[Qgis-user] troubles with QGis Atlas

[Nyall Dawson]

On 12 January 2016 at 12:01, Nyall Dawson <nyall.dawson at gmail.com> wrote:
>
> On 12 Jan 2016 8:36 AM, "didier peeters" <dpeeter1 at ulb.ac.be> wrote:
>>
>> Thank you Nyall.
>>
>> Oh, this could be the reason.  To clarify a little bit, my field is not
>> called « id » and my coverage layer is a Postgis table, the field I use has
>> a PK and the geometry layer is a Postgis view with numerical values that I
>> represent with proportional circles.
>> Does it mean that what I want to do is not possible ?  Or should I use
>> another data source ?
>
> It should be possible. Can you share a few rows from both tables?
>

(sharing the solution with the list)

After looking at your data, the ID field in your database is a string.
Feature IDs in QGIS are always numeric, so QGIS generates it's own
feature ID and can't reuse the database's primary key.

The solution is to update your expression. Instead of "id_field" =
@atlas_featureid'

Use

 "id_field"  = attribute( @atlas_feature,'id_field' )

Nyall



> Nyall
>
>>
>> Didier
>>
>>
>> > Le 11 janv. 2016 à 21:26, Nyall Dawson <nyall.dawson at gmail.com> a écrit
>> > :
>> >
>> > On 12 January 2016 at 02:18, didier peeters <dpeeter1 at ulb.ac.be> wrote:
>> >> Hello,
>> >>
>> >> I’ve started to use the Atlas in QGis composer: I use a non-geometry
>> >> table
>> >> as coverage layer, providing the feature id’s and corresponding labels
>> >> for
>> >> my maps, and I display always the same extent but with different data
>> >> of
>> >> course, using a rule-based style like ‘ "field" = @atlas_featureid'.
>> >> At
>> >> first it worked fine but now, the atlas mistakes @atlas_featurenumber
>> >> for
>> >> @atlas_featureid, i.e. instead of displaying the data corresponding to
>> >> the
>> >> feature id it displays the data corresponding to the number of the
>> >> feature
>> >> (~ the row number, as some are filtered out), but selects properly the
>> >> labels corresponding to the feature value.  So I obtain maps with a
>> >> title
>> >> which is not related to the content !
>> >> In the expression editor @atlas_featureid and @atlas_featurenumber are
>> >> previewed with the same Current value although they are different !
>> >>
>> >> Does anyone have an idea about this ?
>> >
>> > Keep in mind that feature id's might not be predictable, depending on
>> > your data source. They aren't user visible, and as such aren't
>> > suitable for a join like this.
>> >
>> > Did you mean instead to use a field called "id" from your coverage
>> > layer?
>> >
>> > Nyall
>> >
>> >>
>> >> I use QGis 2.12.1 on Mac.
>> >>
>> >> Didier
>> >>
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