Comments on: Lost in multiple rails? http://blog.amber.org/2005/06/30/lost-in-multiple-rails/ Thoughts of a minor lunatic Fri, 29 Aug 2008 23:01:26 +0000 http://wordpress.org/?v=2.6.1 By: Dorival Pedroso http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-39848 Dorival Pedroso Mon, 06 Nov 2006 20:22:54 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-39848 I have the same situation as *Chris*. It would be nice to have a clean way to to that. Thanks. I have the same situation as Chris. It would be nice to have a clean way to to that. Thanks.

]]> By: MikeW http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-38373 MikeW Wed, 01 Nov 2006 04:31:44 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-38373 I'm running into an issue with relationships across multiple databases. I have 2 different applications in place running on 2 different databases. Everything is working just fine, though I had to fix an issue with it. The same issue I'm about to get to. I now want to add a third application that interacts with both applications. The first app is an inventory control program that runs locally at the company. This is in case the internet ever goes down, which unfortunately happens on occasion, they can still operate. Next is a site served elsewhere for their sales reps to use. Everything in that database is stored on the web server, except for the user table which already exists on the company database. A problem occured when using code like this: @customer.users where a User habtm Customers. The error that I got indicated that the linker table didn't exist in the database that the users were stored in. But when I switched the order of the code: @user.customers it worked. So this must mean that I can never call a method on a model that is stored in one database and include a model from another database, which will essentially kill any possibilities of eager loading information. I was able to bypass the issue in the first scenario, but now with my third application, it will be interacting a lot between the two databases. About half will be in one database, half in another. Is there a better way of approaching this problem, or a way to get around this issue? Or am I just doomed to having to pulling in tons of information and having to work with is server side? I’m running into an issue with relationships across multiple databases. I have 2 different applications in place running on 2 different databases. Everything is working just fine, though I had to fix an issue with it. The same issue I’m about to get to. I now want to add a third application that interacts with both applications. The first app is an inventory control program that runs locally at the company. This is in case the internet ever goes down, which unfortunately happens on occasion, they can still operate. Next is a site served elsewhere for their sales reps to use. Everything in that database is stored on the web server, except for the user table which already exists on the company database. A problem occured when using code like this:

@customer.users

where a User habtm Customers. The error that I got indicated that the linker table didn’t exist in the database that the users were stored in. But when I switched the order of the code:

@user.customers

it worked. So this must mean that I can never call a method on a model that is stored in one database and include a model from another database, which will essentially kill any possibilities of eager loading information.

I was able to bypass the issue in the first scenario, but now with my third application, it will be interacting a lot between the two databases. About half will be in one database, half in another. Is there a better way of approaching this problem, or a way to get around this issue? Or am I just doomed to having to pulling in tons of information and having to work with is server side?

]]> By: petrilli http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-35960 petrilli Sat, 21 Oct 2006 02:11:06 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-35960 Actually, Erwan, what you do is attach your classes to the database directly. So if you had a class "Foo" that needed to be retrieved from the non-default database, you would use: Foo.establish_connection ... Like that. Actually, Erwan, what you do is attach your classes to the database directly. So if you had a class “Foo” that needed to be retrieved from the non-default database, you would use:

Foo.establish_connection …

Like that.

]]> By: Erwan http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-35145 Erwan Thu, 19 Oct 2006 03:01:23 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-35145 there is no ActiveRecord::Base.establish_connection line in my environment.rb file... where could I find it ? there is no ActiveRecord::Base.establish_connection line in my environment.rb file… where could I find it ?

]]> By: Chris http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-28542 Chris Tue, 12 Sep 2006 21:02:50 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-28542 I'm trying out rails on a new app for multiple customers where each customer will have a seperate database of 38 tables. I need a clean method of selecting a database based on user input on the login form. For example if the user is not logged in already they will be presented with a form containing fields for username, password, and account. The account name will corrispond to the database that they should be accessing and their username and password will then be validated in a user table in that same database. Is there a clean way to do this where I don't have to add each database to the database.yml? We hoping for around 100 customers for this app. I’m trying out rails on a new app for multiple customers where each customer will have a seperate database of 38 tables. I need a clean method of selecting a database based on user input on the login form. For example if the user is not logged in already they will be presented with a form containing fields for username, password, and account. The account name will corrispond to the database that they should be accessing and their username and password will then be validated in a user table in that same database. Is there a clean way to do this where I don’t have to add each database to the database.yml? We hoping for around 100 customers for this app.

]]> By: lightsedge http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-23034 lightsedge Tue, 15 Aug 2006 02:26:16 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-23034 See p65 of Rails Recipes by Chad Fowler See p65 of Rails Recipes by Chad Fowler

]]> By: Patrick http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-7411 Patrick Thu, 18 May 2006 21:37:51 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-7411 I just came across an interesting problem while trying this out. I have five tables I need to access in my rails app. Three are in Oracle and two are in PostgreSQL. I first had the Oracle tables extend an ActiveRecord::Base subclass named Auth so that in environment.rb I could just write: Auth.establish_connection "auth_#{ENV["RAILS_ENV"]}" This worked well, and only one connection to Oracle was created. However, I then tried to do the same with my PostgreSQL models, creating an ActiveRecord::Base subclass named Dns, and the following line in environment.rb: Dns.establish_connection "dns_#{ENV["RAILS_ENV"]}" This didn't work so well, and I'm not sure if the problem is in the Oracle adapter or the PostgreSQL adapter. The issue is that the PostgreSQL adapter complains that it can't find a table named "dns". The only reason I'm using subclassing is as a hack to not have to specify the database connection used by every model class, which causes a different connection to be used for each one, which prevents any sort of transactional behavior between those models and wastes database resources. In the end, what I'm doing is the following in environment.rb: Record.establish_connection "dns_#{ENV["RAILS_ENV"]}" Redirect.connection = Record.connection This seems kind of nasty, but at least it gives me just one connection. I'd like to see a cleaner solution, but it's something you can use if you run into the same situation. I just came across an interesting problem while trying this out. I have five tables I need to access in my rails app. Three are in Oracle and two are in PostgreSQL.

I first had the Oracle tables extend an ActiveRecord::Base subclass named Auth so that in environment.rb I could just write:

Auth.establish_connection “auth_#{ENV[“RAILS_ENV”]}”

This worked well, and only one connection to Oracle was created.

However, I then tried to do the same with my PostgreSQL models, creating an ActiveRecord::Base subclass named Dns, and the following line in environment.rb:

Dns.establish_connection “dns_#{ENV[“RAILS_ENV”]}”

This didn’t work so well, and I’m not sure if the problem is in the Oracle adapter or the PostgreSQL adapter.

The issue is that the PostgreSQL adapter complains that it can’t find a table named “dns”. The only reason I’m using subclassing is as a hack to not have to specify the database connection used by every model class, which causes a different connection to be used for each one, which prevents any sort of transactional behavior between those models and wastes database resources.

In the end, what I’m doing is the following in environment.rb:

Record.establish_connection “dns_#{ENV[“RAILS_ENV”]}”
Redirect.connection = Record.connection

This seems kind of nasty, but at least it gives me just one connection. I’d like to see a cleaner solution, but it’s something you can use if you run into the same situation.

]]> By: Workin’ on it. » Rubicizing http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-6318 Workin’ on it. » Rubicizing Wed, 19 Apr 2006 03:34:33 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-6318 [...] Now that this things working, it’s time to break it. In my very first iteration I created the app with a single db, but in reality - it’s going to span two. Today I needed to figure out exactly how this is done. From what I read, this is something that is quite possible… but just isn’t all that straight forward. [...] [...] Now that this things working, it’s time to break it. In my very first iteration I created the app with a single db, but in reality – it’s going to span two. Today I needed to figure out exactly how this is done. From what I read, this is something that is quite possible… but just isn’t all that straight forward. [...]

]]> By: petrilli http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-5329 petrilli Thu, 09 Feb 2006 21:06:40 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-5329 There is actually a "good introductory article":http://wiki.rubyonrails.org/rails/pages/HowtoUseMultipleDatabases in the Rails wiki on how to do this. It worked fine for me, though it's perhaps not the way I would have approached the problem. There is actually a good introductory article in the Rails wiki on how to do this. It worked fine for me, though it’s perhaps not the way I would have approached the problem.

]]> By: Deniz http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-5327 Deniz Thu, 09 Feb 2006 18:23:24 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-5327 Hi, Since I am very new to RoR, there are a lot of things I don't know. I am very confused about connecting multiple databases from one application. My application works great for single database and I came to a point that I am required to connect a second database and pull some information and return results. I still have no idea how to do this yet, could you by chance explain this a little more on your blog.. Thank you Deniz. Hi,
Since I am very new to RoR, there are a lot of things I don’t know. I am very confused about connecting multiple databases from one application. My application works great for single database and I came to a point that I am required to connect a second database and pull some information and return results.
I still have no idea how to do this yet, could you by chance explain this a little more on your blog..
Thank you
Deniz.

]]> By: Louis http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-3459 Louis Sat, 01 Oct 2005 19:44:12 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-3459 Thanks so much for your comment, Michael. Step 2 was just what I needed to clarify the API docs on establish_connection. (Woot. The hardest part with Rails is trying to do things "right" :p Once you know how, it seems so obvious ... Sigh.) Thanks so much for your comment, Michael. Step 2 was just what I needed to clarify the API docs on establish_connection. (Woot. The hardest part with Rails is trying to do things “right” :p Once you know how, it seems so obvious … Sigh.)

]]> By: petrilli http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-2068 petrilli Fri, 01 Jul 2005 04:07:57 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-2068 Wow, I'm flattered. Thanks for the pointer Michael. I had gotten some leads from @tufty@ on @#rubyonrails@ and had started to go there, unfortunately I've run smack into some scaffold problems. It is late, and I just got back, so I will post about them more tomorrow. The solution you gave is a bit more elegant, and solves that problem. Now I just have to figure out how to solve my scaffold problem. Wow, I’m flattered. Thanks for the pointer Michael. I had gotten some leads from tufty on #rubyonrails and had started to go there, unfortunately I’ve run smack into some scaffold problems. It is late, and I just got back, so I will post about them more tomorrow.

The solution you gave is a bit more elegant, and solves that problem. Now I just have to figure out how to solve my scaffold problem.

]]> By: Michael Koziarski http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-2067 Michael Koziarski Thu, 30 Jun 2005 22:01:34 +0000 http://blog.amber.org/2005/06/30/lost-in-multiple-rails/#comment-2067 Hey there, You've actually got a few of the core rails team reading your blog. Your 'the red herring of performance' piece led a lot of us to subscribe. So, here's some help: 1) Edit database.yml and add the configuration for your second database. Just like the others, but instead of using the environment as the key, use some other name 2) You want to make the Course.establish_connection call in your environment.rb file, just under the ActiveRecord::Base.establish_connection Course.establish_connection "your_config_name" And if you wanted per-environment options for the second database, just call them something like "your_config_name_production" and call Course.establish_connection "your_connection_name#{RAILS_ENV}" Hey there,

You’ve actually got a few of the core rails team reading your blog. Your ‘the red herring of performance’ piece led a lot of us to subscribe.

So, here’s some help:

1) Edit database.yml and add the configuration for your second database. Just like the others, but instead of using the environment as the key, use some other name

2) You want to make the Course.establish_connection call in your environment.rb file, just under the ActiveRecord::Base.establish_connection

Course.establish_connection “your_config_name”

And if you wanted per-environment options for the second database, just call them something like “your_config_name_production” and call Course.establish_connection “your_connection_name#{RAILS_ENV}”

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