Fix ids filter

[jrhoads]

Purpose

Fix an issue with the ids filter.

closes: #998

Approach

Re-adds the check to convert a single string into an array, by splitting on commas.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• Breaking change (fix or feature that would cause existing functionality to change)

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