The document discusses Active Record attributes in Rails 5. It explains that Active Record's detected attribute types can be overridden with the attribute method. The attribute method can also define a default value and specify if an attribute is an array or range. Attributes do not require a matching database column. Examples demonstrate overriding an attribute type from decimal to integer, setting default values, and defining array attributes.

1. Active Record in Rails 5
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2. Hello !
I am Neha Suwal
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Associate Software Engineer
Jyaasa Technologies

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Instance Public methods:
attribute(name, cast_type, **options)
Defines an attribute with a type on this model. It will
override the type of existing attributes if needed. This
allows control over how values are converted when
assigned to a model.
attribute :price_in_cents, :integer

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name: The name of the methods to define attribute methods for, and the
column which this will persist to.
cast_type: A symbol such as :string or :integer, or a type object to be used for
this attribute.
options:
default - The default value to use when no value is provided. If this option is not
passed, the previous default value (if any) will be used. Otherwise, the default
will be nil.
array (PostgreSQL only)- specifies that the type should be an array (see the
examples below).
range (PostgreSQL only)- specifies that the type should be a range (see the
examples below).

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The type detected by Active Record can be overridden
#generate a model named StoreDetail with a column price_in_cents whose data
type is decimal
class StoreDetail < ApplicationRecord
end
create_table :store_details do |t|
t.decimal :price_in_cents
t.timestamps
end
store_detail = StoreDetail.create(price_in_cents: '10.1')
store_detail.price_in_cents #=> #<BigDecimal:585ab10,'0.101E2',18(18)>

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#in rails 5
class StoreDetail < ApplicationRecord
attribute :price_in_cents, :integer
end
store_detail.price_in_cents #=> 10

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A default can also be provided
create_table :store_details do |t|
t.decimal :price_in_cents
t.string :name, default: "original default"
t.timestamps
end
store_detail = StoreDetail.create(price_in_cents: '10.1')
store_detail.name #=> “original default”

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#in rails 5
class StoreDetail < ApplicationRecord
attribute :name, :string, default: "new default"
end
new_store_detail = StoreDetail.create(price_in_cents: '1000')
new_store_detail.name #=> "new default"

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Attributes do not need to be backed by a database column
class StoreDetail < ApplicationRecord
attribute :price_in_cents, :integer
attribute :name, :string, default: "new default"
attribute :time, :datetime, default: -> { Time.now }
end
StoreDetail.new.time #=> Mon, 02 Jan 2017 04:48:24 UTC +00:00

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class StoreDetail < ApplicationRecord
attribute :price_in_cents, :integer
attribute :name, :string, default: "new default"
attribute :time, :datetime, default: -> { Time.now }
attribute :field, :integer, array: true
end
store_detail = StoreDetail.new(field: ["1", "2", "3"])
store_detail.field #=> [1, 2, 3]

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store_detail.attributes
#=> {"id"=>nil,
"price_in_cents"=>nil,
"name"=>"new default",
"created_at"=>nil,
"updated_at"=>nil,
"time"=>Mon, 02 Jan 2017 04:52:25 UTC +00:00,
"field"=>[1, 2, 3]}

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Summary:
● The type detected by Active Record can be overridden.
● A default can also be provided.
● Attributes do not need to be backed by a database column.

13. References
http://edgeguides.rubyonrails.org/5_0_release_notes.html
http://api.rubyonrails.org/classes/ActiveRecord/Attributes/ClassMethods.ht
ml
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