在链接中将参数传递给控制器​​的“轨道方式”是什么？

Question

I'm trying to pass a variable from my view to my controller in a link_to. My link_to:

<%= link_to "Download CSV", vendor_skus_path(format: "csv") %>

I would like to pass an extra filter parameter, but this parameter is set in the view and is not part of a form. How can I get this parameter to my controller so that I could use it in my model? How I build the extra filter parameter:

<%= select_tag "vendor-select", options_from_collection_for_select(@vendors, "id", "name"), include_blank: true, class:"vendor-select form-control" %> 

In my vendor_skus#index controller I do this:

respond_to do |format|
  format.html
  format.csv { send_data @vendor_skus.to_csv }
end   

What I would like is something like below, so that I can use the extra parameter to filter the rows that are exported.

respond_to do |format|
  format.html
  format.csv { send_data @vendor_skus.to_csv, vendor_id }
end  

Answer 1

A bit late to the party, but hoping this helps someone that may come across something similar. I just came across a similar issue. I needed to pass additional filtering parameters to export associated data specific to the record being viewed on the show page.

You can pass parameters after the "format: 'CSV'" in your link_to path.

The following steps should help you achieve your goal. Please note that I made assumptions about your setup. I'm assuming you have a VENDOR model and each VENDOR has_many :vendor_skus. So your 2nd associated model would be VENDOR_SKU which belongs_to :vendor.

1. Create a link which passes parameters that can be used for filtering.

<%= link_to "Download CSV", vendorskus_export_path(format: "csv", :id => @vendor.id) %> 

The above link_to would look something like this:

/ventorskus/export.csv?id=3

2. Create a GET route for the link (/config/routes.rb)

get '/vendorskus/export', to: 'vendor_skus#export'

3. Create "export" in vendor_skus controller

def export
    require 'csv'
    vendor = vendor.find(params[:id])
    @export_metadata = vendor.vendor_skus.all
    respond_to do |format|
      format.html
      format.csv { send_data @export_metadata.to_csv, filename: "Vendor-#{vendor.id}_SKUS_#{Date.today}.csv" }
    end
end

4. Configuring your VENDOR_SKU model (/model/vendor_sku.rb)

class VendorSkus < ApplicationRecord
  #-- Associations --#
  belongs_to :vendor

  #-- Validation Code Here --#
  #-- Scopes Code Here --#
  #-- Custom Code Here --#

  #------------------------------------------------------#
  private
  def self.to_csv
     CSV.generate do |csv|
       csv << column_names
       all.each do |result|
        csv << result.attributes.values_at(*column_names)
       end
     end
  end