sprint2.md

Sprint 2 - relationships & referenced data

1. You enter a vast building full of books.

1. If you have successfully completed all of sprint 1, you should continue working based on your current code. If not, please checkout the solution branch using git checkout solution-sprint-1 so that you can start working on this second sprint. (You need to have all the changes in your current branch checked in to checkout a new branch.) At this point, you should have a node app set up to serve data about books and even allow users to add books, change them, and delete them. Look through any code in server.js and in the models directory that's new to you.

2. Startup the server and open up your browser. Take a look at the updated front-end.

2. More than just a piece of text!

We have authors listed as just a string inside books, but what happens if we want to store more than just an author's name? Let's create a separate model for authors.

1. Create a new file models/author.js.

2. Authors will get attributes for name, alive, and image. Create a schema for authors with those three attributes.

    
    // models/author.js
    var mongoose = require('mongoose');
    var Schema = mongoose.Schema;

    var AuthorSchema = new Schema({
      name: String,
      // you should fill the rest of this in
    });

1. Next, create an Author model from the schema.

     // models/author.js
     var Author = mongoose.model('Author', AuthorSchema);

2. Now, export your Author model.

// models/author.js
module.exports = Author;

Now if another file inside the models directory used require('./author.js'), it would have access to the Author model exported here!

1. We exported the Author model so it's available elsewhere, but now we need to require it in the other file(s) that will use it. We're grouping all our models in models/index.js, so add a line to that file to bring in the new Author model. Also add the Author model to the models/index.js module exports. If you'd like, you can do both in the same line!

module.exports.Author = require("./author.js");

Now since we require('./models') in server.js, server.js automatically gains access to both the Book database model and the Author database model. In fact, the object brought in with require('./models') will be exactly this:

{ "Book": Book,  "Author": Author }

3. Whose book is it anyway?

Now we have a books model and authors has its own model. We want to relate them! Now we'll update books to store an author by reference instead of just storing the name.

Referencing authors is a good choice here because:

• many books might share the same author, and
• we don't want to have to access every single one of an author's books just to make a change to the author's data.

1. We'll need to update the book schema. Change the author line to store a reference to the author:

  var BookSchema = new Schema({
    title: String,
    author: {
      type: Schema.Types.ObjectId,
      ref: 'Author'
    },
    image: String,
    releaseDate: String
  });

4. Authors, assemble!

1. We have all the tools we need to start making authors. Add the following data to your seed.js file.

  var authors_list = [
    {
      name: "Harper Lee",
      alive: false
    },
    {
      name: "F Scott Fitzgerald",
      alive: false
    },
    {
      name: "Victor Hugo",
      alive: false
    },
    {
      name: "Jules Verne",
      alive: false
    },
    {
      name: "Sheryl Sandberg",
      alive: true
    },
    {
      name: "Tim Ferriss",
      alive: true
    },
    {
      name: "John Steinbeck",
      alive: false
    },
    {
      name: "William Shakespeare",
      alive: false
    }
  ];

1. Now we need to edit our seed.js file to create books and authors being sure to connect the two together. Remove all the other functions and replace with:

  
    db.Author.remove({}, function(err, authors) {
      console.log('removed all authors');
      db.Author.create(authors_list, function(err, authors){
        if (err) {
          console.log(err);
          return;
        }
        console.log('recreated all authors');
        console.log("created", authors.length, "authors");


        db.Book.remove({}, function(err, books){
          console.log('removed all books');
          books_list.forEach(function (bookData) {
            var book = new db.Book({
              title: bookData.title,
              image: bookData.image,
              releaseDate: bookData.releaseDate
            });
            db.Author.findOne({name: bookData.author}, function (err, foundAuthor) {
              console.log('found author ' + foundAuthor.name + ' for book ' + book.title);
              if (err) {
                console.log(err);
                return;
              }
              book.author = foundAuthor;
              book.save(function(err, savedBook){
                if (err) {
                  console.log(err);
                }
                console.log('saved ' + savedBook.title + ' by ' + foundAuthor.name);
              });
            });
          });
        });

      });
    });

1. Run node seed.js in your terminal again to re-add the books and add the new authors.

5. Reroute!

Some of our book-related routes won't work anymore since we changed the structure of our data.

1. Now on to server.js. Try to change over your routes to use the new structure of books and authors. If you get stuck, here's how to change over a few routes:

    // get all books
    app.get('/api/books', function (req, res) {
      // send all books as JSON response
      db.Book.find()
        // populate fills in the author id with all the author data
        .populate('author')
        .exec(function(err, books){
          if (err) { console.log("index error: " + err); }
          res.json(books);
        });
    });

    // create new book
    app.post('/api/books', function (req, res) {
      // create new book with form data (`req.body`)
      var newBook = new db.Book({
        title: req.body.title,
        image: req.body.image,
        releaseDate: req.body.releaseDate,
      });

      // this code will only add an author to a book if the author already exists
      db.Author.findOne({name: req.body.author}, function(err, author){
        newBook.author = author;
        // add newBook to database
        newBook.save(function(err, book){
          if (err) {
            console.log("create error: " + err);
          }
          console.log("created ", book.title);
          res.json(book);
        });
      });

    });

6. But the view from here is bad!

1. When you look at your view, instead of seeing the nicely listed author, you should see the author object.

2. Why is this? Look at the data being returned from the server and fix the template string to show the author name!

  <p>
    <b>${book.title}</b>
    <!-- just this next line is what needs to be changed! -->
    by ${book.author.name}
    <button type="button" name="button" class="deleteBtn btn btn-danger pull-right" data-id=${book._id}>Delete</button>
  </p>

Revise Other CRUD methods to Account for Authors

On your own, use the mongoose methods to replace the other /api/books* routes with mongoose commands, taking into account the new referenced data relationship.

Make sure you look back to the lecture notes for info on the most important methods like:

• find
• findOneAndRemove
• new
• save