How to nest .or() and .and() conditions in Mongoid - mongodb

Question

I have a 'search' function where I want to pass in an arbitrary 'filter' condition and have matches returned
The following matches any name/email where the filter string is a match:
#people = Person.all
#people = #people.or(
{'name.first_name' => /#{filter}/i},
{'name.last_name' => /#{filter}/i},
{'email' => /#{filter}/i }
)
The following correctly does the same on the 'tags' array on the Person record:
#people = Person.all
#people = #people.any_in('tags' => [/#{filter}/i])
Can anyone tell me how to combine the two queries, so that a Person is matched if the filter text is found in the name, email or any of the tags?

Answer 1

It turns out there is a method I was missing here ... found indirectly via https://github.com/mongoid/mongoid/issues/2845
Given these two queryables:
a=Person.where({'name.first_name'=> /a/i})
b=Person.where({'name.first_name'=> /j/i})
You can combine them using .selector
Person.or(a.selector, b.selector).to_a
=> selector={"$or"=>[{"name.first_name"=>/a/i}, {"name.first_name"=>/j/i}]}
or
Person.and(a.selector, b.selector).to_a
=> selector={"$and"=>[{"name.first_name"=>/a/i}, {"name.first_name"=>/j/i}]}

Answer 2

You don't need to use any_in at all. If say:
:array_field => regex
then MongoDB will automatically check each element of array_field against regex for you, you don't have care about the arrayness at all. That means that you can toss the :tags check in with the other conditions:
regex = /#{filter}/i
#people = Person.where(
:$or => [
{ 'name.first_name' => regex },
{ 'name.last_name' => regex },
{ 'email' => regex },
{ 'tags' => regex }
]
)
I also pull the regex out of the query into a variable to make it clear that you're using the same one for each check and I switched to where as that's more common (at least in my experience).