Get Files Filter Query

Why You Saw the Error:
Review_x0020_Date gt Approval_x0020_Date
in your filter query isn’t allowed because OData expects a literal on the right-hand side—not another column. This misinterpretation leads to the DateTime parsing error.

Empty (Null) Values:
When some items have an empty Approval Date, the query might misbehave if it isn’t properly filtered out.

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Field-to-Field Comparisons Are Not Supported:

Work Around This:

Since you can’t compare two date columns directly in the Get Files filter query, you’ll need to split the logic into two parts:

You can use the filter query to retrieve only those items that are “eligible” for further testing


FSObjType eq 0 and Approval_x0020_Date ne null and ToFilterNotifications ne 'Main'

Null Comparisons:
In many cases, filtering for ne null works. If you run into issues with that, you can sometimes work around it by using a constant that you know valid items will exceed. For example, if you know no valid Approval Date is before January 1, 2000, you might use:

Approval_x0020_Date gt datetime'2000-01-01T00:00:00Z'

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Compare Dates Within the Flow

Add a Condition Action: In your Flow, after the Get Files action, use a condition to compare the values.

Use an Expression to Compare Dates: Convert or format the dates if needed (for example, using the utcNow() or formatDateTime() functions).

EXAMPLE:
formatDateTime(item()?['Review_x0020_Date'], 'yyyy-MM-ddTHH:mm:ssZ')

and compare it with:
formatDateTime(item()?['Approval_x0020_Date'], 'yyyy-MM-ddTHH:mm:ssZ')