On 11 February 2016 at 03:08, Walter Lee Davis <wa...@wdstudio.com> wrote:
> ...
> In order to do this (no matter which file attachment system you choose) you
> will need to refactor your application slightly. You need a model instance
> *per* image uploaded, so the usual way to do this is with a nested form. You
> create a form on a parent object that `has_many` of the image objects. If the
> Listing model is the parent, then you can add an Image model to belong to
> that listing, in a one-to-many relationship. Then you set up the following
> (this is pseudocode, off the top of my head, not guaranteed to work as
> written, but the right idea, IMO):
>
> class Listing < ActiveRecord::Base
> has_many :images
> accepts_nested_attributes_for :images, allow_destroy: true, reject_if:
> :all_blank
> end
>
> class Image < ActiveRecord::Base
> belongs_to :listing
> has_attached_file :image
> end
>
> class ListingsController < ApplicationController
> ... all the usual CRUD actions here
> private
> def listing_params
> params.require(:listing).permit(:name, :description, :price,
> images_attributes: [:id, :image, :_destroy])
> end
> end
>
> And finally, in your form_for @listing, you need to create a very
> particularly named field in order to get this all to work together:
>
> <%= file_field_tag('listing_images_attributes_image', multiple: true, :name
> => "listing[images_attributes][][image]") %>
>
> That last part is ripped out of working code using Paperclip.
>
> Things to note here:
> 1. It's using the file_field_tag generator (long-hand) rather than the
> f.file_field that you may be used to. This is so that the name can be exactly
> what it needs to be to "trick" the accepts_nested_attributes_for helper into
> accepting the attached files.
> 2. The multiple: true thing means that you will need a modern browser to use
> this (HTML5 feature).
> 3. The empty square-brackets in the middle of the name are the "secret sauce"
> that cause the individual files in the multiple file form element to be sent
> as separate files, rather than the last one "winning" or the data being
> concatenated and sent as form post body instead.
> 4. This type of field is only useful on an initial create or upload screen,
> not if you want to edit each of the attached files individually. I would put
> this particular form on the #new screen.
>
> Once you have this working, you will need to make your #edit screen a more
> traditional nested form. Read this for an example and further ideas:
> http://railscasts.com/episodes/196-nested-model-form-revised?view=asciicast
What a great post, thanks Walter. That is going straight into
useful-notes-to-keep-in-case-I-ever-want-to-do-it.
Colin
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