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PUBLIC<br>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">Hello,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">I am having issues getting relate_aggregate to do anything within expression builder. Ideally, I would like a features (1) to (m) attributes table setup correctly with
a relationship to allow a user to select attributes based on attribute criteria have the corresponding related features selected / shown on map as related. Given how little I am uncovering online about ways to do this, it might not be possible, but even getting
the expression builder to update a field in my features with a count of corresponding values in attributes is not updating feature’s values, I am wondering if I am doing something wrong. Should this work? <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">Within select by attributes for the feature table:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">relation_aggregate( 'relation _ID','count',1) > 3<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">The preview of the expression returns a value for a feature (without the >3 at end), but when I try to calculate a field of this count – every value returns NULL. With
the >3 it does not work at all to select anything.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">It does look like ‘relation_aggregate( 'relation _ID','count',1)’ is fine for the basis of evaluating a field of values based on preview but it returns null on running
the field calculator.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">I am using QGIS 3.16<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#3B3838;mso-fareast-language:EN-GB">Graeme</span><o:p></o:p></p>
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