Lambda function URL ERRO when trying to pass data to it in a browser

Question

I have a function accessing DynamoDB data.  It works perfectly when I hardcode what I wish to scan for, even via a function URL executing from a browser.

Now, instead of hardcoding, I need to pass a piece of data to this function.   However first, I tested the Python code via a test event JSON adding this to it: "Username": "Elvis". At the beginning of the handler in Python, I add:
- myUsername = event.get("Username", {})
- print(Username)
This also worked perfectly.  In Lambda function executes with this test data.

Now, when I delete the test event with the JSON data, and then add to the Lambda URL @ the end of the line:?Username=Elvis, the browser message is: Internal Server Error.

If I retrace my steps by adding back the JSON data of: "Username": "Elvis", and then run the URL as AWS gave it to me when I created the function URL, the return code again is exactly as I expected it.

Also, At the moment to test this, the Auth type is None.  I will add the Auth type when I have the basic features working.

I'm stumped.

Any help?

Answer

Thank you.  Best answer I could not find anywhere online.  You're the best!

Answer

Hello.

If you look at the Lambda log, the element "queryStringParameters" contains parameters.  
Therefore, you can check the "Username" by getting the parameters with "event.get('queryStringParameters')" as shown below.  
https://docs.aws.amazon.com/lambda/latest/dg/urls-invocation.html  
```
import json

def lambda_handler(event, context):
    
    param = event.get('queryStringParameters')
    print(param['Username'])
```

If you include the request body, it will be included in an element called "body", so you can retrieve it as follows.

```
import json

def lambda_handler(event, context):
    
    print(event)
    param = event.get('queryStringParameters')
    print(param['Username'])
    body = event.get('body')
    print(json.loads(body)['Username'])
```
A sample request that includes a request body looks like this:  
```
curl 'https://test.lambda-url.ap-northeast-1.on.aws/?Username=Elvis' -H 'content-type: application/json' -d '{ "Username": "test" }'
```

Lambda function URL ERRO when trying to pass data to it in a browser

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