Module: FileColumnHelper

Included in:
ActionView::Base
Defined in:
lib/file_column_helper.rb

Overview

This module contains helper methods for displaying and uploading files for attributes created by FileColumn‘s file_column method. It will be automatically included into ActionView::Base, thereby making this module’s methods available in all your views.

Instance Method Summary collapse

Instance Method Details

#file_column_field(object, method, options = {}) ⇒ Object

Use this helper to create an upload field for a file_column attribute. This will generate an additional hidden field to keep uploaded files during form-redisplays. For example, when called with

<%= file_column_field("entry", "image") %>

the following HTML will be generated (assuming the form is redisplayed and something has already been uploaded):

<input type="hidden" name="entry[image_temp]" value="..." />
<input type="file" name="entry[image]" />

You can use the option argument to pass additional options to the file-field tag.

Be sure to set the enclosing form’s encoding to ‘multipart/form-data’, by using something like this:

<%= form_tag {:action => "create", ...}, :multipart => true %>



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# File 'lib/file_column_helper.rb', line 25

def file_column_field(object, method, options={})
  result = ActionView::Helpers::InstanceTag.new(object.dup, method.to_s+"_temp", self).to_input_field_tag("hidden", {})
  result << ActionView::Helpers::InstanceTag.new(object.dup, method, self).to_input_field_tag("file", options)
end

#url_for_file_column(object, method, options = nil) ⇒ Object

Creates an URL where an uploaded file can be accessed. When called for an Entry object with id 42 (stored in @entry) like this

<%= url_for_file_column(@entry, "image")

the following URL will be produced, assuming the file “test.png” has been stored in the “image”-column of an Entry object stored in @entry:

/entry/image/42/test.png

This will produce a valid URL even for temporary uploaded files, e.g. files where the object they are belonging to has not been saved in the database yet.

The URL produces, although starting with a slash, will be relative to your app’s root. If you pass it to one rails’ image_tag helper, rails will properly convert it to an absolute URL. However, this will not be the case, if you create a link with the link_to helper. In this case, you can pass :absolute => true to options, which will make sure, the generated URL is absolute on your server. Examples:

<%= image_tag url_for_file_column(@entry, "image") %>
<%= link_to "Download", url_for_file_column(@entry, "image", :absolute => true) %>

If there is currently no uploaded file stored in the object’s column this method will return nil.



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# File 'lib/file_column_helper.rb', line 56

def url_for_file_column(object, method, options=nil)
  case object
  when String, Symbol
    object = instance_variable_get("@#{object.to_s}")
  end

  # parse options
  subdir = nil
  absolute = false
  if options
    case options
    when Hash
      subdir = options[:subdir]
      absolute = options[:absolute]
    when String, Symbol
      subdir = options
    end
  end
  
  relative_path = object.send("#{method}_relative_path", subdir)
  return nil unless relative_path

  url = ""
  url << ActionController::Base.relative_url_root.to_s if absolute
  url << "/"
  url << object.send("#{method}_options")[:base_url] << "/"
  url << relative_path
end

#url_for_image_column(object, method, options = nil) ⇒ Object

Same as url_for_file_colum but allows you to access different versions of the image that have been processed by RMagick.

If your options parameter is non-nil this will access a different version of an image that will be produced by RMagick. You can use the following types for options:

  • a :symbol will select a version defined in the model via FileColumn::Magick’s :versions feature.

  • a geometry_string will dynamically create an image resized as specified by geometry_string. The image will be stored so that it does not have to be recomputed the next time the same version string is used.

  • some_hash will dynamically create an image that is created according to the options in some_hash. This accepts exactly the same options as Magick’s version feature.

The version produced by RMagick will be stored in a special sub-directory. The directory’s name will be derived from the options you specified (via a hash function) but if you want to set it yourself, you can use the :name => name option.

Examples:

<%= url_for_image_column @entry, "image", "640x480" %>

will produce an URL like this

/entry/image/42/bdn19n/filename.jpg
# "640x480".hash.abs.to_s(36) == "bdn19n"

and

<%= url_for_image_column @entry, "image", 
   :size => "50x50", :crop => "1:1", :name => "thumb" %>

will produce something like this:

/entry/image/42/thumb/filename.jpg

Hint: If you are using the same geometry string / options hash multiple times, you should define it in a helper to stay with DRY. Another option is to define it in the model via FileColumn::Magick’s :versions feature and then refer to it via a symbol.

The URL produced by this method is relative to your application’s root URL, although it will start with a slash. If you pass this URL to rails’ image_tag helper, it will be converted to an absolute URL automatically. If there is currently no image uploaded, or there is a problem while loading the image this method will return nil.



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# File 'lib/file_column_helper.rb', line 135

def url_for_image_column(object, method, options=nil)
  case object
  when String, Symbol
    object = instance_variable_get("@#{object.to_s}")
  end
  subdir = nil
  if options
    subdir = object.send("#{method}_state").create_magick_version_if_needed(options)
  end
  if subdir.nil?
    nil
  else
    url_for_file_column(object, method, subdir)
  end
end