Forum: Ruby on Rails ActiveRecord: Getting table names

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Rahul B. (Guest)
on 2006-06-02 22:13
How do i get (discover) all the table names within a database using
ROR/ActiveRecord ?

I wish to build a webapp that connects to a database on the fly,
discovers tables and column names etc and then can show data or build a
report based on user selection. The ActiveRecord API doesnt seem to give
any method for getting table names.
Ioana K. (Guest)
on 2006-06-02 23:27
(Received via mailing list)
Maybe you should take a look at ActiveRecord::ConnectionAdapters (MySql,
Postgres, SQLServer....) on RoR  api. If u hadnt till now.
Vince Nibler (Guest)
on 2006-06-03 05:27
(Received via mailing list)
The <connection>.tables method returns an array of tables.  The
connection
is accessible via your model classes, or instances - i.e.
<ModelClass>.connection, or <any model instance>.connection.

In the API docs, you will find the "tables" method documented for DB2
and
SQLserver, but the method is annotated in the MySql and Postgres
adapters
with #:nodoc:
Rahul B. (Guest)
on 2006-06-03 08:18
Thanks a lot. Does this mean that in order to write a generic database
browser like application I would have to hardcode database specific
Select statements to retrieve tables, and other information.

Yes, as far as mysql and others, the methods don't even exist (I am
looking at:http://api.rubyonrails.org/). Where did you see the %:nodoc?

Even OG and DBI dont seem to have anything generic.

rahul benegal

Vince Nibler wrote:

> In the API docs, you will find the "tables" method documented for DB2
> and
> SQLserver, but the method is annotated in the MySql and Postgres
> adapters
> with #:nodoc:
Vince Nibler (Guest)
on 2006-06-03 13:54
(Received via mailing list)
No.  The method is there for MySQL and Postgres, just not documented
because
of the annotation.  Take a look at the mysql_adapter.rb code in your
ruby
gems activerecord directory.  On my windows box, it's here:

C:\ruby\lib\ruby\gems\1.8\gems\activerecord-
1.14.2\lib\active_record\connection_adapters
   (let me know if you need help finding it on a mac)

For the four adapters mentioned - mysql, postgres, db2 and sqlserver -
the
tables method is implemented.  You'll have to take a look for the other
adapters (just checked, it's implemented for Oracle too).  Probably easy
enough to implement for any others, given all of those examples (they're
all
pretty short, too)

Keep us posted.  It would be great to have a rails plugin to admin
databases
in liu of phpmyadmin or phppgadmin.

Vince
Rahul B. (Guest)
on 2006-06-04 08:32
Actually phpmyadmin was an example. I had once written a report
generator in Java that could generate complex reports such as
multi-level cross-tabs etc. However, the problem was that each time a
report was generated, the server had to be rebooted since new classes
were also created.

Moving to Ruby and ROR, i was looking for what i could do that would be
interesting, and i thought i could redo that in ruby. With ruby's
non-strict typing and other features, i thought i would be easier. Plus,
it didnt look like rails has a report generator (at least when i played
with rails last year).

However, a rails/ruby application (plugin???) like phpmyadmin would be
interesting also.

Rahul Benegal

Vince Nibler wrote:
>
> Keep us posted.  It would be great to have a rails plugin to admin
> databases
> in liu of phpmyadmin or phppgadmin.
>
> Vince
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