C#•2y ago

Newtonsoft.Json.JsonReaderException: "Unexpected character encountered while parsing value: <. Path

Hei all, I am coding a REST API HTTP POST REQUEST, but I always get an error as soon as I start Building the Project. Might it be the way how my JSON is written ? or maybe something else ? the code:

static private void RunAsyncPost(string username, string password)
{
            string url = "http://someIP/rest";

            // Create the JSON request body
            var requestBody = new
            {
                info = new
                {
                    name = "C#testfile.js",
                    type = 282,
                    isDir = false,
                    desc = "",
                    @lock = "",
                    ownerName = "Some Service",
                    access = "WDDRWDE-PIDDS",
                    parentId = 234253
                },
                acl = new[]
                {
                new
                {
                    member = "Administrator",
                    id = 0,
                    type = "USER",
                    access = "RWWEDSGEERLP"
                }
            },
                keywording = new
                {
                    maskNameOriginal = "Incoming Invoice",
                    fields = new
                    {
                        VENDOR_NAME = "Test_Vendor1"
                    }
                }
            };

            // Serialize the JSON request body
            string jsonRequestBody = JsonConvert.SerializeObject(requestBody);

            // Create the HTTP client and request message
            using (var httpClient = new HttpClient())
            using (var requestMessage = new HttpRequestMessage(HttpMethod.Post, url))
            {
                // Set the authorization header
                string authHeader = "Basic " + Convert.ToBase64String(System.Text.Encoding.ASCII.GetBytes($"{username}:{password}"));
                requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Authorization", authHeader);

                // Set the content type and request body
                requestMessage.Content = new StringContent(jsonRequestBody, System.Text.Encoding.UTF8, "application/json");

                // Send the HTTP request and get the response
                var response = httpClient.SendAsync(requestMessage).Result;

                // Check the response status code
                if (response.IsSuccessStatusCode)
                {
                    // Deserialize the response body
                    //var responseBody = JsonConvert.DeserializeObject(response.Content.ReadAsStringAsync().Result);
                    var responseBody = JsonConvert.DeserializeObject<string>(response.Content.ReadAsStringAsync().Result);
                // Do something with the response
                ResponseStream = responseBody.ToString(); // output normaly in CMD but here I am using a textbox of windows Forms
                }
                else
                {
                ResponseStream = $"HTTP error {response.StatusCode}"; // output normaly in CMD but here I am using a textbox of windows Forms
                }
            }

static private void RunAsyncPost(string username, string password)
{
            string url = "http://someIP/rest";

            // Create the JSON request body
            var requestBody = new
            {
                info = new
                {
                    name = "C#testfile.js",
                    type = 282,
                    isDir = false,
                    desc = "",
                    @lock = "",
                    ownerName = "Some Service",
                    access = "WDDRWDE-PIDDS",
                    parentId = 234253
                },
                acl = new[]
                {
                new
                {
                    member = "Administrator",
                    id = 0,
                    type = "USER",
                    access = "RWWEDSGEERLP"
                }
            },
                keywording = new
                {
                    maskNameOriginal = "Incoming Invoice",
                    fields = new
                    {
                        VENDOR_NAME = "Test_Vendor1"
                    }
                }
            };

            // Serialize the JSON request body
            string jsonRequestBody = JsonConvert.SerializeObject(requestBody);

            // Create the HTTP client and request message
            using (var httpClient = new HttpClient())
            using (var requestMessage = new HttpRequestMessage(HttpMethod.Post, url))
            {
                // Set the authorization header
                string authHeader = "Basic " + Convert.ToBase64String(System.Text.Encoding.ASCII.GetBytes($"{username}:{password}"));
                requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Authorization", authHeader);

                // Set the content type and request body
                requestMessage.Content = new StringContent(jsonRequestBody, System.Text.Encoding.UTF8, "application/json");

                // Send the HTTP request and get the response
                var response = httpClient.SendAsync(requestMessage).Result;

                // Check the response status code
                if (response.IsSuccessStatusCode)
                {
                    // Deserialize the response body
                    //var responseBody = JsonConvert.DeserializeObject(response.Content.ReadAsStringAsync().Result);
                    var responseBody = JsonConvert.DeserializeObject<string>(response.Content.ReadAsStringAsync().Result);
                // Do something with the response
                ResponseStream = responseBody.ToString(); // output normaly in CMD but here I am using a textbox of windows Forms
                }
                else
                {
                ResponseStream = $"HTTP error {response.StatusCode}"; // output normaly in CMD but here I am using a textbox of windows Forms
                }
            }

Thanks in advance for any help 🙂

14 Replies

mtreit•2y ago

It sounds like the response body is not JSON.

MeistroOP•2y ago

Hei @mtreit do you mean this line ?

 
var responseBody = JsonConvert.DeserializeObject<string>(response.Content.ReadAsStringAsync().Result);

 
var responseBody = JsonConvert.DeserializeObject<string>(response.Content.ReadAsStringAsync().Result);

mtreit•2y ago

Well you didn't say what line the exception happens on, so I am speculating, but yes since it's an error in the reader that seems like a possible candidate.

MeistroOP•2y ago

Oh yes sorry, I debugged it and the error occurs at that line but the problem is, I dont know what to do

MeistroOP•2y ago

MeistroOP•2y ago

maybe its better to see the code this way

pip•2y ago

you're mostly getting some sort of unauthorized error from the API. that code looks mostly fine(obviously there's some improvements but i won't go into them) do a Console.WriteLine on the result before deserializing make sure its valid json

mtreit•2y ago

Yes, you're probably getting HTML back instead of JSON. Print it out and see what it says.

MeistroOP•2y ago

ok thank you very much. but how do I deserialize it then if this way doesnt work ? I will give you a feed back as soon as I an output from Console

pip•2y ago

if you're getting HTML back from the API, then that means you just have to make sure your request is valid. when your request is valid you will get valid json back validity can be determined by = the info you send in your request, your api keys, the URL you're using for the request etc.

MeistroOP•2y ago

Hei hei, me again. Thank you for the response. I have tryed the console output now and it gave me this

 --------------Post---------------------
<!doctype html>
<html>
<head>
    <!-- Important: rapi-doc uses utf8 charecters -->
    <meta charset="utf-8">
    <script src="js/rapidoc-min.js"></script>
    <style>
        pre.multiline {max-height: 66vh;}
    </style>
</head>
<body>
    <rapi-doc spec-url="./v3/api-docs" show-header="true" allow-spec-file-load="false">
        <img slot="logo" src="elologo.png" />
    </rapi-doc>
</body>
</html>

 --------------Post---------------------
<!doctype html>
<html>
<head>
    <!-- Important: rapi-doc uses utf8 charecters -->
    <meta charset="utf-8">
    <script src="js/rapidoc-min.js"></script>
    <style>
        pre.multiline {max-height: 66vh;}
    </style>
</head>
<body>
    <rapi-doc spec-url="./v3/api-docs" show-header="true" allow-spec-file-load="false">
        <img slot="logo" src="elologo.png" />
    </rapi-doc>
</body>
</html>

lol it worked because a file has been created on server

{"guid":"(A7CB8DE0-C067-E222-4D8A-56C544D67D61)","id":11583,"name":"testDatei.js"}

{"guid":"(A7CB8DE0-C067-E222-4D8A-56C544D67D61)","id":11583,"name":"testDatei.js"}

but the deserialize doenst work

pip•2y ago

hehe

pip•2y ago

check out the docs here on how to make models -> https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/how-to?pivots=dotnet-8-0

How to serialize and deserialize JSON using C# - .NET

Learn how to use the System.Text.Json namespace to serialize to and deserialize from JSON in .NET. Includes sample code.

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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Newtonsoft.Json.JsonReaderException: "Unexpected character encountered while parsing value: <. Path