Overview
How to store values in models that inherit from ActiveRecord, and which validations are responded to when you enter a value.
Prerequisites.
Rails: 5.2
Ruby: 2.6.1
main topic.
Sample User Table Definitions
create_table :users do |t|
t.string :name
t.integer :state
t.timestamps
end
Defining the user model
There's a variation of the empty character check for name.
class User < ApplicationRecord
validates :name, presence: true
enum state: { show: 0, hide: 1 }
end
Take one model and explain it based on it.
> u = User.first
User Load (0.2ms) SELECT "users". * FROM "users" ORDER BY "users"." "id" ASC LIMIT ? id" ASC LIMIT ? [["LIMIT", 1]]]
=> #<User id: 2, name: "Test 1", created_at: "2019-01-29 03:56:08", updated_at: "2019-03-11 02:52:09", state: "hide">
If you simply output state, you will see the string defined by enum instead of the number stored in the DB.
> u.state.
=> "hide"
Assignment Method
You can substitute symbols defined by enum, strings, or numbers actually stored in the DB.
In the case of symbols
u.state = :hide
=> :hide
irb(main):038:0> u.state
=> "hide"
In the case of a string
u.state = "show"
=> "show"
irb(main):046:0> u.state
=> "show"
In the case of numbers
> u.state = 0
=> 0
> u.state.
=> "show"
Assigning an undefined value
If you try to assign a number outside the range defined by enum, you get an error.
> u.state = "show2"
ArgumentError ('show2' is not a valid state)
irb(main):047:0> u.state = "show2"
Traceback (most recent call last):
1: from (irb):47
ArgumentError ('show2' is not a valid state)
> u.state = :show2
ArgumentError ('show2' is not a valid state)
> u.state = 2
ArgumentError ('2' is not a valid state)
Refer to the actual stored value
You can use u.state for debugging or testing to check which value is actually stored.
Use read_attribute_before_type_cast or attribute_name_before_type_cast.
> u.state.
=> "hide"
u.read_attribute_before_type_cast(:state)
=> 1
irb(main):070:0> u.state_before_type_cast
=> 1
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