Working on the backend interface for supporter registrations

app/models/datatable.rb

@@ -0,0 +1,99 @@
+# derived from http://railscasts.com/episodes/340-datatables
+# handles server side multi-column searching and sorting
+
+class Datatable
+  delegate :params, :h, :raw, :link_to, :number_to_currency, to: :@view
+
+  def initialize(klass, view)
+    @klass = klass
+    @view = view
+  end
+
+  def as_json(options = {})
+    {
+        sEcho: params[:sEcho].to_i,
+        iTotalRecords: @klass.count,
+        iTotalDisplayRecords: items.total_entries,
+        aaData: data
+    }
+  end
+
+
+  def data
+    []
+  end
+
+  def columns
+    []
+  end
+
+  private
+
+  def items
+    @items ||= fetch_items
+  end
+
+  def fetch_items
+    items = filtered_list
+    items = selected_columns(items)
+    items = items.order(sort_order)
+    items = items.page(page).per_page(per_page)
+    if params[:sSearch].present?
+      items = items.where(quick_search)
+    end
+    items
+  end
+
+  def filtered_list
+    @klass.scoped
+  end
+
+  def selected_columns items
+    items
+  end
+
+  def quick_search
+    search_for = params[:sSearch].split(' ')
+    terms = {}
+    which_one = -1
+    criteria = search_for.inject([]) do |criteria,atom|
+      which_one += 1
+      terms["search#{which_one}".to_sym] = "%#{atom}%"
+      criteria << "(#{search_cols.map{|col| "#{col} like :search#{which_one}"}.join(' or ')})"
+    end.join(' and ')
+    [criteria, terms]
+  end
+
+  def page
+    params[:iDisplayStart].to_i/per_page + 1
+  end
+
+  def per_page
+    params[:iDisplayLength].to_i > 0 ? params[:iDisplayLength].to_i : 10
+  end
+
+  def sort_order
+    colnum = 0
+    sort_by = []
+    while true
+      break if !sorted?(colnum)
+      sort_by << "#{sort_column(colnum)} #{sort_direction(colnum)}"
+      colnum += 1
+    end
+    sort_by.join(", ")
+  end
+
+  def sorted? index=0
+    !params["iSortCol_#{index}"].nil?
+  end
+
+  def sort_column index=0
+    index = "iSortCol_#{index}"
+    columns[params[index].to_i]
+  end
+
+  def sort_direction index=0
+    index = "sSortDir_#{index}"
+    params[index] == "desc" ? "desc" : "asc"
+  end
+end