Question

I’m having trouble finding resources for my specific problem, or at least I don’t understand the resources I am finding.

I need my Sinatra app to be able to query a remote MySQL db and return some data. I have read-only access to the db so all I need to do is retrieve it. I know the db works, my connection works, and the query I’m trying to use works. Here is some sample code:

db = ActiveRecord::Base.establish_connection(
  adapter:  'mysql', 
  host:     host, 
  database: database,
  username: user,
  password: pass)

Then I’m trying to query the connection with something like this

@courses = db.find_by_sql("SELECT *")

but the db object doesn’t have the find_by_sql method, or indeed any methods that seem like they’d do the job. Am I missing a step or something to get to where I can query the db or is it something else?

Answer 1

I don’t know what the return value of establish_connection is. I suspect it is probably not what you want. The normal way to run find_by_sql is:

ActiveRecord::Base.find_by_sql(...)

If you have a model already you can also do:

MyModel.find_by_sql(...)

Another way is to directly access the connection adapter object and call execute on it:

ActiveRecord::Base.connection.execute(...)