Create reports with ActiveRecord to download by user

rubyonrails-talk
1

Hi -

I want to enable the user to generate a report based on the database used by the application. I have a few related questions:

1. Assuming my script is called 'create_report.rb' and stored under /lib/tasks, how do I execute it from my controller once the user clicked the link? I read that 'send_file' is probably what I want.

2. ActiveRecord is great (statement), and I want to use it in this script. Do I need to require 'activerecord' or anything in the actual file? I would like to use AR much like I do in my views (@users = User.find(:all), user.full_name, etc.) - Does it just work or do I need to somehow load the existing models to memory.

3. where is the logical place on the server to store files I create (if there is one)? I was thinking /public/files/ or something, or even outside my application root.

3. for the sake of example, I want to return a csv file containing all users and their birthdays: http://pastie.org/410902

It's very incomplete, but I'm hoping someone can point me in the right direction... thanks.

2

Hi -

I want to enable the user to generate a report based on the database used by the application. I have a few related questions:

1. Assuming my script is called 'create_report.rb' and stored under /lib/tasks, how do I execute it from my controller once the user
clicked the link? I read that 'send_file' is probably what I want.

2. ActiveRecord is great (statement), and I want to use it in this script. Do I need to require 'activerecord' or anything in the actual file? I would like to use AR much like I do in my views (@users = User.find(:all), user.full_name, etc.) - Does it just work or do I
need to somehow load the existing models to memory.

So either you create a file somewhere on disk and use send_file (or
one of the speedier alternatives) (the file doesn't have to be in / public, bear in mind that anyone can get files from there) or you
create the data in ram and use send_data.

If your report generation is a standalone process then you have to
worry about setting up the right environment, but you may not need to
do that - you could call the report code directly from your app (or to
put things another way 'report code' is just the same as normal code).

Fred

3

Hi -

I want to enable the user to generate a report based on the database used by the application. I have a few related questions:

1. Assuming my script is called 'create_report.rb' and stored under /lib/tasks, how do I execute it from my controller once the user clicked the link? I read that 'send_file' is probably what I want.

lib/tasks is for rake tasks. You should either remake your script to rake task (and then execute it using Rake::Task["task_name"].invoke) or put it to lib and then execute it by calling method from it.

2. ActiveRecord is great (statement), and I want to use it in this script. Do I need to require 'activerecord' or anything in the actual file? I would like to use AR much like I do in my views (@users = User.find(:all), user.full_name, etc.) - Does it just work or do I need to somehow load the existing models to memory.

If you're using script from lib folder, then it has full access to rails, your models and etc.

3. where is the logical place on the server to store files I create (if there is one)? I was thinking /public/files/ or something, or even outside my application root.

I'd suggest somewhere outside public, maybe /reports?

4

There are so many little decisions. :slight_smile:

1.) I have found it good for me to create a method in a controller to create, and store the report. Reports of the same type go in the same controller. For example, I have reports that are “weekly”, “monthly”, “quarterly”, and “fiscal year”. There are reports for single users, groups (of users) and accounts (groups of "groups). This tends to proliferate controllers, but it does tend to keep them short. So, there is an ActiveUserUsageReport.rb that has a weekly methods, quaterly method, etc. At a first past, I put the sql directly in the method, essentially find_by_sql. But after all tests pass, I create a database stored procedure and move the sql code there. I try to do as much of the data massaging in the database. But, YMMV. My database is highly normalized, which tends to subvert the needs for reporting. I don’t have the time to create a reporting database which flattens out the structure.

2.) I find that my sql’s for reports get too complicated to try to use AR all the time. Pushing SQL’s into the database works best for me. BTW, I use postgres.

3). This can get interesting. Whereever you put the report output it has to be a place that the rails process has access to. I have found, for example, on my own ubuntu 8.10 the running rails process needs to have envirenment.rb owned by www-data (the apache process actually running). www-data, then, needed to be able to read and write to whatever file system I choose to store reports. I actually use app/reports to store them. The directory is swept by a cron job to remove old reports. I provide reports in comma-delimted format as well as .png for the graphs. This reports are created and then spooled back to the user. There is an html option to see the report “on-line” as it were, so I work with end users to keeps as much of the html display “row oriented” to cut down on the number of, or type of views.

Naming reports is an issue as well. User reports have to be tied to the users, groups to groups, etc.I currently use, for a user for example, username.reporttype.datetime. However, you get users who are forever changing the start date and end date of the report and rerunning it over and over. Hence, the need for the cron job to clean up from time to time. Stored procedures (actually functions) inside postgres handles repeated reports very well, since the function is compiled only once, but is used again and again.

This is what I have worked out over time.

HTH

Charles