simple ORM example for a Book class

book_orm.rb

# This example demonstrates how to generate SQL statements
# to fetch and save objects to a database.

# Warning: It does not do the actual database calls. just returns the statements.

class Book
    attr_accessor :id, :title, :author_id, :subject_id

    def initialize(id, title, author_id, subject_id)
        @id = id
        @title = title
        @author_id = author_id
        @subject_id = subject_id
    end
    def to_s
        @title
    end

    def save
        if @id
            update
        else
            create
        end
    end

    def update
        # make sure to use escaped arguments when you implement this yourself.
        # (with placeholders instead of actual values being passed into the string)
        sql = "UPDATE books SET title=#{@title} WHERE id=#{id}"
    end

    def create
        sql = "INSERT INTO books (title) VALUES (#{@title})"
    end

    def all
        sql = "SELECT * FROM books"
    end

    def self.search(terms)
        sql = "SELECT * FROM books WHERE title ILIKE '%#{terms}%'"
        # CONNECTION does not exist, replace it with your own SQL connection object and exec call
        results = CONNECTION.execute(sql)
        books = []
        results.each do |row|
            book = Book.new(row["id"], row["title"], row["author_id"], row["subject_id"])
            books << book
        end
        books
    end
end

results = Book.search("space")
puts results


book = Book.new
book.title = "How to confuse students in a lecture"
puts book.save