How to write to a file in Ruby on Rails

By: Pasan on 4:59 PM

This is a simple and easy way to write to a file in Ruby on Rails.

------------------------------------------------
# The content you are going to write to the file 
your_text = "Hello world... !"
  
directory = "public/files"
file_name = "your file name.txt"
 
# create the file path
path = File.join(directory, file_name)
 
# write the file
File.open(path, "w") { |f| f.write(your_text)  
------------------------------------------------

If you are writing a binary file.. for example a pdf file from a file upload use 'wb' instead of 'w'

------------------------------------------------
file_content # this will be in binary format for a pdf file. 

directory = "public/files"
file_name = "your_pdf_file.pdf"
 
# create the file path
path = File.join(directory, file_name)  
# write the file
File.open(path, "wb") { |f| f.write(file_content)  
------------------------------------------------

Here is a sample view file with a form to upload a file. Remember that you have to set 'multipart' option to true to enable file uploads:

------------------------------------------------
<% form_for(upload, :url => {:action => 'create'}, :html => {:multipart => true}) do |f| %>  
    Document tile
   <%= f.text_field :title %>
  
    Author's first name
    <%= f.text_field :author_first %>
  
    Author's last name
    <%= f.text_field :author_last %>
    
    Nicta email address
    <%= f.text_field :email %>
   
   Upload
    <%= f.file_field :datafile %>
  
    <%= f.submit "Create", 
:onclick => "document.getElementById('black_cover').style.display = 'block';" %>  

<% end %>
------------------------------------------------

Below is the controller 'create' action that gets called upon the form submit. The saveFile method in model is the one that actually does the work. The controller simply passes the uploaded file content (:upload) to the saveFile() funciton in the model

------------------------------------------------
 def create
    upload = params[:upload]
   
    # Model will save the file if it's valid
    success, filename = Upload.saveFile(upload)
   
    if (success)
      post = Upload.new do |u|
        u.title = upload['title']
        u.author_first = upload['first_name']
        u.author_last = upload['last_name']
        u.email = upload['email']
        u.filename = filename
      end
    ... 
    ..
    .
------------------------------------------------

Finally, here is the saveFile() function from the model

------------------------------------------------
def self.saveFile(upload)
    if upload['datafile'] == ""
       return [false,  "Upload failed: No document selected for the upload!"]
    end
    
    name =  upload['datafile'].original_filename || nil
    file_type = upload['datafile'].content_type || nil
    file_size = upload['datafile'].size || nil
    
    if name.nil?
      return [false,  "Upload failed: Invalid document name!"]
    end
    
    # check file-type
    if file_type != 'application/pdf'
      return [false,  "Upload failed: File is not a pdf!"]
    end
    
    # check file-size File.     if file_size < 5000
      return [false, "File size was: #{file_size}. Document has to be at least 5KB"] 
    else if file_size > (20*1000*1000) 
      return [false, "File size was: #{file_size}. Document has to be less than xxMB"]
    end
    end
  
    directory = "public/uploads"
    # create the file path
    path = File.join(directory, name)
    # write the file
    File.open(path, "wb") { |f| f.write(upload['datafile'].read) }
    
    return [true, name]
  end 
------------------------------------------------

That's it.

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Give your HTML Tables the Excel Spreadsheet look

By: Pasan on 1:27 PM

This is to give your table the cool spreadsheet look (if you want it!). Sometimes you create tables, you may find that there are gaps between cell borders making the borders look quite thick.

So if you aim is to make your html table look similar to an excel worksheet, you need to make those borders smoother.

As it turns out you can achieve this simply by adding one more CSS line into your CSS code.

You do use a separate CSS section/file right? Don't stick to using inline CSS for everything as it gets pretty messy eventually and you forget what you did. When you separate the CSS, your code looks great and it's easier for anyone to go through and understand your code.

Here is the single line you need to add to your CSS:
border-collapse:collapse;

So add this line to the section where you are formatting your table. Like this:

table{
... your other css lines ..
..
border-collapse:collapse;
}

Then to format the border color and thickness etc:

td {
padding: 7px;
border: 1px solid #ccc;
}

That's all. You'll have a nice spreadsheet like table.

Tip:
Check out this website: http://www.somacon.com/p141.php. It gives you a nice interface to easily try out many different CSS styles on tables.

Sources:
Main: http://www.webmasterworld.com/css/3065746.htm

Others:
http://www.w3schools.com/Css/pr_tab_border-collapse.asp
http://www.w3schools.com/css/pr_tab_border-spacing.asp

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