# Newbie needing help on Legacy DB Rails Concepts

**URL:** <https://www.ruby-forum.com/t/newbie-needing-help-on-legacy-db-rails-concepts/153188>\
**Category:** Rails\
**Created:** [November 13, 2008, 2:49am UTC](https://www.ruby-forum.com/t/newbie-needing-help-on-legacy-db-rails-concepts/153188 "2008-11-13T02:49:40Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Auch](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/bb73d2/32.png) [@Auch](https://www.ruby-forum.com/u/Auch)\
**Post date:** [November 13, 2008, 2:49am UTC](https://www.ruby-forum.com/t/newbie-needing-help-on-legacy-db-rails-concepts/153188/1 "2008-11-13T02:49:40Z")

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Hi

I have limited success with rails and am trying very hard to  
understand the MVC, DRY and RESTful concepts that Rails supports.

What I am trying to do is to automate some data manipulation  
procedures for legacy systems. I have three tables that I need to  
import into the Rails application.

Table 1  
Legacy\_System\_ID1, Agency\_Business\_Number, Agency\_Name  
belongs to Table 3  
belongs to Table 1

Table 2  
Legacy\_System\_ID2, Legacy\_System\_ID1, Legacy\_System\_Contact\_ID,  
Agency\_Business\_Number, Agency\_name  
has many Table 1

Table 3  
Agency\_Business\_Number, Agency\_Name.  
has many Table 1

These files are all in csv format. What I am having trouble with is  
the concept of primary key ids. Rails does not like primary keys that  
are not incremental. I know I can set the primary key to  
Legacy\_System\_ID1 in Table 1 and set the foreign key to the same ID in  
Table 2.

The pinch is that I need to seperate the contact\_ID from the  
Legacy\_System\_ID2 of Table 2 into two tables and also add new entries  
into Table 3, which is essentially a subset of Table 1 to keep track  
of which Agencies with unique Agency\_Business\_Numbers are registered.

Whats the best way to go about this in Rails? I am experimenting with  
Instant Rails 2.02

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<div class="post-metadata">

**Author:** ![Auch](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/bb73d2/32.png) [@Auch](https://www.ruby-forum.com/u/Auch)\
**Post date:** [November 13, 2008, 4:49am UTC](https://www.ruby-forum.com/t/newbie-needing-help-on-legacy-db-rails-concepts/153188/2 "2008-11-13T04:49:01Z")

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On Nov 13, 11:10 am, Auch [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Legacy\_System\_ID1, Agency\_Business\_Number, Agency\_Name  
> has many Table 1  
> of which Agencies with unique Agency\_Business\_Numbers are registered.
> 
> Whats the best way to go about this in Rails? I am experimenting with  
> Instant Rails 2.02

I think your model is saying something like  
System contact (a person) “has many” Agencies  
in a nutshell right?

–  
Daniel B.

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<div class="post-metadata">

**Author:** ![Auch](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/bb73d2/32.png) [@Auch](https://www.ruby-forum.com/u/Auch)\
**Post date:** [November 13, 2008, 5:45am UTC](https://www.ruby-forum.com/t/newbie-needing-help-on-legacy-db-rails-concepts/153188/3 "2008-11-13T05:45:42Z")

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Hi Daniel

Thanks for replying so quickly. In a nutshell, yes. An Agency has many  
People. Essentially the purpose of the project is to perform an  
interim admin function to sync two systems. Hence there are two sets  
of Primary keys and two tables. The third table is the output, where  
it records the Agency business number to ensure that the Agency is  
registered. Obviously there will be multiple Agency profiles for the  
two systems with the primary keys for the agencies. Currently this is  
being done manually.

What I want to find out now is how to generate the view to encompass  
the values from all three tables into one view, when I am using one of  
the two system generated lists as a list for users to determine if a  
client has been registered or not. E.g

Agency ID 2 is clicked, which is linked to only one Agency Business  
Number. How do I represent the values for this Agency ID 2 from the  
other two tables? Obviously some Agency IDs will not have a  
corresponding Agency Business Number in table 3 as they have not been  
registered as yet, or in Table 2 for that matter. I am envisaging the  
use of partials.

I worked out how to generate primary and foreign keys. Currently I  
have some code in my model that does this, but is not the best.

Upload Model  
def self.save  
FasterCSV.foreach("D:/Rails/MySql/Migration/file.csv) do |row|  
unless Agency\_ID1.exists?(row[0])  
agency = Agency.new(:OrganisationName=\>row[1],:TPID=\>row[3]) do  
|i|  
i.Agency\_ID1 = (row[0])  
end  
agency.save  
end  
unless person.exists?(row[5])  
contact = person.new(:ContactFname=\>row[6],:ContactLname=\>row  
[7],:ContactPhone=\>row[8],  
:ContactFax=\>row[9],:ContactEmail=\>row[10]) do |si|  
i.ContactID = (row[5])  
end  
contact.save  
end  
end  
end

It’s meant to be interim code that helps me load primary key values.

I also have a search function working with Acts\_as\_ferret.

This is the model code for Agency 2 (list)

acts\_as\_ferret :fields =\> [:OrganisationName]

This is the controller

class SearchesController \< ApplicationController  
def index  
if params[:q]  
query = params[:q]  
@Agency2 = Agency\_ID2.find\_with\_ferret query, :page =\> params  
[:page], :per\_page =\> 50  
end  
end  
end

This is the view in views/searches

 \<% @sbtradesuppliers.each do |s| %\> \<% end %\> 

| OrganisationName | smartbuy ID | Supplier ABN | Supplier TPID |
| \<%= link\_to s.OrganisationName, Agency2\_path(s.id) %\> | \<%= s.Agency Business Number%\> | \<%= s.Agency ID 2%\> |

  
  
  
\<%= will\_paginate @Agency2 %\>

My last question is, is this restful?

Any help would be much appreciated.

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<div class="post-metadata">

**Author:** ![Auch](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/bb73d2/32.png) [@Auch](https://www.ruby-forum.com/u/Auch)\
**Post date:** [November 13, 2008, 8:17am UTC](https://www.ruby-forum.com/t/newbie-needing-help-on-legacy-db-rails-concepts/153188/4 "2008-11-13T08:17:50Z")

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I can’t grasp the situation but it just seems to me that if you’re  
migrating old data  
into a new system going forward, you should probably massage it  
and get it normalized and put it into the database in one hit.  
The best swiss army knives I know  
of are spreadsheets (and all their functions) and databases (sql and  
large data sets) for sorting this sort of stuff out.  
Rails isn’t necessarily the best way to do it although it might help  
in some situations.

Surely table 3 and table 1 should be combined, shouldn’t they?  
You don’t want 2 tables of agencies. You just want one and you can  
tell which are registered by the fact that they do or don’t have a  
number against them. Merging table 3 into 1 might be the first  
thing. If registration is more complex than that, then you may have  
to set up more tables and associations to model it appropriately.

Table 2 is already linked to table 1 via legacy ID1 - assuming these  
id’s are ok.  
So I’d get table2 into the database; pull out unique list of system  
contacts and create  
a separate table ‘system\_contacts’ (I’m assuming you’ve got some  
other fields to put against them). Table 2 then becomes a joining  
table. It already has the two fk’s - which you might relabel as  
agency\_id and system\_contact\_id.

Once this is done, you’ll have 3 tables and 3 models and using them  
would be a basic rails exercise.  
I probably haven’t grasped the full complexity of the relationships  
here, so I’ll stop there.

–  
Daniel B.

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<div class="post-metadata">

**Author:** ![Auch](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/bb73d2/32.png) [@Auch](https://www.ruby-forum.com/u/Auch)\
**Post date:** [November 13, 2008, 11:39am UTC](https://www.ruby-forum.com/t/newbie-needing-help-on-legacy-db-rails-concepts/153188/5 "2008-11-13T11:39:22Z")

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So you need a join table that contains: LEGACY\_SYSTEM\_ID2 |  
CONTACT\_ID : as fields in which the two fields do NOT use the same ID?