Best way to load module class from lib folder in Rails 3

Question

Since the latest Rails 3 release is not auto-loading modules and classes from lib anymore  what would be the best way to load them   From github    A few changes were done in this commit   Do not autoload code in  lib  for applications  now you need to explicitly  require them   This makes an application behave closer to an engine   code in lib is still autoloaded for plugins

User · Answer

config autoload paths does not work for me  I solve it in other way     Ruby on rails 3 do not automatic reload  autoload  code from  lib folder  I solve it by putting inside ApplicationController   Dir  lib      rb   each do  path    require dependency path end

User · Answer

If only certain files need access to the modules in lib  just add a require statement to the files that need it   For example  if one model needs to access one module  add   require  mymodule    at the top of the model rb file

User · Answer

In my case I was trying to simply load a file directly under the lib dir    Within application rb     require   lib this file rb     wasn t working  even in console and then when I tried   require    lib this file rb     and rails loads the file perfectly    I m still pretty noob and I m not sure why this works but it works  If someone would like to explain it to me I d appreciate it  D I hope this helps someone either way

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As of Rails 2 3 9  there is a setting in config application rb in which you can specify directories that contain files you want autoloaded   From application rb     Custom directories with classes and modules you want to be autoloadable    config autoload paths     W   config root  extras

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Warning   if you want to load the  monkey patch  or  open class  from your  lib  folder  don t use the  autoload  approach        config autoload paths  approach  only works if you are loading a class that defined only in ONE place  If some class has been already defined somewhere else  then you can t load it again by this approach   config initializer load rb file rb  approach  always works  whatever the target class is a new class or an  open class  or  monkey patch  for existing class  it always works     For more details   see  https   stackoverflow com a 6797707 445908

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Spell the filename correctly    Seriously  I battled with a class for an hour because the class was Governance  ArchitectureBoard and the file was in lib governance architecture baord rb   transposed O and A in  board    Seems obvious in retrospect  but it was the devil tracking that down  If the class is not defined in the file that Rails expects it to be in based on munging the class name  it is simply not going to find it

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Autoload lib  folder including all subdirectories config autoload paths    Dir    config root  lib         Source  Rails 3 Quicktip  Autoload lib directory including all subdirectories  avoid lazy loading  Please mind that files contained in the lib folder are only loaded when the server is started  If you want the comfort to autoreload those files  read  Rails 3 Quicktip  Auto reload lib folders in development mode  Be aware that this is not meant for a production environment since the permanent reload slows down the machine

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The magic of autoloading stuff  I think the option controlling the folders from which autoloading stuff gets done has been sufficiently covered in other answers  However  in case someone else is having trouble stuff loaded though they ve had their autoload paths modified as required  then this answer tries to explain what is the magic behind this autoload thing   So when it comes to loading stuff from subdirectories there s a gotcha or a convention you should be aware  Sometimes the Ruby Rails magic  this time mostly Rails  can make it difficult to understand why something is happening  Any module declared in the autoload paths will only be loaded if the module name corresponds to the parent directory name  So in case you try to put into lib my stuff bar rb something like   module Foo   class Bar   end end   It will not be loaded automagically  Then again if you rename the parent dir to foo thus hosting your module at path  lib foo bar rb  It will be there for you  Another option is to name the file you want autoloaded by the module name  Obviously there can only be one file by that name then  In case you need to split your stuff into many files you could of course use that one file to require other files  but I don t recommend that  because then when on development mode and you modify those other files then Rails is unable to automagically reload them for you  But if you really want you could have one file by the module name that then specifies the actual files required to use the module  So you could have two files  lib my stuff bar rb and lib my stuff foo rb and the former being the same as above and the latter containing a single line  require  bar  and that would work just the same   P S  I feel compelled to add one more important thing  As of lately  whenever I want to have something in the lib directory that needs to get autoloaded  I tend to start thinking that if this is something that I m actually developing specifically for this project  which it usually is  it might some day turn into a  static  snippet of code used in many projects or a git submodule  etc   in which case it definitely should be in the lib folder  then perhaps its place is not in the lib folder at all  Perhaps it should be in a subfolder under the app folder   I have a feeling that this is the new rails way of doing things  Obviously  the same magic is in work wherever in you autoload paths you put your stuff in so it s good to these things  Anyway  this is just my thoughts on the subject  You are free to disagree        UPDATE  About the type of magic    As severin pointed out in his comment  the core  autoload a module mechanism  sure is part of Ruby  but the autoload paths stuff isn t  You don t need Rails to do autoload  Foo  File join Rails root   lib    my stuff    bar    And when you would try to reference the module Foo for the first time then it would be loaded for you  However what Rails does is it gives us a way to try and load stuff automagically from registered folders and this has been implemented in such a way that it needs to assume something about the naming conventions  If it had not been implemented like that  then every time you reference something that s not currently loaded it would have to go through all of the files in all of the autoload folders and check if any of them contains what you were trying to reference  This in turn would defeat the idea of autoloading and autoreloading  However  with these conventions in place it can deduct from the module class your trying to load where that might be defined and just load that

User · Answer

Very similar  but I think this is a little more elegant   config autoload paths    Dir    config root  lib      config root  lib

User · Answer

There are several reasons you could have problems loading from lib - see here for details - http   www williambharding com blog technology rails-3-autoload-modules-and-classes-in-production    fix autoload path threadsafe related naming relating

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I had the same problem  Here is how I solved it  The solution loads the lib directory and all the subdirectories  not only the direct   Of course you can use this for all directories     application rb config autoload paths     W   config root  lib  config autoload paths    Dir    config root  lib

User · Answer

As of Rails 5  it is recommended to put the lib folder under app directory or instead create other meaningful name spaces for the folder as services   presenters  features etc and put it under app directory for auto loading by rails   Please check this GitHub Discussion Link as well

[ruby-on-rails] Best way to load module/class from lib folder in Rails 3?

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