Rails MySQL ILIKE query

Question

My syntax is off. I want to create a scope by_name that finds all agencies whose name attribute contains the passed in string (case insensitive).

Here is what I have:

class Agency < ActiveRecord::Base
  scope :by_name, ->(agency_name) { where('name ILIKE ?', "%#{agency_name}%") }
end

In the rails console I type in agencies = Agency.by_name("foo"). Here is the query generated:

SELECT `agencies`.* FROM `agencies`  WHERE (name ILIKE '%foo%')

Here is the error message:

Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ILIKE '%foo%')

Solution 1

I think it should be:

 scope :by_name, lambda { |agency_name| 
   where('name LIKE ?', "%#{agency_name}%") # not ILIKE
 }

It is in PostgreSQL the keyword ILIKE can be used instead of LIKE to make the match case-insensitive according to the active locale. This is not in the SQL standard but is a PostgreSQL extension.

In MySQL you do not have ILIKE. Checkout MySQL docs on string comparison functions.

---

Bonus - you can also use Arel. Take a look:

scope :by_name, lambda { |agency_name| 
  where(Agency.arel_table[:name].matches("%#{agency_name}%"))
}

Solution 2

Why yes, because there's no such thing as ILIKE in MySQL. Only LIKE. You may have seen ILIKE as a case-insensitive version of LIKE in PostgreSQL, but your current RDBMS is different.

Your best bet is using LOWER on both sides to achieve mostly equivalent effect:

.where('LOWER(name) LIKE LOWER(?)', "%#{agency_name}%")

Credit to @mu is too short for his answer.

Comments

[Gary Benade]

This is not an ideal solution because this will not allow the query optimiser to use an index if one exists on the name column, a better solution would be to set the collation of your table to utf8_general_ci - the ci means case insensitive, doing this will make all text matches case insensitive

[Vael Victus]

@GaryBenade What if I want to allow the user to search with a case-sensitivity flag on or off?

[D-side]

@VaelVictus that would be, admittedly, stretching MySQL's purpose, but for lack of functional indexes, both versions (wrt. case insensitivity) can be stored and indexed instead. Or a separate search server like ElasticSearch could be used for this purpose instead.