Lucene Search for documents that have a particular field?

Lucene.Net - Is there a way to query for documents that contain a particular field.

Lets say some of my do开发者_开发技巧cuments have a field 'foo' and some do not.

I want to find all documents that have the field 'foo' - regardless of what the value of foo is.

How do I do this? Is it some sort of TermQuery?

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Try foo:[* TO *] should work for all non-null values of field 'foo'