ActiveResource and transactions

rubyonrails-talk
1

Hi

Not trying to solve a specific problem here, but have a theoretical question, anyhow… Having created a simple model/controller with the scaffold generator, I created a simple remote client based on ActiveResource. A part of this code is illegal, but illustrates what I want to accomplish:

require ‘active_resource’

class EnvironmentType < ActiveResource::Base

self.site = "[http://xxx:3001](http://xxx:3001)"

end

etypes = EnvironmentType.find(:all) puts etypes.map(&:name)

This part of the code is not legal, based on some code I found for ActiveRecord

EnvironmentType.transaction do etypes[0].name = “Prod” etypes[0].save

etypes[1].name = "Testing"
etypes[1].save
raise ActiveRecord::Rollback

end

End of illegal part…

etypes = EnvironmentType.find(:all) puts etypes.map(&:name)

Assumption is that that the names has not changed at this point…

Basically, my question is if there is some (easy) way to initiate a transaction from this remote client with the possibility of a rollback after a set of saves has been done.

OK, so maybe the best/shortest answer is that this is bad design to remotely initiate a transaction like this, but I’m gonna ask anyway :o)

Best regards, Rolf

2

Why save and then rollback? AR will rollback if validations fail.

3

Well, lets say the first save is OK, but the second save results in a validation error. Then the second save is rolled back, obviously, but then you want the whole thing to roll back. I’m talking about an actual DB transaction rollback.

I realise that the “illegal code” example that I included shows only a transaction connected to the one model. In general however, I’d like to start a block, which also starts a transaction in the DB, do some stuff on one or more model objects, save them to the DB, but if some condition should occur, be able to rollback all DB changes in the block.

I guess this is not easy to do in a general framework, since perhaps not all DBMSs has support for transactions. (I work with Sybase ASE which does have this capability.)

Best regards, -Rolf

4

Rolf Pedersen wrote in post #905743:

Well, lets say the first save is OK, but the second save results in a validation error. Then the second save is rolled back, obviously, but then you want the whole thing to roll back. I'm talking about an actual DB transaction rollback.

I realise that the "illegal code" example that I included shows only a transaction connected to the one model. In general however, I'd like to start a block, which also starts a transaction in the DB, do some stuff on one or more model objects, save them to the DB, but if some condition should occur, be able to rollback all DB changes in the block.

I guess this is not easy to do in a general framework, since perhaps not all DBMSs has support for transactions. (I work with Sybase ASE which does have this capability.)

Best regards, -Rolf

Rolf, i have the same question.

You solve this?

Thanks in advance, Evaldo.

5

Rolf Pedersen wrote in post #905743:

Well, lets say the first save is OK, but the second save results in a validation error. Then the second save is rolled back, obviously, but then you want the whole thing to roll back. I'm talking about an actual DB transaction rollback.

...

Best regards, -Rolf

Rolf, i have the same question.

You solve this?

google "rails transaction"

6

Scott Ribe wrote in post #1143072: