Rails, how to sanitize SQL in find_by_sql - ruby-on-rails

Question

Is there a way to sanitize sql in rails method find_by_sql?
I've tried this solution:
Ruby on Rails: How to sanitize a string for SQL when not using find?
But it fails at
Model.execute_sql("Update users set active = 0 where id = 2")
It throws an error, but sql code is executed and the user with ID 2 now has a disabled account.
Simple find_by_sql also does not work:
Model.find_by_sql("UPDATE user set active = 0 where id = 1")
# => code executed, user with id 1 have now ban
Edit:
Well my client requested to make that function (select by sql) in admin panel to make some complex query(joins, special conditions etc). So I really want to find_by_sql that.
Second Edit:
I want to achieve that 'evil' SQL code won't be executed.
In admin panel you can type query -> Update users set admin = true where id = 232 and I want to block any UPDATE / DROP / ALTER SQL command.
Just want to know, that here you can ONLY execute SELECT.
After some attempts I conclude sanitize_sql_array unfortunatelly don't do that.
Is there a way to do that in Rails??
Sorry for the confusion..

Answer 1

Try this:
connect = ActiveRecord::Base.connection();
connect.execute(ActiveRecord::Base.send(:sanitize_sql_array, "your string"))
You can save it in variable and use for your purposes.

Answer 2

I made a little snippet for this that you can put in initializers.
class ActiveRecord::Base
def self.escape_sql(array)
self.send(:sanitize_sql_array, array)
end
end
Right now you can escape your query with this:
query = User.escape_sql(["Update users set active = ? where id = ?", true, params[:id]])
And you can call the query any way you like:
users = User.find_by_sql(query)

Answer 3

Slightly more general-purpose:
class ActiveRecord::Base
def self.escape_sql(clause, *rest)
self.send(:sanitize_sql_array, rest.empty? ? clause : ([clause] + rest))
end
end
This one lets you call it just like you'd type in a where clause, without extra brackets, and using either array-style ? or hash-style interpolations.

Answer 4

User.find_by_sql(["SELECT * FROM users WHERE (name = ?)", params])
Source: http://blog.endpoint.com/2012/10/dont-sleep-on-rails-3-sql-injection.html

Answer 5

Though this example is for INSERT query, one can use similar approach for UPDATE queries. Raw SQL bulk insert:
users_places = []
users_values = []
timestamp = Time.now.strftime('%Y-%m-%d %H:%M:%S')
params[:users].each do |user|
users_places << "(?,?,?,?)" # Append to array
users_values << user[:name] << user[:punch_line] << timestamp << timestamp
end
bulk_insert_users_sql_arr = ["INSERT INTO users (name, punch_line, created_at, updated_at) VALUES #{users_places.join(", ")}"] + users_values
begin
sql = ActiveRecord::Base.send(:sanitize_sql_array, bulk_insert_users_sql_arr)
ActiveRecord::Base.connection.execute(sql)
rescue
"something went wrong with the bulk insert sql query"
end
Here is the reference to sanitize_sql_array method in ActiveRecord::Base, it generates the proper query string by escaping the single quotes in the strings. For example the punch_line "Don't let them get you down" will become "Don\'t let them get you down".

Answer 6

I prefer to do it with key parameters. In your case it may looks like this:
Model.find_by_sql(["UPDATE user set active = :active where id = :id", active: 0, id: 1])
Pay attention, that you pass ONLY ONE parameter to :find_by_sql method - its an array, which contains two elements: string query and hash with params (since its our favourite Ruby, you can omit the curly brackets).