C# Converting string to JSON

Question

I am trying to POST to using C# to a JSON payload which I can achieve but I am having trouble understanding how to replace the sample string with my own string.

From the code below you can see I have a string I want to send to my weblink. The code runs fine when I use "{\"text\":\"Hello, World!\"}" for the StringContent but if I try to replace it with the string of output_message it doesn't work. I am trying to work out how I convert my output_message to a format that JSON can recognize.

    {
        string output_message = "The file " + filename + " has been modified by " + user_modified + " and moved to the " + file_state + " file state. Please review the " + filename + " file and approve or reject.";            
        PostWebHookAsync(output_message);
        Console.ReadLine();
    }
    static async void PostWebHookAsync(string Aoutput_message)
    {
        using (var httpClient = new HttpClient())
        {
            using (var request = new HttpRequestMessage(new HttpMethod("POST"), "www.mywebsitelink"))
            {
                //request.Content = new StringContent("{\"text\":\"Hello, World!\"}", Encoding.UTF8, "application/json");  // - original do not delete
                request.Content = new StringContent(Aoutput_message, Encoding.UTF8, "application/json");
                var response = await httpClient.SendAsync(request);
               Console.WriteLine(response.StatusCode);
               Console.WriteLine(response.Content);
            }
        }
    }

I want to replace "{\"text\":\"Hello, World!\"}" with a string

JSON is stand for JavaScript **Object** Notation, so it has some validation rules. In your case, you can send `$"\{\"text\":\"{output_message}\"\}"` or `$"\{\"value\":\"{output_message}\"\}"`, or even `$"[\"{output_message}\"]"` — vasily.sib, May 13 '19 at 10:48
Possible duplicate of [Convert JSON String To C# Object](https://stackoverflow.com/questions/4611031/convert-json-string-to-c-sharp-object) — , May 13 '19 at 10:49

score 1 · Answer 1 · edited May 13 '19 at 11:21

The best way is to create an object and serialize it.

To use JavaScriptSerializer you have to add a reference to System.Web.Extensions.dll

So for your problem, we create an anonymous object with a property text we pass the value Aoutput_message

static async void PostWebHookAsync(string Aoutput_message)
{
    using (var httpClient = new HttpClient())
    {
        using (var request = new HttpRequestMessage(new HttpMethod("POST"), "www.mywebsitelink"))
        {
            //request.Content = new StringContent("{\"text\":\"Hello, World!\"}", Encoding.UTF8, "application/json");  // - original do not delete

            string jsonValue = new JavaScriptSerializer().Serialize(new
            {
                text = Aoutput_message,
            });

            request.Content = new StringContent(jsonValue, Encoding.UTF8, "application/json");
            var response = await httpClient.SendAsync(request);
            Console.WriteLine(response.StatusCode);
            Console.WriteLine(response.Content);
        }
    }
}

Examples

Palle Due · Accepted Answer · 2019-05-13T12:21:31.907

To the best of my knowledge people are moving away from JavaScriptSerializer and towards Json.NET. It's even recommended in the documentation here

The corresponding Json.NET code would look something like:

static async void PostWebHookAsync(string output_message)
{
    using (var httpClient = new HttpClient())
    {
        using (var request = new HttpRequestMessage(new HttpMethod("POST"), "www.mywebsitelink"))
        {
            string jsonValue = JsonConvert.SerializeObject(new
            {
                text = output_message
            });
            request.Content = new StringContent(jsonValue, Encoding.UTF8, "application/json");
            var response = await httpClient.SendAsync(request);
            Console.WriteLine(response.StatusCode);
            Console.WriteLine(response.Content);
        }
    }
}

To use Json.NET you need to install the Newtonsoft.Json nuget package.

This also work, thanks for your feedback. Whats the benefits of using this over the JavaScriptSerializer().Serialize function? — AWH, May 13 '19 at 14:00
@AWH: JavaScriptSerializer is not supported in .NET Core, so in order to make it "future-proof" you should use Json.NET. When deserializing I find Json.NET easier to work with, for serialization it's same-same. — Palle Due, May 13 '19 at 14:25

C# Converting string to JSON

2 Answers2