aws api gateway and lamda - how to get event.body - amazon-web-services

Question

I'm new to aws and I have a strange problem of getting the body of event inside my lamda handler function.
exports.handler = async (event) => {
const response = {
statusCode: 200,
body: event.body
};
return response;
};
When I run test I get
Response:
{
"statusCode": 200
}
However when I only return event
exports.handler = async (event) => {
const response = {
statusCode: 200,
body: event <=====
};
return response;
};
I get
Response:
{
"statusCode": 200,
"body": {
"key1": "value1",
"key2": "value2",
"key3": "value3"
}
}
I'm using node 8.10. Does anybody knows what I'm doing wrong here?

Answer 1

The test event in to Lambda console is exactly what you get as the event parameter in your Lambda handler. When you put {"a":1}, you get {"a":1}.
You can simulate a different event types of AWS service (SNS, S3, API Gateway) selecting a template from the combobox.
As you are returning a HTTP response, you want probably to simulate an API Gateway event, it could look like this:
{
"body": "{\"a\":1}",
"pathParameters": {
"id": "XXX"
},
"resource": "/myres",
"path": "/myres",
"httpMethod": "GET",
"isBase64Encoded": true,
"requestContext": {
"authorizer": {
"tenantId": "TEST"
},
"accountId": "123456789012",
"resourceId": "123456",
"stage": "test",
"requestId": "test-request-id",
"requestTime": "09/Apr/2015:12:34:56 +0000",
"requestTimeEpoch": 1428582896000,
"path": "/myres",
"resourcePath": "/myres,
"httpMethod": "GET",
"apiId": "1234567890",
"protocol": "HTTP/1.1"
}
}
Then you will get the body in event.body as JSON string - you can convert it into an object by JSON.parse(event.body).
When returning, you have to serialize the response body with JSON.stringify:
return {
statusCode: 200,
body: JSON.stingify({your:'object'})
};

Answer 2

Change
exports.handler = async (event) => {
const response = {
statusCode: 200,
body: event.body
};
return response;
};
to
exports.handler = async (event) => {
const response = {
statusCode: 200,
body: JSON.stringify(event.body)
};
return response;
};
The body you return in API Gateway must be stringified, otherwise it doesn't know how to deal with the response.