[Qgis-user] Layer driven Atlas
Neumann, Andreas
a.neumann at carto.net
Wed Mar 2 06:36:25 PST 2016
Thomas,
The other thing when you use virtual layers: did you introduce a unique
column that can be used as primary key, enabled and entered a "Unique
identifier column"?
Otherwise I wouldn't be surprised that @atlas_featureid doesn't work.
Andreas
On 2016-03-02 14:58, Neumann, Andreas wrote:
> Hi Tom,
>
> @atlas_feature returns a full feature - with geometry and attributes - similar to a full database record type. With this feature you could extract the geometry and the attributes.
>
> You probably want @atlas_featurenumber and @atlas_totalfeatures ?
>
> @atlas_featureid should return the unique id (primary key) of your feature. I just tested it with a physical table and it worked. If it doesn't work, it may well be a side-effect of using a virtual layer? If this is the case - could you try saving the virtual layer to a physical table?
>
> Greetings,
>
> Andreas
>
> On 2016-03-02 14:33, Thomas Colley wrote:
>
> Hi Andreas
>
> That's excellent, thanks so much, I never thought about joining tables. The virtual layer works really well.
>
> Again I'm not sure if I'm doing something wrong or a bug but some of the atlas variables aren't working as expected:
>
> atlas_feature and atlas_featureid return <feature: 0> and 0 respectively no matter which atlas page you're on. atlas_featurenumber, atlas_filename, atlas_pagename all work as they should.
>
> I have got round this by using atlas_pagename (set using the name attribute) in the data defined layer settings (I had been trying attribute( @atlas_feature , 'name')).
>
> Cheers
>
> Tom
>
> FROM: Qgis-user [mailto:qgis-user-bounces at lists.osgeo.org] ON BEHALF OF Andreas Neumann
> SENT: 01 March 2016 20:12
> TO: qgis-user at lists.osgeo.org
> SUBJECT: Re: [Qgis-user] Layer driven Atlas
>
> Hi Thomas,
>
> You will need a table with a record per page for the atlas coverage layer.
>
> So if, f.e. you have a table with administrative units (with geometries) and a table with temporal layers (e.g. an ortho-image every 5 years or so) you will need to do a cross-join between the two tables.
>
> See http://www.tutorialspoint.com/sqlite/sqlite_using_joins.htm
>
> You can use the new Virtual layer feature from QGIS 2.14 to create such a layer on-the-fly without having to store a separate layer. Let us know if you need help on the virtual layer.
>
> Hope this helps,
> Andreas
>
> On 01.03.2016 16:58, Thomas Colley wrote:
>
> Hi everyone
>
> I was just looking through the changelogs and got really excited when I saw data defined control over map layers! (http://www.qgis.org/en/site/forusers/visualchangelog212/index.html#feature-data-defined-control-over-map-layers-and-style-presets)
>
> This is exactly what I'd been asking about on the list last year (http://lists.osgeo.org/pipermail/qgis-user/2015-August/033211.html) so thanks so much to Nyall for adding this functionality!
>
> I'm not 100% sure that I'm using it in the correct way though. I have managed to achieve it by duplicating my atlas coverage features so that there is one feature per layer with an attribute holding the layer name. I then use the attribute in the data defined layers option.
>
> Is this the way to do it or am I missing something? I wasn't sure where/if the 'set layer list from a visibility preset' should come into play.
>
> When I first read the post I thought that the | separated list of layers would be cycled through one by one but then realised that they'd all be displayed together.
>
> I have a static list of 20 or so layers to cycle through for each site so ideally if I could specify a list of layers (or visibility presets) to loop through that would be amazing.
>
> Failing that I can write a little plugin to take a selected feature and create a scratch layer with the feature duplicated with the layer attribute values.
>
> Thanks again for adding this, it'll be a massive time saver for us!
>
> Tom
>
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