[Georuby-devel] post_gis_adapter's to_yaml function

Guilhem Vellut guilhem.vellut at gmail.com
Wed May 31 03:55:38 EDT 2006

Well actually, it does not work totally fine when trying to manually input a
geometry in a fixture (with something like <%=
Point.from_x_y(123.4,567.1).to_yaml %>), using the default  "to_yaml" for
objects of the YAML library. The problems are that the document separator
("---") is output and that the components of the Point are not indented,
which makes the YAML parser crash when reading the fixture. Do you know of
options to prevent that? 


Therefore for now I will keep the former to_yaml methods specific to
geometries and rename them "to_fixture_format", so the dumping to YAML
format can work, as well as the input of geometries in a fixture.





From: Doug Cole [mailto:dougcole at gmail.com] 
Sent: 31 May 2006 11:00
To: georuby-devel at rubyforge.org
Cc: Guilhem Vellut
Subject: Re: [Georuby-devel] post_gis_adapter's to_yaml function


Sorry, I should have been more specific.  The code I was looking at that has
reference to the optional hash array was the yaml code in the ruby standard
library, where to_yaml is defined for the built in classes
(yaml/rubytypes.rb)  Here's a reference to the options hash:
http://yaml4r.sourceforge.net/doc/page/the_options_hash.htm.  I was trying
to use the spatial adapter's to_yaml to dump part of my database to a yaml
file, with the ar_fixtures plugin (
) basically the call boils down to converting an activeRecord's attributes
to yaml ( row.attributes.to_yaml).  Like I said, simply removing the to_yaml
function from the postgis_adapter fixed it for me, as yaml defaults to
simply outputting all the instance variables, which works fine in my case.

-On a related note - I was reading the archives for this mailing list and
saw that someone was trying to figure out how to get a Geometry column into
their fixture.  This is probably too late to help here, but Fixtures are run
through the same interpreter as .rhtml files are so you can always do
something along the lines of #{ Point.from_x_y(x, y).to_yaml} if you're not
sure...hope that helps.

On 5/30/06, Guilhem Vellut <guilhem.vellut at gmail.com > wrote:

Hello Doug,


I don't have all the elements to solve your problem. When you write "looking
through the yaml code it looks like there's an optional options hash", what
yaml code are you referring to? And how are you trying to use the method?


If you use it in fixtures, the to_yaml method for geometries is used the
following way:


  id: 1


  value: 3

geom: <%= Geometry.from_ewkt('POINT(1.4 5.67)').to_yaml %>

And it outputs the canonical representation of the geometry for the target
database (HexEWKB for PostGIS).






From: georuby-devel-bounces at rubyforge.org [mailto:
<mailto:georuby-devel-bounces at rubyforge.org>
georuby-devel-bounces at rubyforge.org] On Behalf Of Doug Cole
Sent: 31 May 2006 03:26
To: georuby-devel at rubyforge.org
Subject: [Georuby-devel] post_gis_adapter's to_yaml function


  I just tried to use the to_yaml function in the post_gis_adapter and ran
across some problems:

-first I got an error related to the number of arguments (1 for 0), looking
through the yaml code it looks like there's an optional options hash so I
simply redefined the function as  "to_yaml( opts = {} )"  

-after fixing that I recieved the error "wrong argument type String
(expected Data) (TypeError)" which I haven't tackled.

anyone else run into these problems?  I was trying to dump some point data
from my postgres database to a fixture for testing.  Simply removing the
to_yaml definition fixed things, so that's how I've left it, but I thought
I'd report the problem. 


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