Rails, how to sanitize SQL in find_by_sql

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".