Hi Everyone, I am currently working as a newcomer in the realm of Azure Digital Twins. I am reaching out to seek your expertise on a particular issue I've encountered. In my current project, I am utilizing TwinCAT3 to establish connectivity with Azure IoT Hub, employing MQTT and JSON functionalities. I am pleased to say that I have successfully managed to transmit data into the Azure IoT Hub. However, I have encountered a challenge in the subsequent step of my process. I have developed a function app with the intention of facilitating the transfer of data from the IoT Hub to Azure Digital Twins. Regrettably, I have encountered an error message stating: 'Error in ingest function: Cannot access child value on Newtonsoft.Json.Linq.JValue.' as shown in the image. Kindly help me with this. I have already contacted Azure regarding this but they say that it needs to be in the form of JSON for this message to go and I also checked from the twincat side that it is JSON. Not sure where I am going wrong. I am using the C# function app sdk for this. Thanks.

Hello @Jayashri Goddanti , welcome to this moderated Azure community forum. The body you get in the Azure Function is a BASE64 version of that JSON string seen in the IoT Explorer preview. Please decode the body BASE64 string to JSON using the programming language (like C# ) you use (every language has libraries for BASE64). You can check this decoding with websites like this . If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.

Azure Function App Erro - Microsoft Q&A

Accepted answer

Sander van de Velde | MVP 32,736 Reputation points MVP

2024-04-29T15:16:31.81+00:00

Hello @Jayashri Goddanti ,

welcome to this moderated Azure community forum.

The body you get in the Azure Function is a BASE64 version of that JSON string seen in the IoT Explorer preview.

Please decode the body BASE64 string to JSON using the programming language (like C#) you use (every language has libraries for BASE64).

You can check this decoding with websites like this.

If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.
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1 person found this answer helpful.
Jayashri Goddanti 45 Reputation points

2024-04-29T15:35:48.6033333+00:00

Hi @Sander van de Velde | MVP

I appreciate your response. I've come across a small solution in the community and integrated a few lines of code into my function app as shown below. However, I'm encountering a peculiar error in my function app, though the message is displayed in the information section. Since I'm relatively new to this, could you kindly advise me on where I should incorporate my decoding part and how? Your guidance would be greatly appreciated. Thank you.

Sander van de Velde | MVP 32,736 Reputation points MVP

2024-04-29T17:13:16.48+00:00

Hello @Jayashri Goddanti ,

because JObject related code is hard to debug, I use deserialization to classes when working with JSON.

Check this blog post with some examples.

Yes, you need to create a few template classes but then it's all typed.

As an alternative check the deserialization to a Dynamic as seen in this blog post.

You are close. Just put some time in honest debugging.

Jayashri Goddanti 45 Reputation points

2024-05-07T09:48:11.8233333+00:00

Hello,

I have tried various ways within the Azure Function App C# SDK to decode base64, and I've even attempted debugging without success. Your assistance would be greatly appreciated. Thank you.

Sander van de Velde | MVP 32,736 Reputation points MVP

2024-05-07T11:25:21.03+00:00

Hello @Jayashri Goddanti ,

The issue seems not related to the base64, I see the correct body values.

The error seems related to the way you ready valies from the JSON.

Have you checked the blog posts?

Please test this code line by line.

Or create a unittest and debug the conversion outside an Azure Function.

Jayashri Goddanti 45 Reputation points

2024-05-07T11:29:28.44+00:00

Hi @Sander van de Velde | MVP I will again try this. Thank you.

Jayashri Goddanti 45 Reputation points

2024-05-07T14:25:40.05+00:00

Hello @Sander van de Velde | MVP I got the connection running now. As you said I had to decode the base 64 string to make it work. Thanks very much for your time.
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