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 %>

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.

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

If the optional suffix parameter is given, it will be inserted into the filename before the extension. So if the uploaded file is name "vancouver.jpg" and you have the following code in your view

   <%= url_for_file_column("entry", "image", "thumb") %>

the resulting URL’s would point to a file "vancouver-thumb.jpg". This can be used to access different versions of a file as produced by FileColumn::Magick, for example.

Note that the object has to be stored in an instance variable. So if object_name is "entry" your object has to be stored in @entry.