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?

Petrus · Answer

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

Riku_Kobayashi · 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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