Uploading a file in Rails

Question

I m new to rails  and I m writing a RESTful website using the CRUD technique  So far I have created three pages  all of which allow the user to create  edit  and delete a row from the database  However  my fourth page will need to include an upload file form  but a  I don t know how the filesystem works with Rails thus I don t know where files should be stored  The file would be around 100kb and couldn t be stored in temporary storage because it will be constantly downloaded  And b  I don t know how to write to a file   It would be great if you could tell me how to do what I mentioned above - create an upload input on an input form  and to then write the file to a filepath in a separate directory

User · Answer

Sept 2018  For anyone checking this question recently  Rails 5 2  now has ActiveStorage by default  amp  I highly recommend checking it out   Since it is part of the core Rails 5 2  now  it is very well integrated  amp  has excellent capabilities out of the box  still all other well-known gems like Carrierwave  Shrine  paperclip     are great but this one offers very good features that we can consider for any new Rails project   Paperclip team deprecated the gem in favor of the Rails ActiveStorage   Here is the github page for the ActiveStorage  amp  plenty of resources are available everywhere  Also I found this video to be very helpful to understand the features of Activestorage

User · Answer

Update 2018  While everything written below still holds true  Rails 5 2 now includes active storage  which allows stuff like uploading directly to S3  or other cloud storage services   image transformations  etc  You should check out the rails guide and decide for yourself what fits your needs     While there are plenty of gems that solve file uploading pretty nicely  see https   www ruby-toolbox com categories rails file uploads for a list   rails has built-in helpers which make it easy to roll your own solution   Use the file field-form helper in your form  and rails handles the uploading for you    lt    form for  person do  f    gt     lt    f file field  picture   gt   lt   end   gt    You will have access in the controller to the uploaded file as follows   uploaded io   params  person   picture  File open Rails root join  public    uploads   uploaded io original filename    wb   do  file    file write uploaded io read  end   It depends on the complexity of what you want to achieve  but this is totally sufficient for easy file uploading downloading tasks  This example is taken from the rails guides  you can go there for further information  http   guides rubyonrails org form helpers html uploading-files

User · Answer

There is a nice gem especially for uploading files   carrierwave  If the wiki does not help   there is a nice RailsCast about the best way to use it   Summarizing   there is a field type file in Rails forms   which invokes the file upload dialog  You can use it   but the  magic  is done by carrierwave gem     I don t know what do you mean with  how to write to a file    but I hope this is a nice start

User · Answer

Okay  If you do not want to store the file in database and store in the application  like assets  custom folder   you can define non-db instance variable defined by attr accessor  document and use form for - f file field to get the file   In controller     person   Person new person params    Here person params return whitelisted params  person   define yourself   Save file as   dir      Rails root  app assets custom path  FileUtils mkdir dir  unless File directory  dir document    person document document file name   check document uploaded params File copy stream  font document     dir    document      Note  Add this path in  gitignore  amp  if you want to use this file again add this path asset pathan  of application by application rb  Whenever form read file field  it get  store in tmp folder  later you can store at your place  I gave example to store at assets  note  Storing files like this will increase the size of the application  better to store in the database using paperclip

User · Answer

In your intiallizer carrierwave rb  if Rails env development     Rails env test      config storage    file     config root      Rails root  public      if Rails env test        CarrierWave configure do  config          config storage    file         config enable processing   false       end     end  end   use this to store in a file while running on local

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