I want to save to a log file some SQL query rails performs, (namely the CREATE, UPDATE and DELETE ones) therefore I need to intercept all queries and then filter them maybe with some regexp and log them as needed.
Where would I put such a thing in the rails code?
Here a simplified version of what c0r0ner linked to, to better show it:
connection = ActiveRecord::Base.connection
class << connection
alias :original_exec :execute
def execute(sql, *name)
# try to log sql command but ignore any errors that occur in this block
# we log before executing, in case the execution raises an error
begin
File.open(Rails.root.join("/log/sql.txt"),'a'){|f| f.puts Time.now.to_s+": "+sql}
rescue Exception => e
;
end
# execute original statement
original_exec(sql, *name)
end
end
application.rb, in there you could require a file containing your override code. (On Rails 2, you're stuck with the environment config files.)SQL logging in rails - In brief - you need to override ActiveRecord execute method. There you can add any logic for logging.
As a note for followers, you can "log all queries" like Rails - See generated SQL queries in Log files and then grep the files for the ones you want, if desired.
If you are using mysql I would look into mysqlbinlog . It is going to track everything that potentially updates data. you can grep out whatever you need from that log easily.
SQL Server? If so...
Actually, I'd do this at the SQL end. You could set up a trace, and collect every query that comes through a connection with a particular Application Name. If you save it to a table, you can easily query that table later.
Slightly updated version of @luca's answer for at least Rails 4 (and probably Rails 5)
Place this in config/initializers/sql_logger.rb:
connection = ActiveRecord::Base.connection
class << connection
alias :original_exec :execute
def execute(sql, *name)
# try to log sql command but ignore any errors that occur in this block
# we log before executing, in case the execution raises an error
begin
File.open(Rails.root.join("log/sql.log"), 'a') do |file|
file.puts Time.now.to_s + ": " + sql
end
rescue Exception => e
"Error logging SQL: #{e}"
end
# execute original statement
original_exec(sql, *name)
end
end
