Adding data to DynamoDB from the browser (CodePen) fails-CodePudding

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.

CodePudding user response：

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"
    };