How to add a new Active Layer

When you have a layer that you want to be able to graphically select from and report on its attributes, it needs to be set up as an Active Layer. This article assumes that you already have some Active Layers configured in Weave. 

** IN PROGRESS **

Step-by-step guide

1. If the layer you want to add as a new Active Layer is in the Table of Contents (TOC)/Map Layers, make a note of the name shown in the TOC.
   1. • Generally, an Active Layer is related to a Map Layer from the TOC but it doesn't have to be as the case. In the extreme, you can have only a raster base map in your TOC but you will still be able to do a graphical selection and have the selection appear over the raster map. In this case it will appear as though features on the raster map have been selected, while in fact it is the vector layer that is used in the graphical selection.
2. Open your toc.xml file for editing. Search for the name of the Map Layer you identified above (it will appear as the label tag). Note the value of the layer parameter.

3. While you're in the toc.xml, add a XML Attribute called entity.
   
   In the example below the entity attribute is added to the counciltrees layer and is set to counciltrees and is specified as:

   <entry id='l_mapengine.main_counciltrees' layer='counciltrees' label='Council Trees' checked='false' entity='counciltrees'/>
   

   Adding this entity attribute sets the relationship between the Active Layer and the Map Layer that is drawn from the TOC and means the Map Layer in the TOC will be highlighted when the corresponding layer is selected from the Active Layer list. To have the Set Active option available on the TOC Context Menu (right mouse click), ensure you have the weave.toc.selectLayer item enabled in the client_main.xml file.
   
   
   
   
   

4. Open your entity.xml file for editing. Add an XML Element for this entity. 

   <entity:entity id='counciltrees'>
        <label>Council Trees</label>
   </entity:entity>

   
   The value of the (XML Attribute) id  for the entity (shown in the image above) should match the (XML Attribute) entity from the toc.xml file (shown in Step 3). In our example it's "counciltrees". 
   
   The label in the entity.xml doesn’t have to match the label in the toc.xml file but it’s recommended to keep them the same to avoid confusion for the user, unless there’s a good reason why these should be different.
   
   

5. If you refresh your browser you'll now see the Active Layer has been added to the Active Layer drop-down list. However it will have a different icon to the other Active Layers in the list as it hasn't been linked to a spatial database. 
   
   
    

6. Stay in the entity.xml file. You now need to specify where the spatial data for the selection will be coming from by adding another mapping XML Entity that links the Active Layer to its relevant Spatial Engine. Add this to the mapper element that is reading from the required Spatial Engine,and include the table name, key field, etc. as shown below. You can set a filter tag so that only features that meet certain criteria will be considered for selection.
   
   

   <mapping>
   	<entity>counciltrees</entity>
   	<spatialengine>postgis</spatialengine>
   	<table>counciltrees</table>
   	<key>ogc_fid</key>
   	<dynamic>true</dynamic>
   </mapping>

   
   If there are no Active Layers from the Spatial Engine you need to access, then you'll need to add a new tag for that Spatial Engine. For simplicity, give this mapper an id of mapper.<spatialengine_id> as shown below. 
   
   

   <mapper:mapper id="mapper.postgis">
   	<mapping>
   		<entity>counciltrees</entity>
   		<spatialengine>postgis</spatialengine>
   		<table>counciltrees</table>
   		<key>ogc_fid</key>
   		<dynamic>true</dynamic>
   	</mapping>
   </mapper:mapper>

   
   If you refresh your browser you'll now see that the icon for that Active Layer has changed to a layer-like icon.This icon indicates that the Active Layer is now a spatial layer.

   
   
   

7. If you now run a spatial selection, the selected features will be highlighted in the Map Window. The number of features selected will be reported in the bottom right of the Weave window, in the Status Bar, as “Selection Size”.
8. You may need to refresh your browser to see this attribute appear in your Data Grid window. 
   

    

9. Done.

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