The matcher/matchable corresponds to the Mongo $ne operator which treats array-valued attributes in a special way: It selects documents whose attribute does not contain the specified value.

Say, we have a collection of documents like this:

[

{ id: 1, state: ['locked'] }

,

{ id: 2, state: [] }

]

Now,

Doc.where(state: 'locked')

matches only the first document and the Default matcher/matchable mirrors this behavior.

However,

Doc.ne(state: 'locked')

matches only the second document, whereas the Ne matcher/matchable matches both.

I suggest that Ne::matches? be implemented like this:

def matches?(value)
#@attribute != value.values.first
!super(value.values.first)
end