In Rails 5, how do I write a finder "like" query on a member field?

Question

I'm using Rails 5. How do I have this model ...

class Book < ApplicationRecord

has_one :author

The author class has an attribute "name". How do I write a query for book objects whose author contains the string "Joe"? I tried this

Book.includes(:author).where(:author => [ "LOWER(name) LIKE :search", :search[Dch => "%joe%"])

but no dice.

Answer 1

Try with:

Book.joins(:author).where('LOWER(authors.name) LIKE ?', '%joe%')

The plural_table_name.column_name LIKE ... syntax should work.

You can't use hash parameters to call where in this case, since you're using the LIKE operator for your query.

Notice I've changed your includes to joins since I don't know if you're going to invoke the "child" columns once having the result of your query. joins is enough to add an INNER JOIN clause and gain access to the author columns.