Rails Download File from Path Ruby on Rails 2.1 - File Uploading
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rails download file from path Ruby on Rails 2.1 - File Uploading. You may have a requirement in which you want your site visitors to upload a file on your server. Rails makes it very easy to handle this requirement. Now, we will proceed with a simple and small Rails project. As usual, let's start off with a new Rails application called upload . Let's create a basic structure of the application by using simple rails command. Let's decide where you would like to save your uploaded files. Assume this is data directory inside your public section. So, create this directory and check the permissions. Our next step will be as usual, to create controller and models. Creating the Model. As this is not a database-based application, we can keep whatever name is comfortable to us. Assume we have to create a DataFile model. Now, we will create a method called save in data_file.rb model file. This method will be called by the application controller. The above function will take the CGI object upload and will extract the uploaded file name using the helper function original_filename and finally, it will store the uploaded file into the "public/data" directory. You can call the helper function content_type to know the media type of the uploaded file. Here File is a ruby object and join is a helper function that will concatenate the directory name along with the file name and will return the full file path. Next, to open a file in write mode, we are using the open helper function provided by the File object. Further, we are reading data from the passed data file and writing into output file. Creating Controller. Now, let's create a controller for our upload project − Now, we will create two controller functions. The first function index will call a view file to take user input, and the second function uploadFile takes file information from the user and passes it to the 'DataFile' model. We set the upload directory to the 'uploads' directory we created earlier "directory = 'data'". Here, we are calling the function defined in the model file. The render function is being used to redirect to view file as well as to display a message. Creating View. Finally, we will create a view file uploadfile.rhtml, which we have mentioned in the controller. Populate this file with the following code − Here everything is same what we have explained in the earlier chapters. The only new tag is file_field , which will create a button to select a file from user's computer. By setting the multipart parameter to true, you ensure that your action properly passes along the binary data from the file. Here, an important point to note is that we have assigned "uploadFile" as the method name in :action , which will be called when you click the Upload button. It will show you a screen as follows − Now, you select a file and upload it. This file will be uploaded into app/public/data directory with the actual file name and a message will be displayed saying that "File has been uploaded successfully". NOTE − If a file with the same name already exists in your output directory, then it will be overwritten. Files Uploaded from Internet Explorer. Internet Explorer includes the entire path of a file in the filename sent, so the original_filename routine will return something like − Instead of just − This is easily handled by File.basename , which strips out everything before the filename. Deleting an Existing File. If you want to delete any existing file, it is quite simple. All that you need to do is write the following code − For a complete detail on File object, you need to go through our Ruby Reference Manual . Ruby on Rails - File Uploading. You may have a requirement in which you want your site visitors to upload a file on your server. Rails makes it very easy to handle this requirement. Now we will proceed with a simple and small Rails project. As usual, let's start off with a new Rails application called testfile . Let's create the basic structure of the application by using simple rails command. Before starting application development, we should install gem files as shown below − Open up your gemfile and add the following two gems at the bottom as shown in the following image − After adding gems in the gem file, we need to run the following command on the console − Creating the Model. We need to create a model with two strings as name and attachment as shown below − We need to create the database migration as shown below − We need to generate the controller as shown below − Great! Now we have the basic structure set up. Now we need to create an uploader. An Uploader came from carrierwave gem and it tells to carrierwave how to handle the files. In short, it contained all file processing functionalities. Run the command to create an uploader as shown below. Now open the resume model and call the uploader as shown below. Resume model has placed at app/models/resume.rb − Before working on controller, we need to modify our config/routes.db as shown below − Lets us edit the controller as shown below. Let's add bootstrap implementation in css file.css file could be in app/assets/stylesheets/resumes.css.scss. Now open up app/views/layouts/application.html.erb and add codes as shown below − Now we need to set up index views as shown below − Now, lets edit new.html.erb and add our form code. Now start the server and visit http://localhost:3000. It will produce a screen similar to as follows − One last thing we need to do is filter the list of allowed filetypes. For that we need add simple code as shown below at app/uploaders/attachment_uploader.rb. Now start the server and visit http://localhost:3000. Now input a wrong format; it will generate a wrong message as shown below − For a complete detail on File object, you need to go through the Ruby Reference Manual . Rails download file from path. A blob is a record that contains the metadata about a file and a key for where that file resides on the service. Blobs can be created in two ways: Ahead of the file being uploaded server-side to the service, via create_and_upload! . A rewindable io with the file contents must be available at the server for this operation. Ahead of the file being directly uploaded client-side to the service, via create_before_direct_upload! . The first option doesn't require any client-side JavaScript integration, and can be used by any other back-end service that deals with files. The second option is faster, since you're not using your own server as a staging point for uploads, and can work with deployments like Heroku that do not provide large amounts of disk space. Blobs are intended to be immutable in as-so-far as their reference to a specific file goes. You're allowed to update a blob's metadata on a subsequent pass, but you should not update the key or change the uploaded file. If you need to create a derivative or otherwise change the blob, simply create a new blob and purge the old one. Rails download file from path. Gemfile - A format for describing gem dependencies for Ruby programs. Place the Gemfile in the root of the directory containing the associated code. For instance, in a Rails application, place the Gemfile in the same directory as the Rakefile . Syntax. A Gemfile is evaluated as Ruby code, in a context which makes available a number of methods used to describe the gem requirements. Global Sources. At the top of the Gemfile , add a line for the Rubygems source that contains the gems listed in the Gemfile . It is possible, but not recommended as of Bundler 1.7, to add multiple global source lines. Each of these source s MUST be a valid Rubygems repository. Sources are checked for gems following the heuristics described in SOURCE PRIORITY. If a gem is found in more than one global source, Bundler will print a warning after installing the gem indicating which source was used, and listing the other sources where the gem is available. A specific source can be selected for gems that need to use a non-standard repository, suppressing this warning, by using the :source option or a source block. Credentials. Some gem sources require a username and password. Use bundle config(1) to set the username and password for any of the sources that need it. The command must be run once on each computer that will install the Gemfile, but this keeps the credentials from being stored in plain text in version control. For some sources, like a company Gemfury account, it may be easier to include the credentials in the Gemfile as part of the source URL. Credentials in the source URL will take precedence over credentials set using config . If your application requires a specific Ruby version or engine, specify your requirements using the ruby method, with the following arguments. All parameters are OPTIONAL unless otherwise specified. Version (required) The version of Ruby that your application requires. If your application requires an alternate Ruby engine, such as JRuby, Rubinius or TruffleRuby, this should be the Ruby version that the engine is compatible with. Engine. Each application may specify a Ruby engine. If an engine is specified, an engine version must also be specified. What exactly is an Engine? - A Ruby engine is an implementation of the Ruby language.