Backend

Question 1

Web Framework

Answer 1

A software framework designed to support web application development

Question 2

Express

Answer 2

A minimalist web framework for Node.js. Express abstracts away many difficulties working directly in Node.

Question 3

Node.js

Answer 3

Node.js brings event-driven programming to web servers, enabling development of fast web servers in JavaScript. Developers can create scalable servers without using threading, by using a simplified model of event-driven programming that uses callbacks to signal the completion of a task.

Question 4

Middleware

Answer 4

A function that an express server runs between receiving a request and responding to that request:

const middleware = (req, res, next) => {
  // Middleware function body
};

Question 5

(req, res, next)

Answer 5

The req parameter stands for request. Information and methods related to the incoming request will be stored in this object.

The res parameter stands for response. This object has information and methods related to sending back a response from the server.

The next parameter, when called, will tell Express that this middleware function is complete. It will then go on to the next piece of middleware.

Question 6

Route

Answer 6

Also called a path, the part of the URL that comes after the domain name

Question 7

Query String

Answer 7

Text that comes at the end of a URL and provides additional information to a given route

Question 8

Query Parameter

Answer 8

A key-value pair in a query string, used to filter the resources requested from the server. The key and the value are strings separated by an equals sign =. In the below example, the query parameter key is q and the value is javascript.

https://www.google.com/search?q=javascript

Question 9

Route Parameter

Answer 9

A part of the URL that changes depending on the data to be displayed on the website, used to access parts of a URL by storing the value in a variable.

Question 10

RESTful APIs

Answer 10

A web API that adheres to the constraints of REST (Representational State Transfer - a set of constraints for building web APIs).

With REST, if you have a URL, then you have a resource. Resource refers to the data returned by a request; that data can be a text file, HTML page, image, video, JSON, or something else. Every URL provides access to a resource on your server.

A RESTful API server provides access to resources. A client, like the browser or another server, can then access and change the resources.

Question 11

HTTP Request Method

Answer 11

Also called an HTTP verb, a method that indicates the desired action (such as deleting a resource) to be taken on a given resource such as GET, POST, PUT, PATCH, and DELETE.

Question 12

API Endpoint

Answer 12

A location where a client can send a request to retrieve a resource that exists on the server

Question 13

HTTP response status code

Answer 13

A code sent along with every HTTP response from the server, indicating the server’s response to the client

Question 14

RESTful Design Principles

Answer 14

URLs should include nouns, not verbs.
Use plural nouns only for consistency (no singular nouns).
Use HTTP methods (HTTP/1.1) to operate on these resources:
Use HTTP response status codes to represent the outcome of operations on resources.
Should

Question 15

CRUD

Answer 15

//(Route name, method, description)

(Create, POST, Create a new post, assign an id, and return at least the id)
(Read, GET, return post/profile with specified id, or return 404 if it doesn’t exist)
(Update, PUT, update an existing post with the data in the request body)
(Delete, DELETE, Delete post with specified id, or return 404 if it doesn’t exist)
(List, GET, Return a list of profiles/posts)

Question 16

HTTP Status Codes

Answer 16

100 -199: Indicates an informational response; unlikely you will need to return a response in this range
200-299: Indicates success; request was received, understood, and processed.
300-399: Indicates redirection; a resource at a different URL has been subbed for the requested resource
400-499: Indicates a client error; there is a problem with the way the client submitted the request
500-599: Indicates a server error; the request was accepted, but an error on the server prevented request’s fulfillment

Question 17

URL

Answer 17

Uniform Resource Locator

Question 18

Controller File

Answer 18

A file that defines and exports the route handler functions and is responsible for managing the state of a single resource in an API

Question 19

Express router

Answer 19

A modular middleware and routing system that can be attached to an Express app

Question 20

Group-by-resource structure

Answer 20

A file organization structure in which any code that handles requests to a resource is stored in a folder with the same name as the resource, regardless of the URL to that resource

Question 21

Database

Answer 21

A database is defined as an organized collection of data, generally stored and accessed electronically from a computer system.

Companies rely heavily on databases to store the data that powers their applications. Databases store a variety of data, such as usernames, email addresses, and nearly every other type of information that you can imagine.

Databases reside behind a huge percentage of websites. They’re a crucial component of e-commerce systems, telecommunications systems, banking systems, video games, and just about any other software system or electronic device that maintains some amount of persistent information. They’re also reliable, efficient, and scalable, and these properties make them exceptionally useful and convenient.

Question 22

Hosted database

Answer 22

Also called a managed database, a cloud-computing service in which the end user pays a cloud service provider for access to a database

Question 23

Relational database management system

Answer 23

RDBMS, a class of programs that can be used to create, update, and administer a relational database

Question 24

Primary key

Answer 24

A field that uniquely identifies the records in a table

Question 25

Data definition language

Answer 25

DDL, a subset of SQL commands used to define the tables in the database

Question 26

SQL

Answer 26

Structured Query Language (SQL) is the database language used to perform operations on a database. You can also use SQL to create a database. SQL uses certain commands, such as CREATE, DROP, and INSERT, to carry out various tasks.

Question 27

One-to-one relationship

Answer 27

A relationship where a single record in one table is related to a single record in another table, and neither column has duplicate records

Question 28

One-to-many relationship

Answer 28

A relationship where a single record in one table is related to multiple records in another table

Question 29

Many-to-many relationship

Answer 29

A relationship where multiple records in one table are related to multiple records in another table

Question 30

Entity Relationship Diagram

Answer 30

ERD, a diagram that allows database designers to visualize the tables and the relationships between the tables in a database. ERDs are fairly common because they provide an easy way to communicate to others about a database model that’s being built.

Question 31

Knex Read

Answer 31

Service:
function read(postId) {
return knex(“posts”).select(“*”).where({ post_id: postId }).first();
}
———————————————————————————————–
Controller:

async function postExists(req, res, next) {
const { postId } = req.params;

  const post = await service.read(postId);
  if (post) {
    res.locals.post = post;
    return next();
  }
  return next({ status: 404, message: `Post cannot be found.` });
}

function read(req, res) {
  const { post: data } = res.locals;
  res.json({ data });
}

module.exports = {
read: [asyncErrorBoundary(postExists), asyncErrorBoundary(read)],
};
————————————————————————————————————

Question 32

Knex Create

Answer 32

Service:

function create(post) {
  //your solution here 
  return knex("posts")
  .insert(post)
  .returning("*")
  .then((createdRecords) => createdRecords[0]);
}
-----------------------------------------------------------------------------
Controller: 

async function create(req, res) {
  // your solution here
const data = await service.create(req.body.data);
  res.status(201).json({data});
}
module.exports = {
  create: asyncErrorBoundary(create),

};

Question 33

Knex Delete

Answer 33

Service:
function destroy(postId) {
return knex(“posts as p”).where( {“p.post_id”: postId}).del();
}
—————————————————————————————
Controller:
async function postExists(req, res, next) {
const { postId } = req.params;

  const post = await service.read(postId);
  if (post) {
    res.locals.post = post;
    return next();
  }
  return next({ status: 404, message: `Post cannot be found.` });
}

async function destroy(req, res) {
await service.delete(res.locals.post.post_id);
res.sendStatus(204);
}
module.exports = {
delete: [asyncErrorBoundary(postExists), asyncErrorBoundary(destroy)],
};

Question 34

Knex List

Answer 34

Service:
function list() {
  return knex("products").select("*");
}
----------------------------------------------------
Controller:
async function list(req, res, next) {
  const data = await productsService.list();
  res.json({ data });
}

Question 35

Knex Update

Answer 35

Service:

function update(updatedPost) {
  return knex("posts as p")
  .select("*")
  .where({ "p.post_id": updatedPost.post_id})
  .update(updatedPost, "*")
  .then((res) => res[0])
}
------------------------------------------------------------------------
Controller:

async function postExists(req, res, next) {
const { postId } = req.params;

  const post = await service.read(postId);
  if (post) {
    res.locals.post = post;
    return next();
  }
  return next({ status: 404, message: `Post cannot be found.` });
}

async function update(req, res) {
  const updatedPost = {
    ...req.body.data,
    post_id: res.locals.post.post_id,
  }
  const data = await service.update(updatedPost)
  res.json({ data });
}

module.exports = {
update: [asyncErrorBoundary(postExists), asyncErrorBoundary(update)],
}