Re: [BABEL] ob-rec.el and some questions

From: "Eric Schulte" <schulte.eric@gmail.com>
To: "Jose E. Marchesi" <jemarch@gnu.org>
Cc: emacs-orgmode@gnu.org
Subject: Re: [BABEL] ob-rec.el and some questions
Date: Tue, 15 Feb 2011 11:35:15 -0700	[thread overview]
Message-ID: <87sjvp5dzr.fsf@gmail.com> (raw)
In-Reply-To: 877hd2uxym.fsf@gnu.org

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jemarch@gnu.org (Jose E. Marchesi) writes:

> Hi.
>
> I have been playing a bit with org babel, the goal being to be able to
> query a recfile[1] and insert the result as a rec table.  Thanks to the
> superb design of org-babel and the existing examples, I quickly wrote
> the attached little hack.
>
> The hack allows to query a rec file 'foo.rec' as follows:
>
> #+begin_src rec :data hackers.rec :fields Name,Email :type Hacker
> Papers = 'requested' && CreatedAt << '01 January 2011'
> #+end_src
>

Very cool!  Now is the time when I ask, would you consider adding this
to the Org-mode core, which requires filling out the FSF copyright
assignment form?  http://orgmode.org/worg/org-contribute.html#sec-2

>
> Where :data points to the recfile (or list of files), :fields is a
> comma-separated list of fields (allowing subscripts) and :type selects
> the record set where to make the query. :cmdline can also be used to
> specify any other command line option to recsel.  All parameters but
> :data are optional.
>
> The selection expression can be any expression allowed by recsel in the
> -e command line option.
>
> Of course you have to install the recutils for it to work.
>
> It roughly works and I want to add more functionality, but due to my
> lack of experience with org-babel I would like to ask some questions
> before continuing working on it.
>
> - Is there a way to execute empty code blocks?  It would be quite common
>   to require all the records stored in a record set, e.g.
>
>   #+begin_src rec :data inventory.rec
>   #+end_src
>
>   C-cC-c in that block echoes "Local setup has been refreshed" and
>   nothing happens.  A workaround would be to use a selection expression
>   that always evaluates to "true", such as:
>

With my attached version of ob-rec.el it is possible to have a mostly
empty body as follows, however, currently `org-babel-get-src-block-info'
*does* require that there be at least 1 character as well as a newline
in the body.  This could be changed, however I'd want to do some local
testing before pushing up such a change, as I fear it may break existing
code blocks.

#+begin_src rec :data book.rec :fields Title,Author

#+end_src

#+results:
| Title...
| GNU Emacs Manual...

>
>   #+begin_src rec :data inventory.rec
>   1
>   #+end_src
>
>   but it would be nice to avoid it.
>
> - Is there a way to dinamically change the value of the :results
>   parameter in the org-babel-execute:rec function?  I would like to add
>   a :template parameter containing a template for recfmt, and in that
>   case the default value "raw" would not be appropriate.
>

Please see my attached revision of ob-rec.el.  I do not believe that the
default value of raw is appropriate currently as Babel should know when
the returned results are a table.  I've slightly modified your existing
code so that raw is no longer the default value, and so that tables are
passed back as tables.  Does this change subsume your format question?

>

Also, it sounds like there is currently only support for selecting
records *from* a .rec file, do you plan on adding support for inserting
records *into* a .rec file?

Thanks for sharing! -- Eric

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>
> Thanks in advance :)
>
> [1] http://www.gnu.org/software/recutils

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