How to Retrieve a Specific Header from Apache Kafka Connect Responses using ExtractField Transform

Learn how to use Kafka Connect's `ExtractField` transform to retrieve specific headers, like "ID", from response bodies effortlessly.
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How to Retrieve a Specific Header from Apache Kafka Connect Responses Using ExtractField Transform

Apache Kafka Connect is a powerful tool that makes it easier to integrate databases with Kafka. However, sometimes users face challenges when they need to extract specific fields from responses. One common inquiry is how to get a specific header from a Kafka Connector's response body—for example, extracting the "ID" field from a JSON response. If you have encountered similar challenges, this guide offers a clear solution for extracting specific headers efficiently.

The Problem: Extracting the "ID" Header

When dealing with Kafka connectors, you may receive a response body like the following:

[[See Video to Reveal this Text or Code Snippet]]

Your goal here is simple: you want to isolate the "Id" field (in this case, 20030726) and eliminate the rest of the response body. Fortunately, Kafka Connect provides transforms to help us achieve this.

The Solution: Using the ExtractField Transform

To solve the issue of extracting a specific field from the Kafka Connector's response, you can utilize the ExtractField transform. Below is a step-by-step guide on how to implement this:

Step 1: Configure the Connector

When you set up your connector, you need to include the ExtractField transform in your configuration. Here's an example of how to do this:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Specify the Field to Extract

In the above configuration, extractId is the transform we are using to specifically extract the "Id" field from the payload. You can customize it to look something like this:

[[See Video to Reveal this Text or Code Snippet]]

This tells the connector that you want to extract only the field named "Id" from the response.

Step 3: Reconstruct the Payload (if necessary)

If you desire to have the extracted value along with the original payload structure, you can employ the HoistField transform, which will allow you to add the key back to the value after extraction.

To use it, your configuration can include:

[[See Video to Reveal this Text or Code Snippet]]

This way, you can maintain the context by restoring certain fields after extraction.

Conclusion

By utilizing the ExtractField and HoistField transforms, you can seamlessly retrieve specific headers like "ID" from a Kafka Connector response, helping you manage data streams with greater precision. Whether you're working with payloads in development or production, these tools can significantly streamline your Kafka integration process.

Feel free to share your experiences with Kafka Connect or any other questions you have in the comments below. Happy coding!