Response undefined - aws-api-gateway-client - node.js

Question

I have created an AWS API Gateway to invoke a Lambda function to generate random numbers:
Lambda Function :
exports.handler = (event, context, callback) => {
let min = parseInt(event.min);
let max = parseInt(event.max);
let generatedNumber = Math.floor(Math.random() * max) + min;
context.done(null, {generatedNumber: generatedNumber});
};
Body mapping Template in API gateway for get method:
{
"min" : $input.params('min'),
"max" : $input.params('max')
}
When I access API endpoint like below:
https://abcdefgh.execute-api.ap-south-1.amazonaws.com/DEV/number?min=10&max=20
I get the proper response :
{"generatedNumber":28}
But when I try to access the API in node.js using aws-api-gateway-client I am receiving the below response :
_currentUrl: 'https://abcdefgh.execute-api.ap-south-1.amazonaws.com/DEV/number' },
response: undefined
The current url should be set to 'https://abcdefgh.execute-api.ap-south-1.amazonaws.com/DEV/number?min=20&max=40' but it is set to 'https://abcdefgh.execute-api.ap-south-1.amazonaws.com/DEV/number'.
Here is my node.js code to access this api:
let AWS = require('aws-sdk');
AWS.config.loadFromPath('./config.json');
//AWS.config.region = 'ap-south-1';
let lambda = new AWS.Lambda();
let apigClientFactory = require('aws-api-gateway-client').default;
let config = {
invokeUrl: 'https://abcdefgh.execute-api.ap-south-1.amazonaws.com/DEV',
accessKey: '<access-key>',
secretKey: '<secret-key>',
region: 'ap-south-1'
};
let apigClient = apigClientFactory.newClient(config);
let apiParams = '{"min": 20,"max": 40}';
let body = {
}
let additionalParams = {
}
apigClient.invokeApi(apiParams, '/number', 'GET', additionalParams, body)
.then(function (result) {
console.log(result);
})
.catch(function (error) {
console.log(error);
});
I tried changing apiParams to :
let apiParams = {"min": 20,"max": 40};
The I receive the below error:
'{"message": "Could not parse request body into json: Unexpected character (\\\',\\\' (code 44)): expected a value\\n at [Source: [B#42feb146; line: 2, column: 14]"}' } }
What is wrong in my code?
Thanks in advance

Answer 1

Try modifying the mapping template:
{
"min" : "$input.params('min')",
"max" : "$input.params('max')"
}
Source: input-variable-reference

Answer 2

I found the problem. I need to pass parameters in additionalParmaeters object like :
let additionalParams = {
queryParams: {
min: 20, max: 40
}
}
But the text
var params = {
//This is where any header, path, or querystring request params go. The key is the parameter named as defined in the API
userId: '1234',
};
is misleading because query parameters were not passed when parameters were added to params object ( maybe it was for me ), but were only passed when passed inside additionalPrams.
Hope it helps.