How to calculate the sum of the values in an attribute from the FeatureSet results of a QueryTask

Permanently deleted user

April 05, 2018 21:40

I am trying to find the sum of all values from an attribute (add up total acres).  I have a QueryTask activity that finds a subset of values from a feature class and puts the results in a FeatureSet.  How do I then get the Out Statistics value for "sum"?  I created a variable for the "Group By Fields for Statistics" argument - an IList String called acres with the value ACRES.  And I created an Out Statistics variable (outStats) of type iList <ESRI.ArcGIS.Client.Tasks.OutStatistic>.  The original attribute is of type Double.

 

But now I don't know how to access any of the stats values. I have tried various assigns, conversions to DataTable, ForEach activities, etc... but I can't get the syntax right and I can't find any help or examples on the ArcGIS or Geocortex help.

 

Any thoughts? Or is there a better way to do this?

Thanks,

 

Mike

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  Nico Burgerhart

  April 05, 2018 22:03

  Set the Out Statistics property to something like New System.Collections.Generic.List(Of ESRI.ArcGIS.Client.Tasks.OutStatistic)({ New ESRI.ArcGIS.Client.Tasks.OutStatistic("OnField", "OutField", ESRI.ArcGIS.Client.Tasks.StatisticType.Sum) }) Fill the Group By Fields for Statistics only if you want to group.

   

   

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  Zack Robison

  April 05, 2018 23:02

  Alternatively to Nico's excellent answer, you can use LINQ on your existing featureset that you've already derrived from the query.  You expression would look something like:

   

  <featureSet>.Features.Sum( Function(feat) CDbl(feat.Attributes("<StatisticFieldName>") )

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  Nico Burgerhart

  April 06, 2018 07:10

  The workflow designer gives examples for the syntax of the Out Statistics property, if you disable the IntelliSense feature.

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  Permanently deleted user

  April 06, 2018 13:19

  Thanks very much for your help!  I used your code Nico in the Out Statistics field, replacing "OnField" with the field I want to compute statistics for - "ACRES".  But I am not sure what to do with "OutField".  Do I need to create a whole new field in the featureSet?  I just put a variable there, but that gives me an unhandled exception.

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  James Brink

  April 09, 2018 19:14

  Mike

   

  I let the users get the total Appraised and Assessed values of the properties for the polygon they draw on the map and display the results in a popup.

   

  1) Get the geometry and capture the parcels in the geometry.

   

  2) Sum the Appraised_Total (Appraised value per parcel) using the OutStatistic, send results to new feature set.

   

  New List( Of OutStatistic) From { New OutStatistic( "APPRAISED_TOTAL" , "SUM_APPRAISED" , StatisticType.Sum) }

   

  3) Get the value and display the result - 

   

  item.Attributes.Item("SUM_APPRAISED").ToString

   

  Maybe this will help.

   

   

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  Permanently deleted user

  April 09, 2018 22:07

  Thanks for the additional pointers, Jimmy.  I am just really having trouble figuring out how to pass the value around in the Workflow Designer so I can actually access it.  I can confirm I am getting features with the QueryTask.  But then how to pass the output of the Out Statistics back to the user as a variable? I will be passing it along to create a report.

   

  Here is a screenshot showing where I am confused.  I am trying to pass the SUM value to the variable dTotal_Acres.  But no matter what I try I am unable to get it to work. In addition I am now getting a "Unhandled exception: 'One or more errors occurred.' in activity '1.1154: QueryTask'" whereas before I could actually get through the QueryTask!

   

  

   

   

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  James Brink

  April 10, 2018 13:31

  Mike

   

  So, maybe there is something about trying to do OutStatistics on the SHAPE.AREA. I tried and I got the error message that you got. I copied the SHAPE.AREA field to AREA (new field) and the OutStatistics worked on it.

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  Permanently deleted user

  April 10, 2018 14:04

  Hey Jimmy,

   

  Thanks for the follow up.  But  I am not doing OutStatistics on the SHAPE.AREA field.  It is on a user inputted field called ACRES, which is of type double (this is for a point layer, so no area field at all).  The outField I just made up ("acresSUM").  It does not appear anywhere else.  I am not really sure how the outField works, to be honest.  Do you just make up a string and then call it somewhere else?  Do you have to create a variable for it?

   

  Thanks for your help!

   

  Mike

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  James Brink

  April 10, 2018 15:04

  Mike

   

  Can you send me an email and I will send you my workflow?

   

   

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  Permanently deleted user

  April 17, 2018 14:04

  Thanks everyone, your suggestions and help were correct.   It took me some time and help to fix because my workflow had another issue that conflicted somehow with the Out Statistics argument.  I had a value in the Order By Fields argument that worked by itself.  When I added the Out Statistics argument the QueryTask activity reported an error.  When I then removed the Order By Fields argument the QueryTask activity and Out Statistics worked.

   

  Thanks everyone, I appreciate the support.

   

  Mike

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