我正在Rails创建我的第一个应用程序，一个电子商务，并希望将评论与产品相关联，我创建了所有必要的结构，我有用户模型，产品和评论，我想我做了一切是的，但是当我去渲染表单以插入评论时，我收到了这个错误：
表单中的第一个参数不能包含nil或为空
else
object = record.is_a?(Array) ? record.last : record
raise ArgumentError, "First argument in form cannot contain nil or be empty" unless object
object_name = options[:as] || model_name_from_record_or_class(object).param_key
apply_form_for_options!(record, object, options)
end
呈现表单的视图是
<%= form_for(@comment, html: {multipart: true}) do |f| %>
<%= render 'shared/error_messages', object: f.object %>
<div class="field">
<%= f.text_area :content, placeholder: "Compose new comment..." %>
</div>
<%= f.submit "Post", class: "btn btn-primary" %>
<span class="picture">
<%= f.file_field :picture, accept: 'image/jpeg,image/gif,image/png' %>
</span>
<% end %>
<script type="text/javascript">
$('#comment_picture').bind('change', function() {
size_in_megabytes = this.files[0].size/1024/1024;
if (size_in_megabytes > 8) {
alert('Maximum file size is 8MB. Please choose a smaller file.');
}
});
评论控制器
class CommentsController < ApplicationController
before_action :logged_in_user, only: [:create, :destroy, :show]
before_action :correct_user, only: :destroy
def show
@comment = Comment.find(params[:id])
end
def create
@comment = current_user.comment.build(comment_params)
if @comment.save
flash[:success] = "Comment created!"
redirect_to store_url
else
@feed_items = []
render 'static_pages/home'
end
end
def destroy
@comment.destroy
flash[:success] = "Comment deleted"
redirect_to request.referrer || store_url
end
private
def comment_params
params.require(:comment).permit(:content, :picture)
end
def correct_user
@comment = current_user.comments.find_by(id: params[:id])
redirect_to store_url if @comment.nil?
end
end
展示产品控制器
class ProductsController < ApplicationController
before_action :set_product, only: [:show, :edit, :update, :destroy]
# GET /products
# GET /products.json
def index
@products = Product.paginate(page: params[:page])
end
# GET /products/1
# GET /products/1.json
def show
@product = Product.find(params[:id])
@comments = current_user.comments.build if logged_in?
@comments = @product.comments.paginate(page: params[:page])
@rating = Rating.where(product_id: @product.id, user_id: @current_user.id).first
unless @rating
@rating = Rating.create(product_id: @product.id, user_id: @current_user.id, score: 0)
end
end
用户控制器
class UsersController < ApplicationController
before_action :logged_in_user, only: [:index, :edit, :update, :destroy]
before_action :correct_user, only: [:edit, :update]
before_action :admin_user, only: :destroy
def index
@users = User.where(activated: true).paginate(page: params[:page])
end
def show
@user = User.find(params[:id])
@comments = @user.comments.paginate(page: params[:page])
end
def new
@user = User.new
end
def create
@user = User.new(user_params)
if @user.save
@user.send_activation_email
flash[:info] = "Please check your email to activate your account."
redirect_to store_url
else
render 'new'
end
end
def update
if @user.update_attributes(user_params)
flash[:success] = "Profile updated"
redirect_to @user
else
render 'edit'
end
end
def edit
@user = User.find(params[:id])
end
def destroy
User.find(params[:id]).destroy
flash[:success] = "User deleted"
redirect_to users_url
end
private
def user_params
params.require(:user).permit(:name, :email, :password,
:password_confirmation)
end
# Confirms the correct user.
def correct_user
@user = User.find(params[:id])
redirect_to(store_url) unless current_user?(@user)
end
# Confirms an admin user.
def admin_user
redirect_to(store_url) unless current_user.admin?
end
end
如果有必要的话，我可以发布你也相信模特，感谢所有帮助我的人。
日志文件：
Started GET "/en/products/4" for 127.0.0.1 at 2015-07-12 20:30:01 +0200
Processing by ProductsController#show as HTML
Parameters: {"locale"=>"en", "id"=>"4"}
Product Load (0.2ms) SELECT "products".* FROM "products" WHERE "products"."id" = ? LIMIT 1 [["id", 4]]
CACHE (0.0ms) SELECT "products".* FROM "products" WHERE "products"."id" = ? LIMIT 1 [["id", "4"]]
User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
Rating Load (0.2ms) SELECT "ratings".* FROM "ratings" WHERE "ratings"."product_id" = ? AND "ratings"."user_id" = ? ORDER BY "ratings"."id" ASC LIMIT 1 [["product_id", 4], ["user_id", 1]]
(0.2ms) SELECT COUNT(*) FROM "ratings" WHERE "ratings"."product_id" = ? [["product_id", 4]]
(0.2ms) SELECT COUNT(*) FROM "comments" WHERE "comments"."user_id" = ? [["user_id", 1]]
Rendered shared/_user_info.html.erb (3.0ms)
Rendered shared/_error_messages.html.erb (0.1ms)
(0.2ms) SELECT SUM("ratings"."score") FROM "ratings" WHERE "ratings"."product_id" = ? [["product_id", 4]]
CACHE (0.0ms) SELECT COUNT(*) FROM "ratings" WHERE "ratings"."product_id" = ? [["product_id", 4]]
Rendered shared/_comment_form.html.erb (7.6ms)
CACHE (0.0ms) SELECT SUM("ratings"."score") FROM "ratings" WHERE "ratings"."product_id" = ? [["product_id", 4]]
CACHE (0.0ms) SELECT COUNT(*) FROM "ratings" WHERE "ratings"."product_id" = ? [["product_id", 4]]
Rendered products/show.html.erb within layouts/application (24.3ms)
Rendered layouts/_header.html.erb (5.9ms)
Rendered layouts/_footer.html.erb (1.1ms)
Completed 200 OK in 205ms (Views: 197.7ms | ActiveRecord: 1.1ms)
Started POST "/comments?locale=en" for 127.0.0.1 at 2015-07-12 20:30:11 +0200
Processing by StaticPagesController#home as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"1sIh3jNERiiitmbyHQaQpAomMIgjXKkBVA/RqsIYDhYkD73gFOeMKyYYtmjSr9mu0ngyKSephYmfJhvvlKMigg==", "comment"=>{"content"=>"Hello! "}, "commit"=>"Post", "locale"=>"comments"}
comments translation not available
Rendered static_pages/home.html.erb within layouts/application (70.2ms)
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]
Rendered layouts/_header.html.erb (4.4ms)
Rendered layouts/_footer.html.erb (0.6ms)
Completed 200 OK in 249ms (Views: 246.7ms | ActiveRecord: 0.2ms)