ruby-on-rails – 为什么我的关联类型不匹配？

基本上,我已经创建了一个产品表单并添加了一个“供应商”选择字段,该字段找到了我的所有供应商,但现在当我尝试更新当前产品或创建新产品时,我收到以下错误：

ActiveRecord::AssociationTypeMismatch in ProductsController#create
Supplier(#2178099880) expected,got String(#2148287480)

我理解错误告诉我的是什么,但我不明白为什么.我也以同样的方式创建了产品类别的关联,工作正常！

此外,如果我添加验证以验证供应商的存在,即使选择了供应商,我也会收到“供应商不能为空”的错误.

真的很感激一些帮助！

在我的_form.html中,我有：

<%= f.label :supplier %>
<%= f.select(:supplier,Supplier.find(:all).collect {|c| [ c.name,c.id ]},:include_blank => true) %>

产品控制器：

class ProductsController < ApplicationController
  # GET /products
  # GET /products.xml
  def index
    @products = Product.all

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @products }
    end
  end

  # GET /products/1
  # GET /products/1.xml
  def show
    @product = Product.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @product }
    end
  end

  # GET /products/new
  # GET /products/new.xml
  def new
    @product = Product.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @product }
    end
  end

  # GET /products/1/edit
  def edit
    @product = Product.find(params[:id])
  end

  # POST /products
  # POST /products.xml
  def create
    @product = Product.new(params[:product])

    respond_to do |format|
      if @product.save
        format.html { redirect_to(@product,:notice => 'Product was successfully created.') }
        format.xml  { render :xml => @product,:status => :created,:location => @product }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @product.errors,:status => :unprocessable_entity }
      end
    end
  end

  # PUT /products/1
  # PUT /products/1.xml
  def update
    @product = Product.find(params[:id])

    respond_to do |format|
      if @product.update_attributes(params[:product])
        format.html { redirect_to(@product,:notice => 'Product was successfully updated.') }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @product.errors,:status => :unprocessable_entity }
      end
    end
  end

  # DELETE /products/1
  # DELETE /products/1.xml
  def destroy
    @product = Product.find(params[:id])
    @product.destroy

    respond_to do |format|
      format.html { redirect_to(products_url) }
      format.xml  { head :ok }
    end
  end
end

产品型号：

class Product < ActiveRecord::Base

  belongs_to :supplier
  belongs_to :categories
  default_scope :order => 'product_number'

  validates_presence_of :product_name,:product_number,:category,:opening_order,:initial_cover,:country_of_origin,:supplier

  validates_uniqueness_of :product_number

  # Paperclip

  has_attached_file :image,:styles => { :medium => "300x300>",:thumb => "100x100>" }
end