[Qgis-user] Postgres arrays in QGIS and form widget

[Matthias Kuhn]

Hi Olivier,

There is some support for this in the value relation widget. If you
allow multiple selections, it will make use of the array notation,
storing multiple foreign keys ( { fk1, fk2, fk3 } ).

If you want to get further support for this, you could write your own
form elements which is possible for some time (although I haven't seen
it widely used).
http://blog.vitu.ch/10142013-1847/write-your-own-qgis-form-elements

For your last use-case "same number of items" you should consider to
normalize your database and and have two tables linked with a foreign key.

CREATE TABLE lots(
  id serial,
  common_data text
)

CREATE TABLE person(
  id serial,
 first_names text,
 last_names text,
 age int,
 group integer REFERENCES lots(id)
)

Matthias

On 01/11/2015 03:17 PM, Olivier Dalang wrote:
> Hi !
>
> Postgres' arrays are a great feature. They allow store several values
> in one field :
>
> CREATE TABLE lots(
>     id serial,
>     owners text[]
> );
> INSERT INTO lots(owners) VALUES( ARRAY['john','mike','jenny'] );
>
> But is there a way to edit this cleanly in QGIS with the forms ?
> Natively, the form widget will be a plain text input, and the value
> will display like this
> {"john","mike","jenny"}
> This is more or less usable for text fields, but not really clean,
> since the user needs to escape some characters, and it's not very
> readable. But then it's impossible to use with other widgets
> (checkbox, range, etc.)
>
> I'd love to have a dynamic input where the user could add and remove
> fields, and where QGIS widget types could be used.
>
> Actually, I'd even need a form where I'd have the same number of items
> for several arrays, and where adding/removing an item would work on
> several field at once, to work on a table like this :
> CREATE TABLE lots(
>     id serial,
>     first_names text[],
>     last_names text[],
>     age int[]
> );
>
>
> Is there a way to do it ?
> Maybe with python ?
> Has anyone of you already done this and would agree to share ?
> Any pointer in the right direction would be very welcome !
>
> Thanks a lot in advance,
>
>
> Olivier
>
>
>
>
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