rails documentation

ails g controller Say hello goodbye   //camel case controller

@time = Time.now

<%=

  link_to “anchor text”, [nama-controller]_[nama-view]_path

%>

orm -> object relationship mapping

tabel = orders ,  class = order

rows di tabel = object dr class

ages = []

for person in @people

ages << person.age

end

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rails g scaffold Product title:string description:text image_url:string price:decimal

t.decimal :price, precision: 8 , scale: 2

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###cara gunain seed

db/seeds.rb

Product.delete_all

Product.create!(title: 'programing ruby', description:%{<p>ruby programing<p>}, image_url: ruby.jpg, price: 2.00)

“(Note that this code uses ​%{…}​. This is an alternative syntax for double-quoted string literals, convenient for use with long strings. Note also that because it uses Rails’ ​create!​ method, it will raise an exception if records cannot be inserted because of validation errors.)”

Excerpt From: Sam Ruby, Dave Thomas, David Heinemeier Hansson. “Agile Web Development with Rails 4 (for Lorinda Hartzler).” iBooks. 

rake db:seed

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### cara gunain git

git init

git add .

git commit -m “Depot Scaffold”

git checkout .         -> ngembaliin ke state terakhir

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###validation

app/models/product.rb

validates :title, :description, :image_url, presence: true

validates :price, numericality: {greater_than_or_equal_to: 0.01}

validates :title, uniqueness: true

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#cara gunain fixtures

fixtures :products

one:

  title: MyString

  description: MyText

  image_url: MyString

  price: 9.99

two:

  title: MyString

  description: MyText

  image_url: MyString

  price: 9.99

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## adding path and store

root 'store#index', as: ‘store'

as:’store’   —>>   store_path  

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## cara ngaktifin caching di development!

rails40/depot_e/config/environments/development.rb

​ 

config.action_controller.perform_caching = true”

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model and references

http://guides.rubyonrails.org/association_basics.html

migration

http://guides.rubyonrails.org/active_record_migrations.html

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#bikin references

rails g scaffold LineItem product:references cart:belongs_to

-pada level model tdk ada perbedaan antara references sama belongs_to

lineitem belongs_to :product

lineitem belongs_to :cart

“The database now has a place to store the references between line items, carts, and products.”

“here’s an easy way to remember where to put ​belongs_to​ declarations: if a table has foreign keys, the corresponding model should have a ​belongs_to​ for each.”

>> di models/cart.rb

has_many :line_items, dependent: :destroy

#setiap record di cart dependent terhadap linitem shg apabila dihapus ikt terhapus.

#cart mempunyai berpotensial untuk memiliki banyak lineitems

>> di models/product.rb

has_many :line_items

before_destroy :ensure_not_referenced_by_any_line_item

private

def ensure_not_referenced_by_any_line_item

if line_items.empty?

return true

else

errors.add(:base, 'Line Items present')

return false

end

end

#ngasih hubungan antara product & line_items

#memastikan ketika ada item di delete di line items, product ga ikt kedelete.

“Here we declare that a product has many line items and define a ​hook​ method named ​ensure_not_referenced_by_any_line_item​ . A hook method is a method that Rails calls automatically at a given point in an object’s life. In this case, the method will be called before Rails attempts to destroy a row in the database. If the hook method returns false, the row will not be destroyed.

Note that we have direct access to the ​errors​ object. This is the same place that the ​validates​ stores error messages. Errors can be associated with individual attributes, but in this case we associate the error with the base object.”

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rails generate migration add_quantity_to_line_items quantity:integer