Скачать или смотреть Extracting Key Names in S3 with Python

Learn how to efficiently print S3 key names in Python, breaking them down into key segments for easy handling, using AWS Lambda function. Discover practical solutions and string manipulation techniques tailored for S3 triggers.
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Extracting Key Names in S3 with Python: A Step-by-Step Guide

When working with Amazon S3 and AWS Lambda, particularly when there are triggers involved, it's common to need to extract and manipulate file names from S3 object keys. For example, you may want to print a specific part of the key name, such as the directory structure or just the file name. In this guide, we’ll explore how to achieve this in Python, focusing on a scenario where you have an S3 trigger set up to process new uploads.

Understanding the Challenge

You have set up a Lambda function that is invoked whenever a new object is put into an S3 bucket. The key received in the event indicates the path of the object within the bucket. The key you receive looks something like this:

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

Your goal is to extract:

key1: The path without the "jsonfiles/" prefix - which should be 2021/05/31/

key2: Just the file name at the end - which should be file.json

Let’s take a closer look at how to implement this.

Solution: String Parsing in Python

Once you have the full key path string in your Lambda function, you can manipulate it using string operations to get the desired segments. Below are the steps you can take to achieve this.

Step 1: Setup your Lambda Function

Make sure your Lambda function is correctly set up to receive events from S3. Here's the basic setup we will use for extracting our key names:

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

Step 2: Implement the Key Name Extraction Logic

Add a function called extract_key_names which will handle the string parsing of the S3 object key:

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

Step 3: Testing Your Solution

To see your solution in action, upload a test file to the configured S3 bucket. For example, if you upload mys3bucket/jsonfiles/2021/05/31/file.json, your Lambda function should output:

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

Conclusion

By following these steps, you can easily extract and manipulate parts of S3 keys in your AWS Lambda functions using Python. This approach not only helps to retrieve directory structures and file names efficiently, but also enhances your ability to manage files within S3 in a more structured way. Remember, leveraging string methods and understanding how to handle key strings effectively can greatly streamline your AWS operations.

If you found this guide helpful, consider sharing it with others who are looking to enhance their AWS Lambda and Python skills!