Rails 6 and multiple uploads

Active Storage is awesome for uploading images, but handling has_many_attached needs some additional stuff if you want be able to add and remove specific images.

This is how I setup multiple uploads so files can be added and deleted without re-uploading the files.

Model

The model is pretty easy... Probably you already have something like this:

...

  has_many_attached :images

Controller

Next we need to handle params a bit differently for updates vs creates. Also need to allow a remove_image_ids params array so we know which images/files to delete.

In the controller we need a new params method that removes the remove_image_ids and images keys for updates. Don't forget to update the call on the @product.update method call.

I also added two more methods to return the ids and images.

If the update is successful, then I remove any images that should be removed and add newly uploaded images to the current collection of images.

def update
  respond_to do |format|
    if @product.update(product_update_params) # CHANGE THIS
      remove_ids = Array.wrap(remove_image_ids_params)
      remove_ids.each do |id|
        image = @product.images.where(id: id).first
        image&.purge_later
      end

      @product.images.attach(images_params) if images_params.present?

      format.html { redirect_to @product, notice: "Product was successfully updated." }
      format.json { render :show, status: :ok, location: @product }
    else
      format.html { render :edit }
      format.json { render json: @product.errors, status: :unprocessable_entity }
    end
  end
end

...

private

def product_params
  params.require(:product).permit(:name, :description, :url,
    :brand_id, :external_id, :price, :feat_image, remove_image_ids: [], images: [])
end

def product_update_params
  product_params.except(:remove_image_ids, :images)
end

def remove_image_ids_params
  product_params[:remove_image_ids]
end

def images_params
  product_params[:images]
end

Views

In the form we need to show what images are currently uploaded. We'll use StimulusJS to select the images to be removed and set a hidden id value for the selected images. The data- attributes are for StimulusJS.

/ app/views/products/_form.html.slim

.form-group
  .existing.d-flex.flex-wrap.py-4

    - @product.images.each do |image|
      .image.mb-2 data-controller="image-manager" data-image-manager-id=image.id
        button class="border-info m-2 p-0" style="border-width: 3px" data-action="image-manager#toggle" data-target="image-manager.button"
          = image_tag image.variant(combine_options: {resize: "150x150", gravity: "Center", extent: "150x150"}), class: ""
        = hidden_field_tag "product[remove_image_ids][]", nil, data: { target: "image-manager.input" }

    - if @product.images.attached?
      span class="hint w-100"
        | Select images you want to remove

  = f.label :images, "Add Images", class: "form-control-label"
  = f.file_field :images, multiple: true, class: "form-control"

StimulusJS

This controller will attach to each image on the form and toggle it's removal status on click. This assumes you have StimulusJS setup and working already.

// app/javascript/controllers/image_manager_controller.js

import { Controller } from 'stimulus'

export default class extends Controller {
  static targets = [ "input", "button" ]

  toggle(e) {
    e.preventDefault()

    const id = this.data.get("id")

    this.buttonTarget.classList.remove("border-red")
    this.buttonTarget.classList.remove("border-info")

    if (this.inputTarget.value === id) {
      this.inputTarget.value = null
      this.buttonTarget.classList.add("border-info")
    } else {
      this.inputTarget.value = id
      this.buttonTarget.classList.add("border-red")
    }
  }
}

That's it! Now we can add multiple images without overwriting any already uploaded images. And we can remove specific uploaded images, one by one.