AWS API Gateway POST request is not working for Lambda function

Question

Here is my lambda function:

@Override
    public List<JobData> handleRequest(Map<String,String> searchFilters, Context context) {
        List<JobData> jobs = new ArrayList<>();
        if(searchFilters.get("job_title") != null){
           // populate jobs list using a method.
        }else{
          // populate jobs list using another method.
        }
        return jobs;      
    }

I used the below test event for testing the lambda:

And the lambda function is working as expected for the above mentioned test input.

Then, I created an API gateway with a POST request triggering the above mentioned lambda function:

Then, I used the REST API gateway to send a POST request with the below body content with a header Content-Type : application/json.

request body:

{
  "job_title": "software engineer"
}

But it is navigating to the else block in the lambda code (indicating that API gateway is not properly intercepting the POST request parameters) which is not expected.

I tried permutations and combinations with the API gateway configurations in AWS. But none of them worked. I get a feel that my lambda function might need to be changed to make it work with API gateway. What can I try next?

Mark B · Accepted Answer · 2022-08-05 14:40:27Z

5

By default, the POST request is not sent directly to the Lambda as the event object. The event object will have much more in it than what you have in your test case, and the actual POST data will be down in one of the event object's properties. If you are using Lambda proxy integration in API Gateway, then the event will look like this.

You have two options:

Create a custom mapping template in API Gateway to convert the event sent to Lambda into what you are expecting.
Modify your Lambda code to handle the format that is currently being sent. I suggest using this library.

answered Aug 5, 2022 at 14:40

Mark B

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1 Comment

Rahul Raj Over a year ago

Thank you Mark. I followed the second option, but I still have no luck. Here is a gist to refer the changes. gist.github.com/rahul-raj/432cd866df6db76fa1434b0860993ef5 . Let me know if I missed anything.

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