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The error while executing azure function : Error in ingest function: Cannot access child value on Newtonsoft.Json.Linq.JValue. Could you please help me with it.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(275.2, 33%, 36%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMM%3C/text%3E%3C/svg%3E)
@Resma Pachikaran ,
Could you please provide the complete stack of the error message?
Are you seeing this error message while executing the function locally or after publishing to Azure functions runtime?
2022-01-06T10:37:54.135 [Error] Error in ingest function: Cannot access child value on Newtonsoft.Json.Linq.JValue.2022-01-06T10:37:54.157 [Information] Executed 'IoTHubtoTwins' (Succeeded, Id=9cff88b9-79e4-4e45-893c-97d60fd0c009, Duration=47ms)2022-01-06T10:37:56.130 [Information] Executing 'IoTHubtoTwins' (Reason='EventGrid trigger fired at 2022-01-06T10:37:56.1304871+00:00', Id=4f6e518b-9546-4c74-8511-60ce0ff65992)2022-01-06T10:37:56.131 [Information] ADT service client connection created.2022-01-06T10:37:56.131 [Information] {"properties": {"temperatureAlert": "false"},"systemProperties": {"iothub-connection-device-id": "firstdevice","iothub-connection-auth-method": "{\"scope\":\"device\",\"type\":\"sas\",\"issuer\":\"iothub\",\"acceptingIpFilterRule\":null}","iothub-connection-auth-generation-id": "637725995472017566","iothub-enqueuedtime": "2022-01-06T10:37:53.734Z","iothub-message-source": "Telemetry"},"body": "eyJtZXNzYWdlSWQiOjQ1MSwiZGV2aWNlSWQiOiJSYXNwYmVycnkgUGkgV2ViIENsaWVudCIsInRlbXBlcmF0dXJlIjoyNS4zNzIwNDU5MjIyNzg1NTYsImh1bWlkaXR5Ijo3MS42NzAzNTczNzMwNTQxOX0="}2022-01-06T10:37:54.135 [Error] Error in ingest function: Cannot access child value on Newtonsoft.Json.Linq.JValue.
This error occurs after publishing to runtime
@Resma Pachikaran , Thanks for the information. You have provided the invocation result. Complete stack would look like below
Hi Thank you for your response. But I am not getting any errors while Debugging the code.
While executing the function in IoTHub I get this error.
@Resma Pachikaran , It appears that the issue is arising from the code and not from the function platform. I would suggest you to add more logging to see which line of code is failing and fixing the error accordingly. Here are some similar discussions on this error message: https://stackoverflow.com/questions/43161432/c-sharp-cannot-access-child-value-on-newtonsoft-json-linq-jvalue
https://helperbyte.com/questions/137748/how-to-solve-the-error-cannot-access-child-value-on-newtonsoftjsonlinqjvalue
https://github.com/octokit/octokit.graphql.net/issues/234
Thank you. I would like to add that I exactly followed the documentation.
@Resma Pachikaran , Are you using the same code that is provided in this documentation ?
https://learn.microsoft.com/en-us/azure/digital-twins/how-to-ingest-iot-hub-data?tabs=cli
Yes..the same one
Super late reply here, but I was having the same issue. The thing is the, string in your body section of the json is encoded in a base64 string. You first need to decode it, and then you'll have access to all the data you have passed in. In your example code above, I see that you passed:
{
"messageId": 451,
"deviceID": "Raspberry Pi Web Client",
"temperature": 25.372045922278556,
"humidity": 71.67035737305419
}
So what I do is first deserialize the first incoming message, then access the body field which is the base64 string, and decode and deserialize it, and now you'd have access to your data fields:
try
{
var cred = new DefaultAzureCredential();
var client = new DigitalTwinsClient(new Uri(adtInstanceUrl), cred);
log.LogInformation($"ADT service client connection created");
if (eventGridEvent != null && eventGridEvent.Data != null)
{
log.LogInformation(eventGridEvent.Data.ToString());
var deviceMessage = (JObject)JsonConvert.DeserializeObject(eventGridEvent.Data.ToString());
var decodedBytes = Convert.FromBase64String(deviceMessage["body"].ToString());
var jsonString = Encoding.UTF8.GetString(decodedBytes);
log.LogInformation(jsonString);
var dataMessage = (JObject)JsonConvert.DeserializeObject(jsonString);
// get our device id, temp and humidity from the object
string deviceId = (string)deviceMessage["systemProperties"]["iothub-connection-device-id"];
var messageId= dataMessage["messageId"];
var deviceID= dataMessage["deviceID"];
var temperature= dataMessage["temperature"];
var humidity= dataMessage["humidity"];
var updateTwinData = new JsonPatchDocument();
updateTwinData.AppendReplace("/messageId", messageId.Value<double>());
updateTwinData.AppendReplace("/deviceID", deviceID.Value<double>());
updateTwinData.AppendReplace("/temperature", temperature.Value<double>());
updateTwinData.AppendReplace("/humidity", humidity.Value<double>());
await client.UpdateDigitalTwinAsync(deviceId, updateTwinData);
}
}
Hope this helps.
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I am also having the same problem. Can you please help where the actual issue is?
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(76.8, 51%, 17%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ERI%3C/text%3E%3C/svg%3E)
Facing the same issue. any help please