Use string concatenation.

String message = "this is value  want to pass to the ActualMessage attribute " ;
String input = "{\r\n" + 
               "\"Level\": 0,\r\n" + 
               "\"Name\": \"String\",\r\n" + 
               "\"msgName\": \"String\",\r\n" + 
               "\"ActualMessage\": \"" + message + "\",\r\n" + 
               "\"TimeStamp\": \"/Date(-62135596800000-0000)/\"\r\n" + 
               "}" ;

I always recommend using the serialize method to generate correct JSON:

String payload = JSON.serialize(
  new Map<String, Object> {
    'UserID' => username
  });

This will emit the correct JSON, even if your username were to contain special characters, etc.

[TestFixture]
public class DynamicJson
{
    [Test]
    public void Test()
    {
        dynamic flexible = new ExpandoObject();
        flexible.Int = 3;
        flexible.String = "hi";

        var dictionary = (IDictionary<string, object>)flexible;
        dictionary.Add("Bool", false);

        var serialized = JsonConvert.SerializeObject(dictionary); // {"Int":3,"String":"hi","Bool":false}
    }
}

That's not JSON. It's just Javascript objects, and has nothing at all to do with JSON.

You can use brackets to set the properties dynamically. Example:

var obj = {};
obj['name'] = value;
obj['anotherName'] = anotherValue;

This gives exactly the same as creating the object with an object literal like this:

var obj = { name : value, anotherName : anotherValue };

If you have already added the object to the ips collection, you use one pair of brackets to access the object in the collection, and another pair to access the propery in the object:

ips[ipId] = {};
ips[ipId]['name'] = value;
ips[ipId]['anotherName'] = anotherValue;

Notice similarity with the code above, but that you are just using ips[ipId] instead of obj.

You can also get a reference to the object back from the collection, and use that to access the object while it remains in the collection:

ips[ipId] = {};
var obj = ips[ipId];
obj['name'] = value;
obj['anotherName'] = anotherValue;

You can use string variables to specify the names of the properties:

var name = 'name';
obj[name] = value;
name = 'anotherName';
obj[name] = anotherValue;

It's value of the variable (the string) that identifies the property, so while you use obj[name] for both properties in the code above, it's the string in the variable at the moment that you access it that determines what property will be accessed.

Firstly a little clarification; there's no such thing as a 'JSON object'. There is a JSON-formatted string, and there is an object. They are two separate entities.

To add strings to an object, specify the property of the object and set its value. You don't need push() for this as that is used exclusively for arrays. In your case, it should look like this:

var obj = {};
obj.key1 = "value1";
obj.key2 = "value2";
console.log(obj); // = { "key1": "value1", "key2": "value2" }

To set a key dynamically use bracket notation:

var key = 'foo';
obj[key] = 'bar';
console.log(obj); // = { 'foo': 'bar' }

If you need to then convert the object to a JSON string, call JSON.stringify on that object:

var json = JSON.stringify(obj);

Also note that in your second example you end up with an array of strings, not an array of objects. If you want an array of objects you need to remove the quotes around the values you set, like this:

var array = [];
var c = { "key1": "value1" };
var d = { "key2": "value2" };
array.push(c);
array.push(d);
console.log(array); // [{ "key1": "value1" }, { "key2": "value2" }] 

Note the difference in the position of the quotes in the objects and the result from the console.

@NALB, Welcome to Microsoft Q&A， based on my test, I reproduced the same problem with you. The first error due to the url in the xml can not be identified. The second error means that we could not change the json name programmatically. I suggest that you could get the name first and replace the string in the end. Here is a code example you could refer to.

            var json = File.ReadAllText("B:\\ｔ.ｊｓｏｎ");
            var jsonReturn = JsonConvert.DeserializeObject(json);
            string pagestr = string.Empty;
            string str = "";
            foreach (var item in jsonReturn.pages)
            {
                pagestr += item.Name;
                str = Regex.Replace(item.Name, "://", "_");
                str = Regex.Replace(str, ":", "_");
            }
            json=json.Replace(pagestr,str);
            var data = "{\"Row\": " + json + "}";
            XmlDocument doc = JsonConvert.DeserializeXmlNode(data.ToString(), "root");
            Console.WriteLine( doc.InnerXml);

Tested result:

Hope my advice could help you. Best Regards, Jack

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Have you tried using var instead of dynamic?

// Use "var" in the declaration below.
var requirements = order.Title.Commitments[0].Requirements;
string jsonString = JsonConvert.SerializeObject(requirements);

When you only want to deserialize requirements without doing anything else with it then there is no need to use it dynamically.

Sure, you can add properties dynamically to a dynamic object:

var RequestMessage = "{}";
dynamic d = JsonConvert.DeserializeObject(RequestMessage);
d.Request = JsonConvert.SerializeObject(new { A = 42 });
d.RequestOptions = JsonConvert.SerializeObject(new { B = 22 });

var name = "SomeMore";
d[name]=11;

RequestMessage = JsonConvert.SerializeObject(d);

↓

{"Request":"{\"A\":42}","RequestOptions":"{\"B\":22}","SomeMore":11}

Like this:

function createJSON() {
    jsonObj = [];
    $("input[class=email]").each(function() {

        var id = $(this).attr("title");
        var email = $(this).val();

        item = {}
        item ["title"] = id;
        item ["email"] = email;

        jsonObj.push(item);
    });

    console.log(jsonObj);
}

Explanation

You are looking for an array of objects. So, you create a blank array. Create an object for each input by using 'title' and 'email' as keys. Then you add each of the objects to the array.

If you need a string, then do

jsonString = JSON.stringify(jsonObj);

Sample Output

[{"title":"QA","email":"a@b"},{"title":"PROD","email":"b@c"},{"title":"DEV","email":"c@d"}]