How to do a LIKE query in Arel and Rails?

问题

I want to do something like:

SELECT * FROM USER WHERE NAME LIKE '%Smith%';

My attempt in Arel:

# params[:query] = 'Smith'
User.where("name like '%?%'", params[:query]).to_sql

However, this becomes:

SELECT * FROM USER WHERE NAME LIKE '%'Smith'%';

Arel wraps the query string 'Smith' correctly, but because this is a LIKE statement it doesnt work.

How does one do a LIKE query in Arel?

P.S. Bonus--I am actually trying to scan two fields on the table, both name and description, to see if there are any matches to the query. How would that work?

回答1:

This is how you perform a like query in arel:

users = User.arel_table
User.where(users[:name].matches("%#{user_name}%"))

PS:

users = User.arel_table
query_string = "%#{params[query]}%"
param_matches_string =  ->(param){ 
  users[param].matches(query_string) 
} 
User.where(param_matches_string.(:name)\
                       .or(param_matches_string.(:description)))

回答2:

Try

User.where("name like ?", "%#{params[:query]}%").to_sql

PS.

q = "%#{params[:query]}%"
User.where("name like ? or description like ?", q, q).to_sql

Aaand it's been a long time but @cgg5207 added a modification (mostly useful if you're going to search long-named or multiple long-named parameters or you're too lazy to type)

q = "%#{params[:query]}%"
User.where("name like :q or description like :q", :q => q).to_sql

User.where("name like :q or description like :q", :q => "%#{params[:query]}%").to_sql

回答3:

Reuben Mallaby's answer can be shortened further to use parameter bindings:

User.where("name like :kw or description like :kw", :kw=>"%#{params[:query]}%").to_sql

来源：https://stackoverflow.com/questions/4430578/how-to-do-a-like-query-in-arel-and-rails

标签

ruby-on-rails

activerecord

arel