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<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">Hi developers.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">I asked this question on the user’s list, so far without any answers, but have been advised to ask here as well.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">I’m working with a number of projects, which statically open a fixed number of layers. All layers are fetched using WFS / WFS-T.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">Each layer has an extensive rule based styling, and an extensive field/attribute dialog setup. This is saved in the project files.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">Our plugin changes the data provider filter for many layers, when the user works with the data. These filter expressions are also saved in the project, of course.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">Our problem is, that if the user accidently chooses a work area (= new data provider filter), which contain no data in any layer, those layers lose all styling
etc. And it’s apparently impossible to recover these styles etc. by changing the filter back.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">So basically the user’s project is unrecoverably trashed at this point in time.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">A - Is this a correct description of how QGIS handles “no-data” layers ?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">B - Are there any standard ways to handle this in QGIS (using metadata or otherwise) in an automated fashion (i.e. not manually) ?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">C - If the answers to A and B are yes and no resp., are there any plans to remedy this unnecessarily serious problem ?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">Might it not be solved simply by adding an (optional?) layer metadata key, that stores the last used topology, and revert to this if no data are found on the layer
?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">Using 3.4.5 x64 (Danish)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Med venlig hilsen</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:11.9pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Lars I. Nielsen, LIFA A/S</span><span style="font-family:"Arial","sans-serif""><br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial","sans-serif"">GIS-konsulent, FME Certified Professional</span><span style="font-family:"Arial","sans-serif""><br>
<br>
</span><span style="font-size:8.0pt;font-family:"Arial","sans-serif";color:black;mso-fareast-language:DA"><img width="270" height="77" id="_x0000_i1026" src="cid:image001.gif@01D5066B.0B3D9430" alt="Beskrivelse: http://website.lifa.dk/lsp.gif"></span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:red">T</span></b><o:p></o:p></p>
</td>
<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">6313 6800</span><o:p></o:p></p>
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<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:red">@</span></b><span style="font-size:10.0pt;font-family:"Arial","sans-serif""> </span><o:p></o:p></p>
</td>
<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">lin@lifa.dk</span><o:p></o:p></p>
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<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:red">D</span></b><o:p></o:p></p>
</td>
<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">6313 6849</span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:red">W</span></b><o:p></o:p></p>
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<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif""><a href="http://www.lifa.dk"><span style="color:blue">www.lifa.dk</span></a></span><o:p></o:p></p>
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<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:red">M</span></b><o:p></o:p></p>
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<td style="padding:0cm 0cm 0cm 0cm">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">2492 4866</span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:red">CVR</span></b><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">20937289</span><o:p></o:p></p>
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<p class="MsoNormal"><br>
<a href="https://www.linkedin.com/company/lifa-a-s/"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue;mso-fareast-language:DA;text-decoration:none"><img border="0" width="21" height="21" id="_x0000_i1025" src="cid:image002.png@01D5066B.0B3D9430" alt="Beskrivelse: C:\Users\lin\AppData\Roaming\Microsoft\signatures\21x21-Images-Get-L749-l8.png"></span></a><span style="font-size:10.0pt;font-family:"Arial","sans-serif""><br>
Følg os på LinkedIn og læs de seneste nyheder fra LIFA A/S </span><o:p></o:p></p>
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