Question

我在使用has_many时遇到以下问题：通过collection_select进行多选中的多对多关系：multiple =＆gt;真正。我有供应商提供许多成分，可由许多供应商提供。看看：

成分模型：

class Ingredient < ActiveRecord::Base
  has_many :ingredient_suppliers
  accepts_nested_attributes_for :ingredient_suppliers, :allow_destroy => true

  has_many :suppliers, :through => :ingredient_suppliers
end

供应商模式：

class Supplier < ActiveRecord::Base
  has_many :ingredient_suppliers
  has_many :ingredients, :through => :ingredient_suppliers
end

关系实体：

class IngredientSupplier < ActiveRecord::Base
  belongs_to :ingredient
  belongs_to :supplier
end

这是表格。请注意，如果没有指定：name：

，我无法使其工作

<%= form_for(@ingredient) do |f| %>
 <%= f.fields_for :suppliers do |supplier_fields| %>
      <%= supplier_fields.collection_select (:supplier_ids, 
            Supplier.all(:order=>"name ASC"), 
            :id, :name, 
            {:selected => @ingredient.supplier_ids, 
             :include_blank => true}, 
            {:multiple => true, 
              :name => 'ingredient[supplier_ids]'}) %>
  <% end %>
<% end %>

如果我删除：name，则会收到以下错误消息：

Supplier(#-617951108) expected, got Array(#-608411888)

Request

Parameters:

{"commit"=>"Anlegen",
 "authenticity_token"=>"MuEYtngwThharmM1KaAbH8JD3bScXiDwj0ALMytxl7U=",
 "_method"=>"put",
 "utf8"=>"✓",
 "id"=>"1",
 "ingredient"=>{"name"=>"Ingredient 1",
 "nr"=>"00100",
 "unit"=>"kg",
 "mol_per_unit"=>"2000,
00000",
 "description"=>"",
 "suppliers"=>{"supplier_ids"=>["1",
 "2"]}}}

现在的问题是，PUT参数只包含一个supplier_id而不是supplier_id数组：

"ingredient"=>{"name"=>"Rohstoff 3", "nr"=>"00300", "unit"=>"Stk.", "mol_per_unit"=>"0,00000", "description"=>"", "supplier_ids"=>"2"}

Answer 1

我已经解决了问题。在这种情况下，使用fields_for是错误。解决方案是使用collection_select，如下所示：

<%= collection_select(:ingredient, :supplier_ids, 
              Supplier.all(:order=>"name ASC"), 
              :id, :name, {:selected => @ingredient.supplier_ids, :include_blank => true}, {:multiple => true}) %>

Rails has_many：through和collection_select有多个

1 个答案: