This blog is part of our Rails 6 series. Rails 6.0 was recently released.

Rails 6 raises ArgumentError when :limit and :precision are used with invalid datatypes.

Before Rails 6, it used to return ActiveRecord::ActiveRecordError.

Let’s checkout how it works.

Rails 5.2

Let’s create an orders table and try using :limit with a column named as quantity with data type integer.

>> class CreateOrders < ActiveRecord::Migration[5.2]
>>   def change
>>     create_table :orders do |t|
>>       t.string :item
>>       t.integer :quantity, limit: 10
>>
>>       t.timestamps
>>     end
>>   end
>> end

=> :change

>> CreateOrders.new.change
-- create_table(:orders)

=> Traceback (most recent call last):
        2: from (irb):11
        1: from (irb):3:in 'change'
ActiveRecord::ActiveRecordError (No integer type has byte size 10. Use a numeric with scale 0 instead.)

We can see that use of :limit with integer column raises ActiveRecord::ActiveRecordError in Rails 5.2.

Now let’s try using :precision of 10 with a datetime column.

>> class CreateOrders < ActiveRecord::Migration[5.2]
>>   def change
>>     create_table :orders do |t|
>>       t.string :item
>>       t.integer :quantity
>>       t.datetime :completed_at, precision: 10
>>
>>       t.timestamps
>>     end
>>   end
>> end

=> :change

>> CreateOrders.new.change
-- create_table(:orders)

=> Traceback (most recent call last):
        2: from (irb):12
        1: from (irb):3:in 'change'
ActiveRecord::ActiveRecordError (No timestamp type has precision of 10. The allowed range of precision is from 0 to 6)

We can see that invalid value of :precision with datetime column also raises ActiveRecord::ActiveRecordError in Rails 5.2.

Rails 6.0.0.rc1

Let’s create an orders table and try using :limit with a column named as quantity with data type integer in Rails 6.

>> class CreateOrders < ActiveRecord::Migration[6.0]
>>   def change
>>     create_table :orders do |t|
>>       t.string :item
>>       t.integer :quantity, limit: 10
>>
>>       t.timestamps
>>     end
>>   end
>> end

=> :change

>> CreateOrders.new.change
-- create_table(:orders)

=> Traceback (most recent call last):
        2: from (irb):11
        1: from (irb):3:in 'change'
ArgumentError (No integer type has byte size 10. Use a numeric with scale 0 instead.)

We can see that use of :limit with integer column raises ArgumentError in Rails 6.

Now let’s try using :precision of 10 with a datetime column.

>> class CreateOrders < ActiveRecord::Migration[6.0]
>>   def change
>>     create_table :orders do |t|
>>       t.string :item
>>       t.integer :quantity
>>       t.datetime :completed_at, precision: 10
>>
>>       t.timestamps
>>     end
>>   end
>> end

=> :change

>> CreateOrders.new.change
-- create_table(:orders)

=> Traceback (most recent call last):
        2: from (irb):12
        1: from (irb):3:in 'change'
ArgumentError (No timestamp type has precision of 10. The allowed range of precision is from 0 to 6)

We can see that invalid value of :precision with datetime column also raises ArgumentError in Rails 6.

Here is the relevant pull request.