RoR with Existing tables in database using Postgresql

Hi,

I am new bee to Rais. I need to create a Rails application with existing
database with several number of tables. When i came across web, I didn’t
find any fruitful ideas for developing application using existing
tables.
Everything i found was to create new database with Create, Edit, Insert
feature. I need to create a application using existing postgresql
database
stuffed with tables where i have to provide view only permission to the
user. Kinldy help me in this regard. I have 15 tables in my database
which
developed in postgresql. Advance thanx to my friends of RoR-Talk.

With Regards,
Palani Kannan. K

Start with googling ‘rails legacy database’ for ideas.

Providing only ‘read access’ simply means your rails application should
not accept any new/create/update requests, and there are numerous ways
to defend against this.

On Fri, 03 Sep 2010 12:16:26 +0200, PalaniKannan K wrote:

friends of RoR-Talk. –
Hi Palani,

you might find this helpful:

http://www.theirishpenguin.com/2009/11/26/generate-rails-migrations-from-
your-postgresql-or-mysql-database/

richard,

On 3 September 2010 16:08, Ar Chron [email protected] wrote:

Start with googling ‘rails legacy database’ for ideas.

Yaa… I will use this hint. Thank You.

Providing only ‘read access’ simply means your rails application should
not accept any new/create/update requests, and there are numerous ways
to defend against this.

Can you please tell me the ways… It will be useful to me. Tanx
advance.


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With Regards
Palani Kannan. K
Office: +49-531-2616-226
Mobile: +4917647098166

On Fri, Sep 3, 2010 at 8:59 AM, PalaniKannan K [email protected]
wrote:

I feel that, this is same kind of results I got in google search… Creating
model using dumped schemas of existing table. but, its not working.

“its not working” isn’t particularly useful information.

So you have an existing table, say “things”. You create a model for
it, e.g.

class Thing < ActiveRecord::Base
end

Done. Maybe you have to tell it there’s a non-Rails-standard index
field, etc., but basically that’s it. There’s no reason to be fooling
with
migrations if you have an existing table, unless you can and want to
do transformations on them to make them more Rails-like.

So what have you tried, and what’s the actual problem?


Hassan S. ------------------------ [email protected]
twitter: @hassan

On 3 September 2010 16:21, Richard H. [email protected]
wrote:

On Fri, 03 Sep 2010 12:16:26 +0200, PalaniKannan K wrote:

Hi,

I am new bee to Rais. I need to create a Rails application with existing
database with several number of tables. When i came across web, I didn’t
find any fruitful ideas for developing application using existing
tables. Everything i found was to create new database with Create, Edit,
Insert feature. I need to create a application using existing postgresql
database stuffed with tables where i have to provide view only
permission to the user. Kinldy help me in this regard. I have 15 tables
in my database which developed in postgresql. Advance thanx to my
friends of RoR-Talk. –

Hi Palani,

you might find this helpful:

I feel that, this is same kind of results I got in google search…
Creating
model using dumped schemas of existing table. but, its not working.

http://www.theirishpenguin.com/2009/11/26/generate-rails-migrations-from-
your-postgresql-or-mysql-database/http://www.theirishpenguin.com/2009/11/26/generate-rails-migrations-from- your-postgresql-or-mysql-database/

richard,


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With Regards
Palani Kannan. K
Office: +49-531-2616-226
Mobile: +4917647098166

On Fri, Sep 3, 2010 at 11:18 AM, PalaniKannan K
[email protected] wrote

Realy Sorry… If my problem was not understandable. I am a new bee… there
is no perfect tutorials available for already existing tables to develop web
interface. In before cases I used cgi and perl. Now I started ruby and RoR.
I feel its totally different from cgi. If you know any turorials with
examples, kindly tell me. In previously mentioned link, I am unable to
understand.

The earlier link was irrelevant, ignore it. The advice to google “rails
legacy database” from Ar Chron should help, though.

In any case, make a copy of your existing DB and point your Rails
app at it.

Create a model based on an existing table e.g. “things”, as in

class Thing < ActiveRecord::Base
end

Then start a console and type

thing = Thing.first

Look at the result. That should get you started :slight_smile:

And no, sorry, I don’t know of any specific tutorials on doing this. It
would probably be easier if you’d already developed at least a trivial
green-field Rails app (gone through the basic tutorials, guides, etc.)

FWIW, and good luck,

Hassan S. ------------------------ [email protected]
twitter: @hassan

On 3 September 2010 18:23, Hassan S.
[email protected]wrote:

On Fri, Sep 3, 2010 at 8:59 AM, PalaniKannan K [email protected]
wrote:

I feel that, this is same kind of results I got in google search…
Creating
model using dumped schemas of existing table. but, its not working.

“its not working” isn’t particularly useful information.

So you have an existing table, say “things”. You create a model for
it, e.g.

class Thing < ActiveRecord::Base
end

Done. Maybe you have to tell it there’s a non-Rails-standard index
field, etc., but basically that’s it. There’s no reason to be fooling with
migrations if you have an existing table, unless you can and want to
do transformations on them to make them more Rails-like.

Realy Sorry… If my problem was not understandable. I am a new bee…
there
is no perfect tutorials available for already existing tables to develop
web
interface. In before cases I used cgi and perl. Now I started ruby and
RoR.
I feel its totally different from cgi. If you know any turorials with
examples, kindly tell me. In previously mentioned link, I am unable to
understand.

So what have you tried, and what’s the actual problem?


Hassan S. ------------------------ [email protected]
twitter: @hassan


You received this message because you are subscribed to the Google G.
“Ruby on Rails: Talk” group.
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With Regards
Palani Kannan. K
Office: +49-531-2616-226
Mobile: +4917647098166

On Sep 3, 12:14 pm, Hassan S. [email protected]
wrote:

Create a model based on an existing table e.g. “things”, as in

class Thing < ActiveRecord::Base
end

Odds are, you will need to tell Rails what the primary key of your
legacy table is, unless it happens to be “id”

class Thing < ActiveRecord::Base
set_primary_key “[PKFieldName]”
end

On Fri, Sep 3, 2010 at 2:47 PM, E. Litwin [email protected]
wrote:

Odds are, you will need to tell Rails what the primary key of your
legacy table is, unless it happens to be “id”

Absolutely, and odds are the OP will encounter other grief in the form
of naming conventions/pluralization yadda yadda. :slight_smile:

But creating a model and seeing what happens and where it breaks[*]
is the best way to start, IMO. And as a matter of fact I’m currently up
to my armpits in a similar project, though I do have the leeway to do
a few Railsizations to the db schema, thankfully.

[*] by writing tests, hopefully!

FWIW,

Hassan S. ------------------------ [email protected]
twitter: @hassan

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