RethinkDB filters work on regular expressions. To do starts with queries, you can match the regular expression on the start of the data:
r.db('test')
.table('users')
.filter( (doc) => doc('user_name').match("^.*ielin") )
Note that the end isn’t matched, so it will include results with various ends.
first_name
|
id
|
last_name
|
user_name
|
|
1
|
gary
|
72b719a2-0a96-4b54-aaba-63b76e5c3c75
|
sieling
|
gsieling
|