replace("\",", "").Replace("\"", "").Split(':');
                newNode = returnXmlDoc.CreateElement(arrElementData[0]);
                for (int i = 1; i < arrElementData.Length; i++)
                {
                    newNode.InnerText += arrElementData[i];
                }

                appendToNode.AppendChild(newNode);
            }
        }
    }

    return returnXmlDoc;
}

I did like David Brown said but I got the following exception.

$exception {"There are multiple root elements. Line , position ."} System.Xml.XmlException

One solution would be to modify the XML file with a root element but that is not always necessary and for an XML stream it might not be possible either. My solution below:

var path = Path.GetFullPath(Path.Combine(Environment.CurrentDirectory, @"..\..\App_Data"));
var directoryInfo = new DirectoryInfo(path);
var fileInfos = directoryInfo.GetFiles("*.xml");

foreach (var fileInfo in fileInfos)
{
    XmlDocument doc = new XmlDocument();
    XmlReaderSettings settings = new XmlReaderSettings();
    settings.ConformanceLevel = ConformanceLevel.Fragment;

    using (XmlReader reader = XmlReader.Create(fileInfo.FullName, settings))
    {
        while (reader.Read())
        {
            if (reader.NodeType == XmlNodeType.Element)
            {
                var node = doc.ReadNode(reader);
                string json = JsonConvert.SerializeXmlNode(node);
            }
        }
    }
}

Example XML that generates the error:

<parent>
    <child>
        Text
    </child>
</parent>
<parent>
    <child>
        <grandchild>
            Text
        </grandchild>
        <grandchild>
            Text
        </grandchild>
    </child>
    <child>
        Text
    </child>
</parent>

Thanks for David Brown's answer. In my case of JSON.Net 3.5, the convert methods are under the JsonConvert static class:

XmlNode myXmlNode = JsonConvert.DeserializeXmlNode(myJsonString); // is node not note
// or .DeserilizeXmlNode(myJsonString, "root"); // if myJsonString does not have a root
string jsonString = JsonConvert.SerializeXmlNode(myXmlNode);

Here is the full c# code to convert xml to json

public static class JSon
{
public static string XmlToJSON(string xml)
{
    XmlDocument doc = new XmlDocument();
    doc.LoadXml(xml);

    return XmlToJSON(doc);
}
public static string XmlToJSON(XmlDocument xmlDoc)
{
    StringBuilder sbJSON = new StringBuilder();
    sbJSON.Append("{ ");
    XmlToJSONnode(sbJSON, xmlDoc.DocumentElement, true);
    sbJSON.Append("}");
    return sbJSON.ToString();
}

//  XmlToJSONnode:  Output an XmlElement, possibly as part of a higher array
private static void XmlToJSONnode(StringBuilder sbJSON, XmlElement node, bool showNodeName)
{
    if (showNodeName)
        sbJSON.Append("\"" + SafeJSON(node.Name) + "\": ");
    sbJSON.Append("{");
    // Build a sorted list of key-value pairs
    //  where   key is case-sensitive nodeName
    //          value is an ArrayList of string or XmlElement
    //  so that we know whether the nodeName is an array or not.
    SortedList<string, object> childNodeNames = new SortedList<string, object>();

    //  Add in all node attributes
    if (node.Attributes != null)
        foreach (XmlAttribute attr in node.Attributes)
            StoreChildNode(childNodeNames, attr.Name, attr.InnerText);

    //  Add in all nodes
    foreach (XmlNode cnode in node.ChildNodes)
    {
        if (cnode is XmlText)
            StoreChildNode(childNodeNames, "value", cnode.InnerText);
        else if (cnode is XmlElement)
            StoreChildNode(childNodeNames, cnode.Name, cnode);
    }

    // Now output all stored info
    foreach (string childname in childNodeNames.Keys)
    {
        List<object> alChild = (List<object>)childNodeNames[childname];
        if (alChild.Count == 1)
            OutputNode(childname, alChild[0], sbJSON, true);
        else
        {
            sbJSON.Append(" \"" + SafeJSON(childname) + "\": [ ");
            foreach (object Child in alChild)
                OutputNode(childname, Child, sbJSON, false);
            sbJSON.Remove(sbJSON.Length - 2, 2);
            sbJSON.Append(" ], ");
        }
    }
    sbJSON.Remove(sbJSON.Length - 2, 2);
    sbJSON.Append(" }");
}

//  StoreChildNode: Store data associated with each nodeName
//                  so that we know whether the nodeName is an array or not.
private static void StoreChildNode(SortedList<string, object> childNodeNames, string nodeName, object nodeValue)
{
    // Pre-process contraction of XmlElement-s
    if (nodeValue is XmlElement)
    {
        // Convert  <aa></aa> into "aa":null
        //          <aa>xx</aa> into "aa":"xx"
        XmlNode cnode = (XmlNode)nodeValue;
        if (cnode.Attributes.Count == 0)
        {
            XmlNodeList children = cnode.ChildNodes;
            if (children.Count == 0)
                nodeValue = null;
            else if (children.Count == 1 && (children[0] is XmlText))
                nodeValue = ((XmlText)(children[0])).InnerText;
        }
    }
    // Add nodeValue to ArrayList associated with each nodeName
    // If nodeName doesn't exist then add it
    List<object> ValuesAL;

    if (childNodeNames.ContainsKey(nodeName))
    {
        ValuesAL = (List<object>)childNodeNames[nodeName];
    }
    else
    {
        ValuesAL = new List<object>();
        childNodeNames[nodeName] = ValuesAL;
    }
    ValuesAL.Add(nodeValue);
}

private static void OutputNode(string childname, object alChild, StringBuilder sbJSON, bool showNodeName)
{
    if (alChild == null)
    {
        if (showNodeName)
            sbJSON.Append("\"" + SafeJSON(childname) + "\": ");
        sbJSON.Append("null");
    }
    else if (alChild is string)
    {
        if (showNodeName)
            sbJSON.Append("\"" + SafeJSON(childname) + "\": ");
        string sChild = (string)alChild;
        sChild = sChild.Trim();
        sbJSON.Append("\"" + SafeJSON(sChild) + "\"");
    }
    else
        XmlToJSONnode(sbJSON, (XmlElement)alChild, showNodeName);
    sbJSON.Append(", ");
}

// Make a string safe for JSON
private static string SafeJSON(string sIn)
{
    StringBuilder sbOut = new StringBuilder(sIn.Length);
    foreach (char ch in sIn)
    {
        if (Char.IsControl(ch) || ch == '\'')
        {
            int ich = (int)ch;
            sbOut.Append(@"\u" + ich.ToString("x4"));
            continue;
        }
        else if (ch == '\"' || ch == '\\' || ch == '/')
        {
            sbOut.Append('\\');
        }
        sbOut.Append(ch);
    }
    return sbOut.ToString();
 }
}

To convert a given XML string to JSON, simply call XmlToJSON() function as below.

string xml = "<menu id=\"file\" value=\"File\"> " +
              "<popup>" +
                "<menuitem value=\"New\" onclick=\"CreateNewDoc()\" />" +
                "<menuitem value=\"Open\" onclick=\"OpenDoc()\" />" +
                "<menuitem value=\"Close\" onclick=\"CloseDoc()\" />" +
              "</popup>" +
            "</menu>";

string json = JSON.XmlToJSON(xml);
// json = { "menu": {"id": "file", "popup": { "menuitem": [ {"onclick": "CreateNewDoc()", "value": "New" }, {"onclick": "OpenDoc()", "value": "Open" }, {"onclick": "CloseDoc()", "value": "Close" } ] }, "value": "File" }}

Yes, you can do it (I do) but Be aware of some paradoxes when converting, and handle appropriately. You cannot automatically conform to all interface possibilities, and there is limited built-in support in controlling the conversion- many JSON structures and values cannot automatically be converted both ways. Keep in mind I am using the default settings with Newtonsoft JSON library and MS XML library, so your mileage may vary:

XML -> JSON

1. All data becomes string data (for example you will always get "false" not false or "0" not 0) Obviously JavaScript treats these differently in certain cases.
2. Children elements can become nested-object {} OR nested-array [ {} {} ...] depending if there is only one or more than one XML child-element. You would consume these two differently in JavaScript, etc. Different examples of XML conforming to the same schema can produce actually different JSON structures this way. You can add the attribute json:Array='true' to your element to workaround this in some (but not necessarily all) cases.
3. Your XML must be fairly well-formed, I have noticed it doesn't need to perfectly conform to W3C standard, but 1. you must have a root element and 2. you cannot start element names with numbers are two of the enforced XML standards I have found when using Newtonsoft and MS libraries.
4. In older versions, Blank elements do not convert to JSON. They are ignored. A blank element does not become "element":null

A new update changes how null can be handled (Thanks to Jon Story for pointing it out): https://www.newtonsoft.com/json/help/html/T_Newtonsoft_Json_NullValueHandling.htm

JSON -> XML

1. You need a top level object that will convert to a root XML element or the parser will fail.
2. Your object names cannot start with a number, as they cannot be converted to elements (XML is technically even more strict than this) but I can 'get away' with breaking some of the other element naming rules.

Please feel free to mention any other issues you have noticed, I have developed my own custom routines for preparing and cleaning the strings as I convert back and forth. Your situation may or may not call for prep/cleanup. As StaxMan mentions, your situation may actually require that you convert between objects...this could entail appropriate interfaces and a bunch of case statements/etc to handle the caveats I mention above.

Cinchoo ETL - an open source library available to do the conversion of Xml to JSON easily with few lines of code

Xml -> JSON:

using (var p = new ChoXmlReader("sample.xml"))
{
    using (var w = new ChoJSONWriter("sample.json"))
    {
        w.Write(p);
    }
}

JSON -> Xml:

using (var p = new ChoJsonReader("sample.json"))
{
    using (var w = new ChoXmlWriter("sample.xml"))
    {
        w.Write(p);
    }
}

Checkout CodeProject article for some additional help.

Disclaimer: I'm the author of this library.

I'm not sure there is point in such conversion (yes, many do it, but mostly to force a square peg through round hole) -- there is structural impedance mismatch, and conversion is lossy. So I would recommend against such format-to-format transformations.

But if you do it, first convert from json to object, then from object to xml (and vice versa for reverse direction). Doing direct transformation leads to ugly output, loss of information, or possibly both.

Here is a simple snippet that converts a XmlNode (recursively) into a hashtable, and groups multiple instances of the same child into an array (as an ArrayList). The Hashtable is usually accepted to convert into JSON by most of the JSON libraries.

protected object convert(XmlNode root){
    Hashtable obj = new Hashtable();
    for(int i=0,n=root.ChildNodes.Count;i<n;i++){
        object result = null;
        XmlNode current = root.ChildNodes.Item(i);

        if(current.NodeType != XmlNodeType.Text)
            result = convert(current);
        else{
            int resultInt;
            double resultFloat;
            bool resultBoolean;
            if(Int32.TryParse(current.Value, out resultInt)) return resultInt;
            if(Double.TryParse(current.Value, out resultFloat)) return resultFloat;
            if(Boolean.TryParse(current.Value, out resultBoolean)) return resultBoolean;
            return current.Value;
        }

        if(obj[current.Name] == null)
            obj[current.Name] = result;
        else if(obj[current.Name].GetType().Equals(typeof(ArrayList)))
            ((ArrayList)obj[current.Name]).Add(result);
        else{
            ArrayList collision = new ArrayList();
            collision.Add(obj[current.Name]);
            collision.Add(result);
            obj[current.Name] = collision;
        }
    }

    return obj;
}

I have used the below methods to convert the JSON to XML

List <Item> items;
public void LoadJsonAndReadToXML() {
  using(StreamReader r = new StreamReader(@ "E:\Json\overiddenhotelranks.json")) {
    string json = r.ReadToEnd();
    items = JsonConvert.DeserializeObject <List<Item>> (json);
    ReadToXML();
  }
}

And

public void ReadToXML() {
  try {
    var xEle = new XElement("Items",
      from item in items select new XElement("Item",
        new XElement("mhid", item.mhid),
        new XElement("hotelName", item.hotelName),
        new XElement("destination", item.destination),
        new XElement("destinationID", item.destinationID),
        new XElement("rank", item.rank),
        new XElement("toDisplayOnFod", item.toDisplayOnFod),
        new XElement("comment", item.comment),
        new XElement("Destinationcode", item.Destinationcode),
        new XElement("LoadDate", item.LoadDate)
      ));

    xEle.Save("E:\\employees.xml");
    Console.WriteLine("Converted to XML");
  } catch (Exception ex) {
    Console.WriteLine(ex.Message);
  }
  Console.ReadLine();
}

I have used the class named Item to represent the elements

public class Item {
  public int mhid { get; set; }
  public string hotelName { get; set; }
  public string destination { get; set; }
  public int destinationID { get; set; }
  public int rank { get; set; }
  public int toDisplayOnFod { get; set; }
  public string comment { get; set; }
  public string Destinationcode { get; set; }
  public string LoadDate { get; set; }
}

It works....

For convert JSON string to XML try this:

    public string JsonToXML(string json)
    {
        XDocument xmlDoc = new XDocument(new XDeclaration("1.0", "utf-8", ""));
        XElement root = new XElement("Root");
        root.Name = "Result";

        var dataTable = JsonConvert.DeserializeObject<DataTable>(json);
        root.Add(
                 from row in dataTable.AsEnumerable()
                 select new XElement("Record",
                                     from column in dataTable.Columns.Cast<DataColumn>()
                                     select new XElement(column.ColumnName, row[column])
                                    )
               );


        xmlDoc.Add(root);
        return xmlDoc.ToString();
    }

For convert XML to JSON try this:

    public string XmlToJson(string xml)
    {
       XmlDocument doc = new XmlDocument();
       doc.LoadXml(xml);

       string jsonText = JsonConvert.SerializeXmlNode(doc);
       return jsonText;
     }