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Handling nulls with ADO child item count

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Posted on by nbrown02

Hi all,

I am creating a flow that will populate a "rightsized" field (Yes/No) on ADO depending on if the child item count for a Feature is above/below a certain value.

The flow works fine when there are child items but doesn't like when there are no child items, instead just ignoring those items (they should always be populated with "Yes")

The Parse JSON action has an output like so:

{

"@odata.context": "https://analytics.dev.azure.com/[ORGName]/[ProjectName]/_odata/v3.0-preview/$metadata#WorkItems(WorkItemId,Descendants(Count,DescendantCount))",

"vsts.warnings@odata.type": "#Collection(String)",

"@vsts.warnings": [

"VS403508: Using the Parent, Children, Descendants or Revision properties in a filter or expand is not recommended. Details on recommended query patterns are available here: https://go.microsoft.com/fwlink/?linkid=861060."

"value": [

{

"WorkItemId": 1004599,

"Descendants": []

}

]

}

But I can't seem to create a condition where it handles this null/empty value...any tips? (flow attached)

Categories:

Building flows

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Mark Nanneman 991 Super User 2025 Season 2 on at

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I don't ever use ParseJSON personally because it's too much trouble when it comes to dealing with nulls or other variations in the data schema. You should be able to reference the array of child items directly without using parseJSON.

I don't know what your flow looks like but assuming "Yes" or True is supposed to be the default in situations where the Rightsized column is blank, you could probably solve this with a coalesce() expression on your Create or Update action.

Coalesce goes with the first non-null item in a list of comma seperated items--so whatever the default should be goes at the end.

It would be something like Coalesce(varRightized, true) where varRightsized is a boolean value and true is the default you want.

That's a failsafe method, it would be best to fix the condition that drives how you get the Yes or No. Post a screenshot of this if you could. Another thing you can do, if you're using a variable to store "yes" or "no" (or True / False) is you can set that variable to the default value you want before your logic is run.

Hope that makes sense

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MiDer 139 on at

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Hey Nick

you should let your dummy user vanish ...

How about one of the following approaches:
Rather than
"expression": { "and": [ { "greater": [ "@items('Apply_to_each_4')?['DescendantCount']", "@variables('Rightsize')" ] }, { "or": [ { "contains": [ "@body('HTTP_2')", "\"Descendants\": []" ] } ] } ] },

try

@equals(empty(body('http_2')?['Descendants'],true)

or

@equals(body('http_2')?['Descendants']?[0],null)

On a general note, if you just need to evaluate the related item count on the first level the property 'relations' from this URI could do the trick as well:

/_apis/wit/workItems/@{variables('DataObject')?['payload']?['WorkItemBaseID']}?$expand=all

In case you are interested in certain hierarchy types only, filter them out via select:

@and(
equals(
item()?['rel'],
'System.LinkTypes.Hierarchy-Forward'
),
not(
equals(
item()?['attributes']?['Name'],
'Parent'
)
)
)

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