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Why can't I do something like this:
class CreateModels < ActiveRecord::Migration
def self.up
create_table :fruit do |t|
t.array :apples
end
end
end
Is there some other way to make an array ("apples) be an attribute of an instance of the Fruit class?
824
This can be done in a few ways in Ruby. The first is the plus operator. This will append one array to the end of another, creating a third array with the elements of both. Alternatively, use the concat method (the + operator and concat method are functionally equivalent).
Arrays can contain any combination of Ruby data types -- booleans, integers, strings, or even other collections in the form of nested arrays and hashes. A nested, or multidimensional array, is an array whose individual elements are also arrays.
Ruby | Array append() function Array#append() is an Array class method which add elements at the end of the array. Parameter: – Arrays for adding elements. Return: Array after adding the elements at the end.
In Rails 4 and using PostgreSQL you can actually use an array type in the DB:
Migration:
class CreateSomething < ActiveRecord::Migration
def change
create_table :something do |t|
t.string :some_array, array: true, default: []
t.timestamps
end
end
end
Check out the Rails guide on associations (pay particular attention to has_many).
You can use any column type supported by your database (use t.column instead of t.type), although if portability across DBs is a concern, I believe it's recommended to stick to the types explicitly supported by activerecord.
It seems kind of funny for fruit to have_many apples, but maybe that is just an example? (I would expect apples to be a subclass of fruit).
39
You may use serialize. But if an Apple is going to be an AR object, use associations.
2
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