WebApp builder: Dynamic legend based on view window

05-20-2021 06:04 PM
Status: Open
New Contributor III


Current, we have a map with many layers, which are area-based features. The way I see it currently working is that the application takes in the zoom level to define the dynamic legend, not the view window. Meaning that something that is not within the view window is still populated in the legend. It would be great to have a setting to use the view window to define the legend.

see: https://ergon.maps.arcgis.com/apps/webappviewer/index.html?id=5a53f6f37db84158930f9909e4d30286

Thank you


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1 Comment

Hi Thorsten! 
This is a good idea, thanks for articulating it and sending it to the community.

There are ways to achieve similar functionality, but the ones I'm thinking of aren't exactly what you describe. Here's why:

If the legend changed dynamically with the map window, each and every movement by any user on the planet would initiate a different query. The extent of their map window would be unique--to their browser, their machine, etc.

Much of what we engineer in ArcGIS Online aims to facilitate repeatable queries--those for which responses can be cached on edge servers which are close to the end users. This is how ArcGIS Online scales its maps and apps to meet the viral demands of Covid dashboards, utility outage viewers, etc.

So although we might be able to engineer what you're describing, for an application which generates high usage, I'd recommend using repeatable queries consistently.

We're always pushing the technology, so the story isn't over yet... we'll see what the future holds.

In the meantime, you can learn more about repeatable queries and response caching here: https://www.esri.com/arcgis-blog/products/data-management/data-management/scalable-hosted-feature-la...

And in another week or so, we'll have some links available from our 2021 Developers Summit which dive deeper into the details. I'll make sure to post them here for your review.

Hope that's helpful!