Rails - Aug 2006 - Query Offset Parameter problem

Greetings,

I''m trying to make a simple logging application that just displays the 
last few rows of information in the log.  In order to do this, I am 
trying to use the ":offset" option for find.  However, I am not
getting
the results I expect.

For testing purposes, the query is being run against a table (MySQL) 
that contains 11 records.  According to the RoR documentation, when I 
use the :offset parameter as shown below, I expect to get back 6 records 
instead of 11.  Am I just not reading the documentation correctly?

    # This should return all rows in the table after the fifth row
    @transactions = Transaction.find(:all, :offset => 5 )

    # Should show 6 if the total rows are 11
    puts "TOTAL ROWS RETURNED IS: " + @transactions.size.to_s

Thanks in advance for any insight or help.

Doug

-- 
Posted via http://www.ruby-forum.com/.

Doug Meharry wrote:
> Greetings,
> 
> I''m trying to make a simple logging application that just displays
the
> last few rows of information in the log.  In order to do this, I am 
> trying to use the ":offset" option for find.  However, I am not
getting
> the results I expect.
> 
> For testing purposes, the query is being run against a table (MySQL) 
> that contains 11 records.  According to the RoR documentation, when I 
> use the :offset parameter as shown below, I expect to get back 6 records 
> instead of 11.  Am I just not reading the documentation correctly?
> 
>     # This should return all rows in the table after the fifth row
>     @transactions = Transaction.find(:all, :offset => 5 )
> 
>     # Should show 6 if the total rows are 11
>     puts "TOTAL ROWS RETURNED IS: " + @transactions.size.to_s
> 
> Thanks in advance for any insight or help.
> 
> Doug
It appears MySQL also needs a ":limit" parameter specified in addition
to the ":offset" parameter.  I have not tested this issue with 
PostgreSQL or any other dbs but assume this could also apply in other 
such cases.

Doug


-- 
Posted via http://www.ruby-forum.com/.

You could use the created_at or updated_at column and do something where 
you show the most recent entries like this:

... ORDER BY updated_at DESC LIMIT 10

Don''t know if that works for your situation or not, but will give you 
similar results as what your example is trying to get.

Regards,

Michael

-- 
Posted via http://www.ruby-forum.com/.

:offset it dependent on :limit, in other words, if you don''t specify
:limit, :offset is basically ignored (look at the sql generated in
your log to see).  this is because the offset is part of the limit
clause and is optional, however, the # of rows to limit is not

select * from table ... [limit [offset,] rows]

so

select * from table ... limit 10, 20

would select limit the number of returned rows to 20 starting at row 10

hope this is clear enough for you.

Chris

On 8/8/06, Doug Meharry <doug@dmeharry.com> wrote:
> Greetings,
>
> I''m trying to make a simple logging application that just displays
the
> last few rows of information in the log.  In order to do this, I am
> trying to use the ":offset" option for find.  However, I am not
getting
> the results I expect.
>
> For testing purposes, the query is being run against a table (MySQL)
> that contains 11 records.  According to the RoR documentation, when I
> use the :offset parameter as shown below, I expect to get back 6 records
> instead of 11.  Am I just not reading the documentation correctly?
>
>     # This should return all rows in the table after the fifth row
>     @transactions = Transaction.find(:all, :offset => 5 )
>
>     # Should show 6 if the total rows are 11
>     puts "TOTAL ROWS RETURNED IS: " + @transactions.size.to_s
>
> Thanks in advance for any insight or help.
>
> Doug
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Hi,

I purchased the first edition of "Agile Web Development with Rails"
some
time back and never had a time to get into it.  I want to learn now but 
I''ve seen there''s a second edition.  Is the content in the
first edition
still relevant, or are some parts of it "depreceated" or no longer 
current?  Should I get the second edition?  What about "Rails
Receipes"
as well?

Thanks,
Rob

On 8/9/06, Rob Gabaree <lists@rawb.net> wrote:
> I purchased the first edition of "Agile Web Development with
Rails" some
> time back and never had a time to get into it.  I want to learn now but
> I''ve seen there''s a second edition.  Is the content in
the first edition
> still relevant, or are some parts of it "depreceated" or no
longer
> current?  Should I get the second edition?  What about "Rails
Receipes"
> as well?
I have the 1st edition and I don''t regret buying the 2nd edition at
all.  It''s been well worth it, even as a beta book.

Pieces of the 1st edition are deprecated, yes.

-- James

Rails Recipes is quite good too, but it is very much advanced
material for people comfortable with Rails. n00bs like me can''t
put much of it into practice, but theres a lot of nice stuff in there
- kind of a reward at the end of the journey.

On 8/9/06, James Ludlow <jamesludlow@gmail.com>
wrote:
> On 8/9/06, Rob Gabaree <lists@rawb.net> wrote:
> > I purchased the first edition of "Agile Web Development with
Rails" some
> > time back and never had a time to get into it.  I want to learn now
but
> > I''ve seen there''s a second edition.  Is the content
in the first edition
> > still relevant, or are some parts of it "depreceated" or no
longer
> > current?  Should I get the second edition?  What about "Rails
Receipes"
> > as well?
>
> I have the 1st edition and I don''t regret buying the 2nd edition
at
> all.  It''s been well worth it, even as a beta book.
>
> Pieces of the 1st edition are deprecated, yes.
>
> -- James
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

> I purchased the first edition of "Agile Web Development with
Rails" some
> time back and never had a time to get into it.  I want to learn now but
> I''ve seen there''s a second edition.  Is the content in
the first edition
> still relevant, or are some parts of it "depreceated" or no
longer
> current?  Should I get the second edition?
AFIK there are no statements in 1st deprecrated with Rails 1.1.4.

Sure, 2nd edition have majors rewrite and additions, but you can start
learning with a recent rails setup and this book.

Big enhancements in 2nd are for medium level (web)developers (RJS
Templates, Migrations, Polymorphic associations), your 1st edition
cover unchanged basics for beginning, let''s go :)

I''m using last Rails 1.1.4 with 1st, just printed some chapters from
2nd PDF (Migrations) because I want use them, and I keep an eye on the
online API for new methods and minor changes.
>What about "Rails Receipes" as well?
Good indeep rails programming techniques, a very good complement, and
more up to date with rails 1.1 than AWDWR, too few RJS for my taste.

Yeah, I started to teach myself Rails a week ago with the first edition
book, but found that certain aspects were a little behind the kind of code I
was seeing in online tutorials, etc. (especially with regards to database
migration, if you watch the "migrations" screencast you''ll be
scratching
your head with the first ed.)...so I picked up the beta .pdf of the second
edition, and am liking it much more.  Just in the depot application, some
things are implemented in a much cleaner way (more "Ruby-like" seems
to be
the parlance).

On the other hand, if you can''t wait to start coding, you can use the
first
edition for now, just check out a tutorial on migrations:

http://glu.ttono.us/articles/2005/10/27/the-joy-of-migrations

and use those instead of the DDL schemas used in the book.  That seems to be
the most important difference with regards to the example app (other than
the second ed. gives some examples of AJAX integration).  As for the rest of
the book, I haven''t gotten there yet :-)

I would still strongly recommend getting the second edition book when it
comes out (or getting the beta .pdf now.)  I seem to recall that the thing
is scheduled for release in September, so it''s not much of a wait.

--Louis

On 8/9/06, James Ludlow <jamesludlow@gmail.com>
wrote:
>
> On 8/9/06, Rob Gabaree <lists@rawb.net> wrote:
> > I purchased the first edition of "Agile Web Development with
Rails" some
> > time back and never had a time to get into it.  I want to learn now
but
> > I''ve seen there''s a second edition.  Is the content
in the first edition
> > still relevant, or are some parts of it "depreceated" or no
longer
> > current?  Should I get the second edition?  What about "Rails
Receipes"
> > as well?
>
> I have the 1st edition and I don''t regret buying the 2nd edition
at
> all.  It''s been well worth it, even as a beta book.
>
> Pieces of the 1st edition are deprecated, yes.
>
> -- James
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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On Wednesday, August 09, 2006, at 5:23 PM, Mathieu Chappuis
wrote:
>> I purchased the first edition of "Agile Web Development with
Rails" some
>> time back and never had a time to get into it.  I want to learn now but
>> I''ve seen there''s a second edition.  Is the content
in the first edition
>> still relevant, or are some parts of it "depreceated" or no
longer
>> current?  Should I get the second edition?
>
>AFIK there are no statements in 1st deprecrated with Rails 1.1.4.
>
>Sure, 2nd edition have majors rewrite and additions, but you can start
>learning with a recent rails setup and this book.
>
>Big enhancements in 2nd are for medium level (web)developers (RJS
>Templates, Migrations, Polymorphic associations), your 1st edition
>cover unchanged basics for beginning, let''s go :)
>
>I''m using last Rails 1.1.4 with 1st, just printed some chapters
from
>2nd PDF (Migrations) because I want use them, and I keep an eye on the
>online API for new methods and minor changes.
>
>>What about "Rails Receipes" as well?
>
>Good indeep rails programming techniques, a very good complement, and
>more up to date with rails 1.1 than AWDWR, too few RJS for my taste.
>_______________________________________________
>Rails mailing list
>Rails@lists.rubyonrails.org
>http://lists.rubyonrails.org/mailman/listinfo/rails
A lot of the testing stuff in the 1st edition is deprecated now.   
Especially the stuff related to instantiated fixtures.

_Kevin
www.sciwerks.com

-- 
Posted with http://DevLists.com.  Sign up and save your mailbox.

I found the Recipes book to be very good depending on your Ruby
skillz.  If you Ruby skillz needs some love David Black''s "Ruby
for
Rails" is really good.  But I have 2nd edition of the Agile book in
beta and I felt it was a worthy upgrade over the 1st edition.



On 8/9/06, Richard Conroy <richard.conroy@gmail.com>
wrote:
> Rails Recipes is quite good too, but it is very much advanced
> material for people comfortable with Rails. n00bs like me can''t
> put much of it into practice, but theres a lot of nice stuff in there
> - kind of a reward at the end of the journey.
>
> On 8/9/06, James Ludlow <jamesludlow@gmail.com> wrote:
> > On 8/9/06, Rob Gabaree <lists@rawb.net> wrote:
> > > I purchased the first edition of "Agile Web Development with
Rails" some
> > > time back and never had a time to get into it.  I want to learn
now but
> > > I''ve seen there''s a second edition.  Is the
content in the first edition
> > > still relevant, or are some parts of it "depreceated"
or no longer
> > > current?  Should I get the second edition?  What about
"Rails Receipes"
> > > as well?
> >
> > I have the 1st edition and I don''t regret buying the 2nd
edition at
> > all.  It''s been well worth it, even as a beta book.
> >
> > Pieces of the 1st edition are deprecated, yes.
> >
> > -- James
> > _______________________________________________
> > Rails mailing list
> > Rails@lists.rubyonrails.org
> > http://lists.rubyonrails.org/mailman/listinfo/rails
> >
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

-- 

Just because you ''re not paranoid doesn''t
mean they aren''t out to get you.

On Aug 9, 2006, at 13:25, Kevin Olbrich wrote:
> A lot of the testing stuff in the 1st edition is deprecated now.
> Especially the stuff related to instantiated fixtures.

That''s the biggest problem--they made that incompatible change after  
the book went to press. The other stuff should work, but the new  
Rails adds a lot of additional features (such as migrations and RJS)  
they are pretty important.

The first edition still works in terms of writing viable code for  
Rails applications...


Dave
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