Object reference not set to an instance of an object

Chris Bates

5. November 2019 21:37

Hi all,

 

 

I've got a fairly simple workflow set up with a query task to get records from a mapservice, return the results and zoom to the extent of the selected features. I'm running into the following error when trying to run it in my application:

 

 

Alert

 

There was a workflow error running activity: Exception has been thrown by the target of an invocation.

 

Workflow 'ZoneSearch' failed.

 

Unhandled exception: 'Object reference not set to an instance of an object.' in activity '1.9: Set Map Extent'.

 

Object reference not set to an instance of an object.

 

 

-The SetMapExtent is the final activity in the workflow.

 

-The Input Argument is extent.Expand(3)

 

-extent is an input Variable Type: Envelope Scope: Flowchart. It is also the result of the GetFeatureSetExtent activity (which comes before SetMap Extent.

 

 

My apologies for the complicated explanation - its really difficult to explain the issue without being able to add screen shots to the post. 

 

 

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  Nico Burgerhart

  5. November 2019 22:40

  Does your FeatureSet contain geometry (Return Geometry is True on the Query Task)?

   

  Are there features in the FeatureSet (FeatureSet.Features.Any should return True)

   

  If you FeatureSet contains one point feature: a point has no extent.

   

  Does your FeatureSet return features (Return OIDs Only is False).

   

  Check the contents of the FeatureSet with the .ToJson method.

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  Chris Bates

  5. November 2019 23:46

  Thanks for the reply Nico,

   

   

  Hopefully I can cover all of your points:

   

   

  1. QueryTask...Return Geometry = True

   

  2. QueryTask goes through a Flow Decision Node (FeatureSet.Features.Count = 0) 

   

   

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  Chris Bates

  5. November 2019 23:50

  Argh, sorry I can't seem to end my post and i posted too early...

   

   

  2. QueryTask goes through a Flow Decision Node (FeatureSet.Features.Count = 0) 

   

           if True return No Features Found

   

           if False Select FeaturesSet

   

   

  3. The input feature class is a polygon only. No points.

   

   

  4. Can you elaborate on using the .ToJson method to check the contents of the FeatureSet?

   

   

  Thanks again

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  Nico Burgerhart

  6. November 2019 10:25

  .ToJson returns a json representation of the featureset, you can use an alert activity to show the contents.

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  Chris Bates

  6. November 2019 16:45

  Okay - great, the contents of the FeatureSet makes sense (contains the the correct information for the correct mapservice).

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  Nico Burgerhart

  6. November 2019 18:17

  There is geometry in it? Because the issue should be in the geometry.

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  Chris Bates

  6. November 2019 19:48

  Hi Nico - you were absolutely correct. The geometry was not coming across (The SHAPE@ fields were not visible in the ArcGIS Pro project that publishes the map service) So, that explains why the query task was able to return tabular information but returning a null value for geometry and then bombing when trying to get the extent info. 

   

   

  Thanks for you help. The .ToJSON method was very helpful in debugging the issue.

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  Nico Burgerhart

  11. November 2019 09:20

  The OBJECTID is correctly filled?

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  Permanently deleted user

  12. November 2019 08:54

  yes and the error appears when in the buffer tool,

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  Permanently deleted user

  12. November 2019 08:55

  and when I drop the alert message I got the result.

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  Nico Burgerhart

  12. November 2019 09:47

  Set Return Geometry on the Query Task to True.

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  Permanently deleted user

  14. November 2019 08:05

  Thank you Nico for your help, it is already set to true, I could confirm that the issue is resolved by entering the service url instead of the layer url. This was my silly mistake!

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