Handle Attribute Names containing Dot Notation in Identify Templates

[tchaddad]

Stumbled on a case of a federal service that is returning features where the attribute names contain the parent table name using dot notation. This makes it difficult (currently impossible?) to set up an identify template in a map source because the expected format in the template is:

{{ properties.ATTRIBUTE }}

But the actual attribute names in the returned reqwest object are in this format:

"TableName.ATTRIBUTE"

Using <template name="identify" auto="true"/> will dump out all the available attributes as-is without a failure, but attempting to specify particular attributes in a custom identify template doesn't seem possible due to the dot notation.

This example map source to the live service should drop directly into the main GM demo:

	<map-source name="usfws-nwi" opacity="0.6" type="ags" >
		<url>
		https://fwsprimary.wim.usgs.gov/server/rest/services/Test/Wetlands_gdb_split/MapServer/export
		</url>
		<param name="cross-origin" value="anonymous"/>
			<layer name="Wetlands_CONUS_East" query-as="usfws-nwi-query/Wetlands_CONUS_East">
				<param name="layers" value="show:1"/> 
				<param name="FORMAT" value="image/png;bits=8"/>		
			</layer>
	</map-source>
	
	<map-source name="usfws-nwi-query" type="ags-vector">
		<url>
		https://fwsprimary.wim.usgs.gov/server/rest/services/Test/Wetlands_gdb_split/MapServer/1
		</url>
		<config name="pixel-tolerance" value="1"/>
		<param name="cross-origin" value="anonymous"/>
		<layer name="Wetlands_CONUS_East" title="NWI Wetlands">
				<template name="identify" auto="true"/>
				<!--  
				<template name="identify" ><![CDATA[
					<div > 
						<div  style="background-color: #7ABF6B; padding: 6px;"> 
							National Wetlands Inventory
						</div>
						<div style="padding: 2px;">	<b>Attribute: </b>{{ properties.Wetlands_CONUS_East.ATTRIBUTE}} </div>
					</div>  
					]]>				
				</template> 
				-->
		</layer>
	</map-source> 
	

Catalog snippet:
<layer title="National Wetland Inventory" src="usfws-nwi/Wetlands_CONUS_East" status="off" metadata="true" legend="false" fade="false" unfade="false">

Doing an identify on this layer should show the issue. The second template that is included but commented out would be an example of identifying just one field, which fails due to the field name format.

[klassenjs]

Example Feature:

{
  "type": "Feature",
  "geometry": {
    "type": "Polygon",
    "coordinates": [
      [
       
      ]
    ]
  },
  "properties": {
    "Wetlands_CONUS_East.OBJECTID": 14029175,
    "Wetlands_CONUS_East.ATTRIBUTE": "PFO4D",
    "Wetlands_CONUS_East.WETLAND_TYPE": "Freshwater Forested/Shrub Wetland",
    "Wetlands_CONUS_East.ACRES": 491.61428823978684,
    "Wetlands_CONUS_East.GLOBALID": "{311CFBC9-707D-4CBA-8A26-96C712364BD4}",
    "Wetlands_CONUS_East.Shape_Length": 19250.87502049433,
    "Wetlands_CONUS_East.Shape_Area": 4122290.5997585068,
    "NWI_Wetland_Codes.OBJECTID": 3460,
    "NWI_Wetland_Codes.ATTRIBUTE": "PFO4D",
    "NWI_Wetland_Codes.SYSTEM": "P",
    "NWI_Wetland_Codes.SYSTEM_NAME": "Palustrine",
    "NWI_Wetland_Codes.SYSTEM_DEFINITION": "The Palustrine System includes all nontidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or lichens, and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5 ppt. It also includes wetlands lacking such vegetation, but with all of the following four characteristics: (1) area less than 8 ha (20 acres); (2) active wave-formed or bedrock shoreline features lacking; (3) water depth in the deepest part of basin less than 2.5 m (8.2 ft) at low water; and (4) salinity due to ocean-derived salts less than 0.5 ppt.",
    "NWI_Wetland_Codes.SUBSYSTEM": null,
    "NWI_Wetland_Codes.SUBSYSTEM_NAME": null,
    "NWI_Wetland_Codes.SUBSYSTEM_DEFINITION": null,
    "NWI_Wetland_Codes.CLASS": "FO",
    "NWI_Wetland_Codes.CLASS_NAME": "Forested",
    "NWI_Wetland_Codes.CLASS_DEFINITION": "Characterized by woody vegetation that is 6 m tall or taller.",
    "NWI_Wetland_Codes.SUBCLASS": "4",
    "NWI_Wetland_Codes.SUBCLASS_NAME": "Needle-Leaved Evergreen",
    "NWI_Wetland_Codes.SUBCLASS_DEFINITION": "The dominant species in Needle-leaved Evergreen wetlands are young or stunted trees such as black spruce or pond pine.",
    "NWI_Wetland_Codes.SPLIT_CLASS": null,
    "NWI_Wetland_Codes.SPLIT_CLASS_NAME": null,
    "NWI_Wetland_Codes.SPLIT_CLASS_DEFINITION": null,
    "NWI_Wetland_Codes.SPLIT_SUBCLASS": null,
    "NWI_Wetland_Codes.SPLIT_SUBCLASS_NAME": null,
    "NWI_Wetland_Codes.SPLIT_SUBCLASS_DEFINITION": null,
    "NWI_Wetland_Codes.WATER_REGIME": "D",
    "NWI_Wetland_Codes.WATER_REGIME_NAME": "Continuously  Saturated",
    "NWI_Wetland_Codes.WATER_REGIME_SUBGROUP": "Nontidal",
    "NWI_Wetland_Codes.WATER_REGIME_DEFINITION": "The substrate is saturated at or near the surface throughout the year in all, or most, years. Widespread surface inundation is rare, but water may be present in shallow depressions that intersect the groundwater table, particularly on a floating peat mat.",
    "NWI_Wetland_Codes.MODIFIER1": null,
    "NWI_Wetland_Codes.MODIFIER1_NAME": null,
    "NWI_Wetland_Codes.MODIFIER1_GROUP": null,
    "NWI_Wetland_Codes.MODIFIER1_SUBGROUP": null,
    "NWI_Wetland_Codes.MODIFIER1_DEFINITION": null,
    "NWI_Wetland_Codes.MODIFIER2": null,
    "NWI_Wetland_Codes.MODIFIER2_NAME": null,
    "NWI_Wetland_Codes.MODIFIER2_GROUP": null,
    "NWI_Wetland_Codes.MODIFIER2_SUBGROUP": null,
    "NWI_Wetland_Codes.MODIFIER2_DEFINITION": null,
    "NWI_Wetland_Codes.Field1": null,
    "boundedBy": [
      -9449462.0893,
      5779059.0402000025,
      -9446881.8671,
      5782546.794500001
    ]
  }
}

I think we are at the limits of Markup.js here. It only supports . for the separator, and doesn't support alternatives like properties["test.123"].

What I see as options:

1. Replace markup-js with something else. As markup-js hasn't been updated in over a decade, this might be the most reasonable option. I don't know if there is a replacement that exactly supports the Markup template syntax. I know there are several similar template engines. But if we change the template language in any not backwards compatible way, this would be a breaking change with significant user visible impact.
2. Fork markup-js and add support for parsing with brackets, so some other way to escape the . in the property name.
3. Launder the property names in GeoMoose before sending them to markup-js to replace the . with something it can deal with. This is probably the easiest, but might be slow (creating a second copy of each feature?), and creates weird behavior we'd probably end up having to support for backwards compatibility even if the markup-js situation is resolved.
4. Add a pipe or call function that works on properties and launders the names so people can include it only when necessary?

[theduckylittle]

I'm biased towards forking Markup-js if we decide its necessary. A decade-abandoned library may be a real indication we should start maintaining it ourselves. It's been built well enough to be durable for us, so tossing it in favor of something less compatible may not be worthwhile.

If we wanted to attack this without a full fork and update we could look at using pipes and adding a small special case pipe for getting values:

<div style="padding: 2px;">
  <b>Attribute: </b>{{ properties | getattr>Wetlands_CONUS_East.ATTRIBUTE}}
</div>

The diff would look something like this:

export const FORMAT_OPTIONS = {
 ...
  "getattr": (obj, attr) => {
     return obj[attr];
   },

But for this to work we would need to:

1. Figure out of getattr is the right name. I was inspired by python's getattr.
2. Write some documentation on how to use it and when.
3. Decide whether this is friendly enough.

[tchaddad]

I do think that would work and be fairly friendly!

This situation is likely only going to come up for large datasets served from an enterprise server and where attributes are being joined to the spatial data from multiple tables... we haven't seen too many of these, but I can imagine a few other federal datasets where this might happen (Soils comes to mind)...