Using insert_one stops Mongoid from being able to update the record

[KieranP]

I've run into a weird issue where using insert_one to insert a record works, but then that record can't be updated in Mongo. base_salary in this case is a BigDecimal field. Note how the following base_salary field shows as updates after the set command, but is not being persisted.

attrs = Employee.new(base_salary: "123")
Employee.collection.insert_one(**attrs)

e = Employee.last

puts e.base_salary.to_s
=> "123.0"
puts e.read_attribute_before_type_cast(:base_salary)
=> "123"

e.set(base_salary: "124")

puts e.base_salary.to_s
=> "124.0"
puts e.read_attribute_before_type_cast(:base_salary)
=> "124"

e.reload

puts e.base_salary.to_s
=> "123.0"
puts e.read_attribute_before_type_cast(:base_salary)
=> "123"

Employee.collection.update_one(
  { _id: e.id },
  { '$set': { base_salary: "124" } },
)

e.reload

puts e.base_salary.to_s
=> "123.0"
puts e.read_attribute_before_type_cast(:base_salary)
=> "123"

e = Employee.last
puts e.base_salary.to_s
=> "123.0"
puts e.read_attribute_before_type_cast(:base_salary)
=> "123"

I'm really struggling to figure out why this would be. Anyone got any ideas?

Also files bug report here: https://jira.mongodb.org/browse/MONGOID-5824

[alexbevi]

Thanks for filing the associated JIRA ticket @KieranP. We'll carry on the discussion there :)