[Qgis-developer] New feature: RFC saving style and ui in Spatialite

[Gino Pirelli]

regarding how to implement saving SLD in spatialite i downgraded my
previous using simple text field... avoiding blob or XmlBlob (SL>4.1)

the reason is to allow more simpler interoparability reading back sld.
Using directly text I can read it's value directly. values are utf8
enconded and reading them outside qgis context (I received some comments
about this) it's simple to understand that text value has a locale coding.

- I decided to avoid sqlite blob because of to simplify interoperability
avoiding blob decoding step that it's less uman "natural"
- I decided to avoid XmlBlob format because it's available only with SL >
4.1. I plan to use this data type when SL 4.1 will be more used. At the
moment I preferred to allow this functionality available in all platform
and distribution in witch  qgis is available and in some of them (e.g.
debian wheezy, Ubuntu 13) SL 4.1 it's not packaged.
- I hope to add the same functions to the the new GeoPackage, but this it's
not still planned.

please let me know if there are comments

code is here:
https://github.com/luipir/QGIS/tree/spatialite-savestyle

diff is here:
https://github.com/luipir/QGIS/compare/spatialite-savestyle

thank you,

Luigi Pirelli (luigi.pirelli at faunalia.it - luipir at gmail.com)


On 5 February 2014 13:18, Gino Pirelli <luipir at gmail.com> wrote:

> Hi,
>
> I'm developing a new feature to save SLD and ui in Spatialite provider in
> the same way this function is available for postgres.
>
> this function developed for Faunalia is funded by ARPA Piemonte
> fork is available at:
> https://github.com/luipir/QGIS/tree/spatialite-savestyle
> and actual modification are localized in this
> commit: f058bea1fe51116b8231eb5c1ca4faee485c38b2
>
> there are some question about how to develop it and are related how to
> manage XML in a sqlite/spatialite table.
>
> this code derive by the postgres provider code where QML and UI xmls are
> recorded in a XML column. XML is a postgres type. This type is not
> available in SQlite but it's available in SL 4.1> (called XmlBlob [1])
> In this preliminary commit XML is saved in a text column, but saving XML
> as a blog (blob type in sqlite or XmlBlob in SL) have the advantage to
> avoid all encoding problems.
>
> so the question is... sqlite blob or spatialite xmlbob?
>
> Blob type can't allow XML parsing using SQL queries
> XmlBlob allows this (using libxml2)
>
> Blob type is sqlite native type
> XmlBlob can be used only with SL 4.1>
>
> My preference is to use native data type Blob. What's you opinion about
> blob/ xmlblob or whatever
>
> regards,
>
> Luigi Pirelli (luigi.pirelli at faunalia.it - luipir at gmail.com)
>
> [1] https://www.gaia-gis.it/fossil/libspatialite/wiki?name=XmlBlob-intro
>
>
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