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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Hello,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">I would like to use the value of a field/attribute in a parent table as a filter in an expression used to display features in the child table.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Specifically, I have a 1:n relationship (composite) saved in my project:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Sectors
</span></b><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">(<b><i>parent</i></b> table with polygon geometry, a key "FID" and a field/attribute "TYPE")<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Trees</span></b><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"> (<b><i>child</i></b> table with point geometry, and a secondary key "SECTORS_ID")<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="DE-CH" style="font-size:10.0pt;font-family:"Open Sans",sans-serif">I would like to use this relationship in the rule-based symbology renderer so that, for example:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="DE-CH" style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Trees whose parent Sectors have "TYPE" = 'Project'</span></i><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"> are displayed as a blue circle<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Trees whose parent Sectors have "TYPE" = 'Parking'</span></i><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"> are displayed as a red circle<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">My questions:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Using the relate, how do I build my expression in the rule-based renderer so that I can differentiate between Trees related to a Sector of a specific type?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Should I look for a way to use « @parent » in the child table, along with the get_feature() and/or attribute() function ?
</span><span lang="DE-CH" style="font-size:10.0pt;font-family:"Open Sans",sans-serif">I understand the @parent parameter is only used for the aggregate() function.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="DE-CH" style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">The expression should make use of the relate, using the value of the parent attribute "TYPE" ; also, the condition is not always spatial thus refFunction plugin is not being
used. The point is also not to use a view.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">I'd rather avoid the following, but as an alternative: how would I create a virtual field "SECTOR_TYPE" in my child table that would be filled with the value of the "TYPE"
field located in the corresponding parent feature?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">I am using QGIS 3.10.1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="DE-CH" style="font-size:10.0pt;font-family:"Open Sans",sans-serif">Thanks in advance for your help.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="DE-CH" style="font-size:10.0pt;font-family:"Open Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif">CJ</span><span style="font-size:10.0pt;font-family:"Open Sans",sans-serif;color:black;mso-fareast-language:FR-CH"><o:p></o:p></span></p>
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