undefined method `+#' for nil:NilClass rails after moving to mysql - mysql

Question

I moved the database to mysql which is on VM. After moving database I started getting this error when I am trying to access or saving data to database but some models updation are working fine.
The model I am accessing has some arithmetic computations which I feel is the reason for this issue.
Error is
undefined method `+#' for nil:NilClass
I tried from rails console as well and I am getting same error with this command
Settings.all
I guess this is part of that method method
if params[:lat] and params[:lon] and params[:rad] and !params[:lat].empty? and
!params[:lon].empty? and !params[:rad].empty?
lat = params[:lat].to_f
lon = params[:lon].to_f
rad = params[:rad].to_f
ear = 6371.00
min_lat = (lat) - (rad/ear)/180.0*Math::PI;
max_lat = (lat) + (rad/ear)/180.0*Math::PI;
min_lon = (lon) - (rad/ear/Math.cos(lon*Math::PI/180.0))/180.0*Math::PI;
max_lon = (lon) + (rad/ear/Math.cos(lon*Math::PI/180.0))/180.0*Math::PI;
#settings = #settings.includes(:settings_location)
.where("settings_locations.latitude > :min_lat AND " \
"settings_locations.latitude < :max_lat AND " \
"settings_locations.longitude > :min_lon AND " \
"settings_locations.longitude < :max_lon", {
min_lat: min_lat,
max_lat: max_lat,
min_lon: min_lon,
max_lon: max_lon});
stack trace
Started POST "/settings.json" for 127.0.0.1 at 2014-04-24 13:52:53 +0200
NoMethodError - undefined method `+#' for nil:NilClass:
app/models/settings.rb:54:in `<top (required)>'
activesupport (4.0.2) lib/active_support/dependencies.rb:424:in `block in load_file'
activesupport (4.0.2) lib/active_support/dependencies.rb:616:in `new_constants_in'
activesupport (4.0.2) lib/active_support/dependencies.rb:423:in `load_file'
activesupport (4.0.2) lib/active_support/dependencies.rb:324:in `require_or_load'
activesupport (4.0.2) lib/active_support/dependencies.rb:463:in `load_missing_constant'
setting.rb:
class Settings < ActiveRecord::Base
has_one :settings_location
def to_builder
Jbuilder.new do |json|
json.location settings_location.to_builder
end
end //this line is 54

Answer 1

Per the comments, there seem to be only a handful of cases where you can reproduce the same error message in IRB. The first is:
foo, bar = nil, nil
foo.send("+#", bar) # undefined method `+#' for nil:NilClass
The second is:
foo = nil
+foo # undefined method `+#' for nil:NilClass
In an eval context, the latter might more look like:
foo, bar = nil, nil
eval("foo = +#{bar.inspect}") # undefined method `+#' for nil:NilClass
My personal guess is that your problem is something along the lines of the latter. Not with eval, but rather with one of its plethora of Ruby variations such as define_method. The actual call is very likely somewhere in Rail's internals and related to some uninitialized variable — perhaps MySQL is returning null where SQLite was returning something due to a recent schema change that you didn't think about?
Personally, I'd try to narrow it down step by step:
1. Comment out:
json.location settings_location.to_builder
If the error is gone, then:
2.a) Replace it with:
builder = settings_location.to_builder
json.location builder
If the error message is still the same, then:
2.b) Try
Jbuilder.new
… without a block.
The point is, you want to narrow things down to the specific method that is causing the error, and then dive into that method's code to see what is nil and shouldn't be. (Perhaps the block is missing some kind of return value?)