mysql and rspec bug - mysql

Question

In Sequel Pro, created a table using this statement:
CREATE TABLE dogs(
id INT PRIMARY KEY NOT NULL,
name TEXT,
color TEXT
);
*auto increment, under extra in structures, is checked so Sequel Pro generate primary keys automatically*
Using mysql2, I author the method insert, in ruby file classdog.rb, to insert a new dog into Table dogs.
classdog.rb is below in its entirety:
require 'mysql2'
require "debugger"
class Dog
attr_accessor :name, :color, :id,
##db = Mysql2::Client.new(:host => '127.0.0.1', :username => 'root', :database => 'dogs')
def initialize(name, color)
#name = name
#color = color
end
def self.db
##db
end
def db
##db
end
def insert
db.query("INSERT INTO dogs(name, color) VALUE('#{name}', '#{color}')")
end
end
dog = Dog.new("simba", "grey")
puts dog.insert
To check if my code is working, I create this rspec file:
require "./classdog"
describe Dog do
describe "#insert" do
it "should insert a dog into the database" do
dog = Dog.new("simba", "grey")
sql_command = "SELECT * FROM dogs WHERE name = '#{dog.name}'";
row_hash = {"id" => 1, "name" => "simba", "color" => "grey"}
expect(Dog.db.query(sql_command).first).to eq(row_hash)
end
end
end
When I run my spec file in ruby using this command:
rspec spec_classdog.rb
My tests passes.
But there 2 things I don't understand:
The table itself only inserts a new dog when I run my spec file, spec_classdog.rb, using rspec. But when I run my ruby file, classdog.rb, no new dog is inserted.
Why is this happening? I expected that running my ruby file could result in new insertions while rspec is just to check to make sure that my method works. It is because I am not passing the parameters name and color to insert method (meaning something like this: dog.insert("spot", "black")?
When I have the following code in my classdog.rb file:
dog = Dog.new("simba", "grey")
puts dog.inspect
puts dog.name
puts dog.color
puts dog.id
Ruby puts:
Notice that dog.id has no output, as seen very clearly below:
dog = Dog.new("simba", "grey")
puts dog.id
why isn't ruby revealing the the id of dog in dog.id?
Is it because id was set as a primay key when the TABLE dog was created?
Will adding a specific column named dog_id help?
#PeterAlfvin: here is an image showing output of running puts dog.insert

Answer 1

Here's at least some of your problems:
Mysql doesn't auto-create primary key columns for you unless you specify auto_increment on the column
The insert method does not provide an id value, so it will always fail, since id is required to be non-null.
Given the above, any entries in your database were not created by the code you've shown.
Given that you've addressed that issue, then you've got the following:
The id value is only being created by mysql in the database, not in the Ruby Dog object, so it will always be nil in the object unless/until you set it (which you are not currently doing).
It has nothing to do with id being a primary key
Creating a dog_id attribute/column/field would have not effect on this
Ruby is revealing the value of dog.id; it's string representation just happens to be the empty string

Answer 2

The reason why a running spec spec_classdog.rb results in the inserting of a new dog is because my rspec file contains sql statements - therefor running rspec file results in sql statement begin carried out.
My rb file does not contain any rspec statements - classdog.rb simply exists to tell each dog object what I want it to do in Ruby-land. Also remember that in Ruby-land dog objects disappear after it is created & has carried out its call; it does not persist. Hence the need for database - resolves the issue of persistence.
See [this link]: How to create/maintain ID field in Sequel Pro via Ruby and mysql2 for answer to the 2nd part of the question.