Week 10

Mongoose

Question #1

Describe the differences between a SQL and NoSQL DB, and when you might use each.

SQL databases are relational while NoSQL databases aren't. SQL databases use tables while NoSQL databases use documents, key-value pairs and graphs (This means it doesn't have to adhere to a schema).

SQL databases are vertically scalable while NoSql is horizontal.

If you have a lot of data its better to use NoSQL, because the query time for SQL is really long

Question #2

What's wrong with this mongoose code and how might we fix it? (Hint: Assuming there is a document with a name of "Bob", why is results not an author model on the second line?)

var results = AuthorModel.find({name: "Bob"});
console.log(results);

//Mongoose operations require callbacks since they're asynchronous

var results= AuthorModel.find({name: "Bob"}, function(results){
  console.log(results);
})

Question #3

Convert the following ActiveRecord sequence to Mongoose:

@andy = Instructor.find_by(name: "Andy")
@andy.wishlist_items.create(description: "Resin Laying Deer Figurine, Gold")

Instructor.findOne({name: "Andy"}).then(function(instructor){
  instructor.whishlist_items.push({description:"Resin Laying Deer Figurine, Gold"});
  andy.save();
})

Question #4

Convert the following create method in Mongoose to ActiveRecord.

  var authors = {
  create: function(req, res){
  var author = new AuthorModel({name: req.body.name})
  author.save(function(err){
    if (!err){
      res.redirect("authors")
    }
  })
  }  
}

@author = Author.create!(name: params[:name])

Express

Question #5

How does module.exports help us with separation of concerns?


A module takes a bunch related functions and saves it into a package of code that can be used in another file. This helps a lot with separations of concerns because you can create long functions in one file, export them with modules, and then require them in another file.

Question #6

Write one Express route for each of the four HTTP methods.

Then, make each route respond with a one-word string containing the RESTful action that would most likely be associated with this route.

var express = require("express");
var app = express();

app.get("/", function(req, res){
  res.send("index");
});

app.post("/", function(req, res){
  res.send("create");
});
app.post("/:id", function(req, res){
  res.send("update");
});

app.delete("/:id", function(req, res){
  res.send('delete');
});

Question #7

Describe the differences between Express and Rails as backend frameworks.

Rails used Active Record to give it CRUD functionality and PostgreSQL for creating relational databases. Express on the other hand uses Mongoose for CRUD functionality and MongoDB (non-relational database).

Question #8

What is the importance of using body-parser in our express application for post requests? Then, please provide an example of an Express App POST request:

// body-parser extracts the necessary data from incoming requests such as forms.
app.post("/person"), function(req, res){
  res.json(req.body);
});

maureenv/week-10