On 30 March 2015 at 23:07, Junior Delaz <del...@gmail.com> wrote: > > Hi, > Niccolo, Nathan is right. his proposal is the simplier and recommanded. > But I think your formulae should work if you write > $atlasfeatureid || '_' || attribute($atlasfeature, 'name' ). > Only simple quote ' and not " near the field's name inside attribute function > brackets. > > By the way, can someone explain me why for some functions (attribute, > getFeature), you need to use simple quote for the fields and double quotes > when using other functions ? > And when you double-click on field's name, they are always appended to your > expression with double quote. Can this be standardised ? >
Double quotes will give you the value of that field. It's standard behaviour. But when you write: attribute($atlasfeature, "name" ) you're actually saying "fetch the value of the attribute named 'name', and then get the attribute from $atlasfeature which is called that value". Eg, if your feature's 'name' field has a value "New York", then the expression will be retrieving the value of the "new york" attribute from $atlasfeature. Most likely your feature doesn't have an attribute called "New York", so nothing is returned. The single quote is a literal. So: attribute($atlasfeature, 'name' ) means "fetch the attribute from $atlasfeature which is called 'name'". So this would return "New York". Hope that helps clarify! Nyall _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
