topic Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit? in ArcGIS Velocity Questions

Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

ArmstKP — Tue, 24 Jan 2023 21:46:20 GMT

I was wondering if it is possible to utilize ArcGIS Velocity to detect an attribute change/edit, to trigger another action, like sending a text message or email? Has anybody done this?

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

JeffEismanGIS — Thu, 26 Jan 2023 20:03:40 GMT

@ArmstKP yes it is possible to detect a attribute change in real time. One way to do this is to use Track functions - TrackFieldWindow

https://developers.arcgis.com/arcade/function-reference/track_functions/#trackfieldwindow

Track Functions can be use in the Calculate Field and Map Field tool arcade expressions:

Here is a sample workflow using a simple AVL feed tracking snow plows with a driver name attribute that could change as time passes.

Using DriverName and the TrackFieldWindow to send a notification when the change is detected.

TrackFieldWindow ( fieldName , startIndex , endIndex )

fieldName = driverName accessed as 'driverName'

startIndex = Past Feature (-1) accessed using TrackFieldWindow(-1,0)[0]

endIndex = Current Feature (0) accessed using $feature.driverName

// Get the prior observation value for the field using TrackFieldWindow
var priorValueArray = TrackFieldWindow('driverName', -1, 0)[0];

// Get the current feature observation value for the currentValue field
var currentValue = $feature.driverName;

// Handle the case where the first value does not have a prior feature
// If there is a prior value, determine if the value changed
if(count(priorValueArray) < 1){
return false;
} else {
return IIf(priorValueArray[0] != currentValue, true, false);
}

Then if the past feature and current feature are the same it returns - False

If past feature and current feature are different is returns - True indicating a attribute change.

Once you have that set you can leverage the filter tool to detect that change the send out a notification.

This is just one example but this workflow can be modified to reflect other use cases

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

ArmstKP — Wed, 25 Jan 2023 22:06:50 GMT

@JeffEismanGIS This is great! Thank you for such detailed step by step instructions as well! Much appreciated.

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

JeffEismanGIS — Wed, 25 Jan 2023 22:11:23 GMT

@ArmstKP Your welcome

Good Luck

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

ArmstKP — Wed, 25 Jan 2023 22:21:38 GMT

@JeffEismanGIS

I copied the expression that you wrote and added my field name in. I get this error, though. Any idea?

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

ArmstKP — Wed, 25 Jan 2023 23:00:07 GMT

@JeffEismanGIS Can you tell me why I might be getting the above error of "Out of Bounds"?

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

JeffEismanGIS — Wed, 25 Jan 2023 23:44:01 GMT

I have seen that error before. Is your feed running? If not start in and try it again. If it is running can you send me a sample of your data to look at. I think you have the option to message me directly.

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

JeffEismanGIS — Thu, 26 Jan 2023 14:02:24 GMT

@ArmstKP In looking a bit more into your problem there is one frontend limitation in array access of prior features, but we have a simple workaround that I could assist with on a call and screenshare. This will be fixed in our late Feb release.

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

brudo — Thu, 26 Jan 2023 18:19:31 GMT

@ArmstKP I wonder if it is because index -1 does not exist for the very first observation for a track, when the feed is started; and might not exist when the Velocity UI is evaluating the expression. Perhaps you could try adding "if (TrackIndex() > 0)" to the Arcade expression and only invoke TrackFieldIndex when that is true? (Just a hunch; honestly I have not tried using any of the Track functions in a Real Time Analytic and didn't even realize they would work there. Thanks @JeffEismanGIS for pointing that out!)

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

ArmstKP — Thu, 26 Jan 2023 18:30:01 GMT

@brudo @JeffEismanGIS Brudo, that is an interesting observation, I will have to look into it. I did make a change to the expression that Jeff posted above. I removed the '[0]' and the expression tested successfully...

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

PeterNasuti — Fri, 27 Jan 2023 17:09:49 GMT

@ArmstKP @brudo At the 3.3 Velocity release (current) the Arcade expression evaluation code is not capable of evaluating negative index values for Track functions. This shortcoming has already been fixed for our 4.1 release that will go live in production late February.

The workaround is to build your expression with positive values such as [1,2], and then to use the Velocity API to modify the value set in the analytic configuration for that expression. For assistance with that process please either create an Esri Support case or reach out to myself or @JeffEismanGIS directly via Esri community direct message to exchange contact information and schedule a call. As soon as our next release goes live in February, this extra step will no longer be required.

As an update to this, see @JeffEismanGIS 's edited comment above and @brudo 's suggestion

We can use an "if" function determination to assess the array length an if less than 1, we can return a false boolean type and not require any API level modifications prior to the Feb 2023 Velocity update.

// Get the prior observation value for the field using TrackFieldWindow var priorValueArray = TrackFieldWindow('driverName', -1, 0)[0]; // Get the current feature observation value for the currentValue field var currentValue = $feature.driverName; // Handle the case where the first value does not have a prior feature // If there is a prior value, determine if the value changed if(count(priorValueArray) < 1){ return false; } else { return IIf(priorValueArray[0] != currentValue, true, false); }

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

ArmstKP — Thu, 26 Jan 2023 18:45:41 GMT

@PeterNasuti Thank you for the context of the issue. I have reached out to @JeffEismanGIS via DM.

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

brudo — Thu, 26 Jan 2023 19:26:34 GMT

@ArmstKP that makes sense - so it seems the Track function is forgivingly clipping its result to the available range and returning an empty array when called for the first feature; but the index into the resulting zero-length array is raising that error. In that case you could use "if (Count(trackResult) > 0)" interchangeably with checking the TrackIndex up front. Or alternatively, you could just call "First(TrackFieldWindow(...))" instead of "TrackFieldWindow(...)[0]", which will then return null for an empty array. And to be sure, there are other ways as well.

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

brudo — Thu, 26 Jan 2023 19:40:04 GMT

Thanks @PeterNasuti, but is that true? I just tested the expression "First(TrackFieldWindow('fieldName', -1,0))" within the Velocity UI in a random RTA, and it evaluates to null as expected, without raising an error. Are you sure the fix you mentioned was not snuck into the current release after all? I did not actually try to run it.

On the other hand, I would expect positive values to always fail in an RTA, and only work in a BDA, since it is processing the current incoming record and has not yet seen the future records at the time of evaluation...

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

PeterNasuti — Thu, 26 Jan 2023 20:01:37 GMT

@brudo We had a call with @JeffEismanGIS and @ArmstKP to implement the workaround for the frontend limitation at the current 3.3 release. As soon as 4.1 goes live in late February this limitation will no longer be present.

You are correct that in real-time analytics positive values are not valid for backend evaluation, but they are valid for big data analytics. At the current release we do not have a way to insert that nuance to the Arcade expression evaluation but we are considering validation inspection options for future releases.

Expect more examples, conference demos, and community videos from the real-time time moving forward on the use of track functions highlighting use cases and configurations. In the meantime feel free to log a support case or direct message a Velocity team member for assistance with the workaround for this negative value specification at the current release.

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

ArmstKP — Tue, 19 Sep 2023 16:41:54 GMT

@JeffEismanGIS Do you know if the updates have gone through for this as of yet?

I have followed your example in the last few days and the expression/calculate field for "DidDriverNameChange_String" boolean type. I have changed the field names in the expression to represent my test source layer and it tests successfully, but it will error out at this expression/calculate field tool when running the BDA...

Re: Is It Possible to Utilize Velocity to Detect Attribute Change/Edit?

JeffEismanGIS — Tue, 19 Sep 2023 16:54:26 GMT

@ArmstKP Thanks for the follow up, what is the error you are getting when you run the Big data analytic.