Using column modifiers from the command line in Rails Migrations - ruby-on-rails

Question

I am reading the Rails Guides on migrations. It states the following and I quote:
Some commonly used type modifiers can be passed directly on the
command line. They are enclosed by curly braces and follow the field type:
It provides an example:
$ bin/rails generate migration AddDetailsToProducts
'price:decimal{5,2}' supplier:references{polymorphic}
The Rails Guide also provides a list of column modifiers (SQL constraints):
limit
Sets the maximum size of the string/text/binary/integer fields.
precision
Defines the precision for the decimal fields, representing the total number of digits in the number.
scale
Defines the scale for the decimal fields, representing the number of digits after the decimal point.
polymorphic
Adds a type column for belongs_to associations.
null
Allows or disallows NULL values in the column.
default
Allows to set a default value on the column.
index
Adds an index for the column.
So now I want to use a couple of these column modifiers from the command line, but it does not generate the expected migration:
rails generate resource Employee first_name:string{limit,40, null,false} last_name:string{limit,40,null,false} birth_date:date sex:boolean salary:integer supervisor_id:integer{index,true} branch_id:integer{null,false,index,true}
The result:
class CreateEmployees < ActiveRecord::Migration[5.1]
def change
create_table :employees do |t|
t.string{limit,40, :first_name
t.string :null,false}
t.stringlimit :last_name
t.string40 :last_name
t.stringnull :last_name
t.stringfalse :last_name
t.date :birth_date
t.boolean :sex
t.integer :salary
t.integerindex :supervisor_id
t.integertrue :supervisor_id
t.integernull :branch_id
t.integerfalse :branch_id
t.integerindex :branch_id
t.integertrue :branch_id
t.timestamps
end
end
end
What am I doing wrong?

Answer 1

The format you are using is not quite correct. Take a look at rails g model --help for an explanation on how to use the modifiers. Here is a modified version of what you are looking for, though it doesn't handle all of the cases you are interested in:
rails generate resource Employee first_name:string{40} last_name:string{40} birth_date:date sex:boolean salary:integer supervisor_id:integer:index branch_id:integer:index
This generates the following:
class CreateEmployees < ActiveRecord::Migration
def change
create_table :employees do |t|
t.string :first_name, limit: 40
t.string :last_name, limit: 40
t.date :birth_date
t.boolean :sex
t.integer :salary
t.integer :supervisor_id
t.integer :branch_id
t.timestamps null: false
end
add_index :employees, :supervisor_id
add_index :employees, :branch_id
end
end
You will have to manually add the null: false to those entries where you want it.
But, if Branch and Supervisor also AR objects, you can do the following:
rails generate resource Employee first_name:string{40} last_name:string{40} birth_date:date sex:boolean salary:integer supervisor:references branch:references
which generates the following:
class CreateEmployees < ActiveRecord::Migration
def change
create_table :employees do |t|
t.string :first_name, limit: 40
t.string :last_name, limit: 40
t.date :birth_date
t.boolean :sex
t.integer :salary
t.references :supervisor, index: true, foreign_key: true
t.references :branch, index: true, foreign_key: true
t.timestamps null: false
end
end
end
which may be more what you are looking for