Adding data to DynamoDB from the browser (CodePen) fails - amazon-web-services

Question

I am new to AWS and got the following error when I tried to input data to the dynamodb invoking the lambda function between the 'API gateway' and the 'DynamoDB'.
Error:
Expected params.Item['Age'].S to be a string........
Screenshot of the Error:
Code:
I tried in the browser (CodePen) (I used the correct Invoke URL from the API gateway):
var xhr = new XMLHttpRequest();
xhr.open('POST', 'The API Invoke URL');
xhr.onreadystatechange = function(event){
console.log(event.target.response);
}
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.send(JSON.stringify({age: 26, height: 71, income: 2400}));
The following lambda function is invoked when running the above code from CodePen:
There I have imported the aws-sdk and dynamodb correctly.
exports.fn = (event, context, callback) => {
const params = {
Item: {
"UserId": {
S: "user_" + Math.random()
},
"Age": {
N: event.age
},
"Height": {
N: event.height
},
"Income": {
N: event.income
}
},
TableName: "compare-yourself"
};
dynamodb.putItem(params, function(err, data) {
if (err) {
console.log(err);
callback(err);
} else {
console.log(data);
callback(null, data);
}
});
};
In the above lambda function you can observe that I have formatted the inputs as numbers but in the API gateway, in the POST integration request I have converted the inputs to strings. so the data that is passed via the lambda function is already a string. No need to format by the Lambda function, again.
Body mapper in 'POST Integration-Request':
#set($inputRoot = $input.path('$'))
{
"age" : "$inputRoot.age",
"height": "$inputRoot.height",
"income": "$inputRoot.income"
}
I need to know the reason for the above error and am happy to provide any additional information required.
Thank you in advance.

Answer 1

Change the params to indicate that the value of the age field is "String" and not "Numeric":
const params = {
Item: {
"UserId": {
S: "user_" + Math.random()
},
"Age": {
"S": event.age # This was previously set to "N" which causes the issue
},
"Height": {
N: event.height
},
"Income": {
N: event.income
}
},
TableName: "compare-yourself"
};