Support deriving ES index from document contents

Community member Parkash Bansak writes:

For an instance I have a following record:

{

“field1”: “foo”,

“field2”: “bar”

…

}

I want to creating a ES type mapping where I want to filter the records based on values of field1 and field2. Something like this,

if (field1=foo && field2=bar) ==> send the record to ES index equal to “index_1”

Or Alternatively
Can we create a ES type mapping where I just create a regex for dynamically calculating the index name based on the combination of field1 & field2. So the above record should go to index equal to “index_foo_bar” ?

Just to clarify I want to avoid creating document id based on the combination of these fields.