studentManagement.js

// StudentManagement
const AWS = require('aws-sdk');
const smdb = new AWS.DynamoDB.DocumentClient();

exports.handler = (event, context, callback) => {
    console.log('Event body: ', event.body);

    const rb = event.body;

    var endPoint = rb.Endpoint;
    var resultPromise;

    if (endPoint == "GetStudents") {
        resultPromise = getStudents();
    } else if (endPoint == "GetStudentById") {
        resultPromise = getStudentById(rb.StudentId);
    } else if (endPoint == "PutStudent") {
        resultPromise = putStudent(rb.NewStudent);
    } else if (endPoint == "DelStudent") {
        resultPromise = delStudent(rb.StudentId);
    } else {
        callback(null, errorResponse("500", "endpoint is not available", context.awsRequestId));
        return;
    }

    resultPromise.then((result) => {
        console.log('Result: ', result.statusCode);
        callback(null, result);
    }).catch((err) => {
        console.error(err);
        callback(null, errorResponse(err.statusCode, err.message, context.awsRequestId));
    });

};

function getStudents() {
    const params = {
        TableName: 'Students'
    };

    let studentsPromise = smdb.scan(params).promise();

    return studentsPromise.then((students) => {
        return students;
    });
}

function getStudentById(studentId) {
    const params = {
        TableName: 'Students',
        FilterExpression: 'StudentId = :uid',
        ExpressionAttributeValues: {
            ":uid": studentId
        }
    };

    let studentsPromise = smdb.scan(params).promise();

    return studentsPromise.then((students) => {
        if (students.Count == 0)
            return errorResponse(404, "Student not found!");

        return students.Items[0];
    });
}

function putStudent(newStudent) {
    const params = {
        TableName: 'Students',
        Item: {
            "StudentId": newStudent.StudentId,
            "FirstName": newStudent.FirstName,
            "LastName": newStudent.LastName,
            "Email": newStudent.Email,
            "Active": newStudent.Active
        }
    }

    let studentPromise = smdb.put(params).promise();

    return studentPromise.then(() => success("Student created!"));
}

function delStudent(studentId) {
    const params = {
        TableName: "Students",
        Key: {
            "StudentId": studentId
        }
    }

    let studentPromise = smdb.transactWrite({
        TransactItems: [{
            Delete: params
        }]
    }).promise();

    return studentPromise.then(() => success("Student deleted!"));
}

function success(result) {
    return {
        statusCode: 200,
        body: result,
    };
}

function errorResponse(status, errorMessage, awsRequestId) {
    return {
        statusCode: status,
        body: {
            Error: errorMessage,
            Reference: awsRequestId,
        }
    };
}