# Find\_or\_create\_xxx behaving differently than create **URL:** \ **Category:** Rails\ **Created:** [May 16, 2010, 8:56am UTC](https://www.ruby-forum.com/t/find-or-create-xxx-behaving-differently-than-create/188677 "2010-05-16T08:56:47Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![fearless\_fool](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/5e9695/32.png) [@fearless\_fool](https://www.ruby-forum.com/u/fearless_fool)\ **Post date:** [May 16, 2010, 8:56am UTC](https://www.ruby-forum.com/t/find-or-create-xxx-behaving-differently-than-create/188677/1 "2010-05-16T08:56:47Z")
It appears that find\_or\_create\_by\_xxx is attempting type conversion where a simple create(…) does not. Bug? Before going further, here’s the schema and the model: create\_table “weather\_stations”, :force =\> true do |t| t.string “callsign” t.decimal “lat”, :precision =\> 9, :scale =\> 6 t.decimal “lng”, :precision =\> 9, :scale =\> 6 t.decimal “elevation\_m”, :precision =\> 5, :scale =\> 1 end class WeatherStation \< ActiveRecord::Base validates\_presence\_of :callsign, :lat, :lng validates\_uniqueness\_of :callsign, :case\_sensitive =\> false acts\_as\_mappable … end [Note the “validates\_uniqueness\_of :callsign, :case\_sensitive =\> false” – that comes into play here.] \*\* Assume ‘specs’ is a hash whose :callsign is a string: > > specs > > =\> {:callsign=\>“0N6”, :lat=\>39.0128889, :lng=\>-75.5339722, > > :elevation\_m=\>15.0} > > > specs[:callsign].class > > =\> String \*\* The call to find\_or\_create\_by\_callsign fails – note that id comes back nil and the other fields are not filled in: > > w = WeatherStation.find\_or\_create\_by\_callsign(specs[:callsign], :lat =\> specs[:lat], :lng =\> specs[:lng]) > > =\> #\ > nil, updated\_at: nil, lat: nil, lng: nil, elevation\_m: nil\> \*\* The generated SQL shows a rollback: WeatherStation Load (22.2ms) SELECT \* FROM `weather_stations` WHERE (`weather_stations`.`callsign` = ‘0N6’) LIMIT 1 SQL (0.4ms) BEGIN WeatherStation Load (230.6ms) SELECT `weather_stations`.id FROM `weather_stations` WHERE (LOWER(`weather_stations`.`callsign`) = BINARY ‘0n6’) LIMIT 1 SQL (1.0ms) ROLLBACK \*\* Using a simple .create() instead works: > > x = WeatherStation.create(:callsign =\> specs[:callsign], :lat =\> specs[:lat], :lng =\> specs[:lng]) > > =\> #\ > “2010-05-16 06:38:22”, updated\_at: “2010-05-16 06:38:22”, lat: > > #BigDecimal:8db79b0,‘0.390128889E2’,12(16), lng: > > #BigDecimal:8db7828,’-0.755339722E2’,12(16), elevation\_m: nil\> \*\* …but looking at the SQL shows that it does the same check for uniqueness before inserting the row. Since the record isn’t in the table, it’s okay that it fails: SQL (70.0ms) BEGIN WeatherStation Load (365.4ms) SELECT `weather_stations`.id FROM `weather_stations` WHERE (LOWER(`weather_stations`.`callsign`) = BINARY ‘0n6’) LIMIT 1 WeatherStation Create (2.0ms) INSERT INTO `weather_stations` (`callsign`, `domain`, `created_at`, `updated_at`, `lat`, `lng`, `elevation_m`) VALUES(‘0N6’, NULL, ‘2010-05-16 06:38:22’, ‘2010-05-16 06:38:22’, 39.0128889, -75.5339722, NULL) SQL (3.3ms) COMMIT I don’t understand enough about SQL’s “BINARY ‘0n6’” – is that the source of the trouble? Or is my validation bogus? Why is find\_or\_create\_by\_callsign() failing? TIA. - ff ---
**Author:** ![fearless\_fool](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/5e9695/32.png) [@fearless\_fool](https://www.ruby-forum.com/u/fearless_fool)\ **Post date:** [May 16, 2010, 12:12pm UTC](https://www.ruby-forum.com/t/find-or-create-xxx-behaving-differently-than-create/188677/2 "2010-05-16T12:12:20Z")
On May 16, 8:56 am, Fearless F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I don’t understand enough about SQL’s “BINARY ‘0n6’” – is that the > source of the trouble? Or is my validation bogus? Why is > find\_or\_create\_by\_callsign() failing? I think it’s far more likely that it’s the nil attributes you noted that are the problem - they would certainly prevent the record from being saved. It appears that find\_or\_create\_by doesn’t quite work the way you expected it to - the code and unit tests suggests that you should be doing WeatherStation.find\_or\_create\_by\_callsign(:callsign =\> specs[:callsign], :lat =\> specs[:lat], :lng =\> specs[:lng]) There is an another example in the docs of the usage you were attempting though, looks like it is just wrong/misleading. Fred ---
**Author:** ![fearless\_fool](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/5e9695/32.png) [@fearless\_fool](https://www.ruby-forum.com/u/fearless_fool)\ **Post date:** [May 16, 2010, 5:27pm UTC](https://www.ruby-forum.com/t/find-or-create-xxx-behaving-differently-than-create/188677/3 "2010-05-16T17:27:52Z")
Frederick C. wrote: > … > It appears that find\_or\_create\_by doesn’t quite work the way you > expected it to - the code and unit tests suggests that you should be > doing > > WeatherStation.find\_or\_create\_by\_callsign(:callsign =\> > specs[:callsign], :lat =\> specs[:lat], :lng =\> specs[:lng]) You are correct – that works as expected. > There is an another example in the docs of the usage you were > attempting though, looks like it is just wrong/misleading. Correct again! The line in the doc is: # No ‘Summer’ tag exists Tag.find\_or\_create\_by\_name(“Summer”) # equal to Tag.create(:name =\> “Summer”) which passes “Summer” rather than :name =\> “Summer”. Sigh. A guy I used to work with told me that there is only one “authoritative documentation”, and that’s the source code itself. Evidently, Rails subscribes to this philosophy as well. ---
**Author:** ![fearless\_fool](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/5e9695/32.png) [@fearless\_fool](https://www.ruby-forum.com/u/fearless_fool)\ **Post date:** [May 16, 2010, 5:59pm UTC](https://www.ruby-forum.com/t/find-or-create-xxx-behaving-differently-than-create/188677/4 "2010-05-16T17:59:28Z")
On 16 May, 17:27, Fearless F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Frederick C. wrote: > > > … > > There is an another example in the docs of the usage you were > > attempting though, looks like it is just wrong/misleading. > > Correct again! The line in the doc is: > > # No ‘Summer’ tag exists > > Tag.find\_or\_create\_by\_name(“Summer”) # equal to Tag.create(:name =\> > “Summer”) Actually that usage is correct too. The misleading example is actuall demonstrating a different point. > which passes “Summer” rather than :name =\> “Summer”. > > Sigh. A guy I used to work with told me that there is only one > “authoritative documentation”, and that’s the source code itself. > Evidently, Rails subscribes to this philosophy as well. A fair amount of effort has gone into the rails documentation of late. Like the rest of rails it only gets better if people contribute ---
**Author:** ![fearless\_fool](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/5e9695/32.png) [@fearless\_fool](https://www.ruby-forum.com/u/fearless_fool)\ **Post date:** [May 16, 2010, 6:36pm UTC](https://www.ruby-forum.com/t/find-or-create-xxx-behaving-differently-than-create/188677/5 "2010-05-16T18:36:25Z")
Frederick C. wrote: > A fair amount of effort has gone into the rails documentation of late. > Like the rest of rails it only gets better if people contribute Agreed. But, as evidenced by my sometimes boneheaded questions in this forum, Rails would be in serious trouble if I were a contributor! 🙂 (At least for now…)