Question

所以我正在使用rails和google云数据存储的web应用程序。我在编写网络应用程序方面相对较新。我遇到的大多数错误都来自于尝试将数据存储与rails MVC模型集成。对于更多上下文，我的大部分代码都基于数据存储信息页面上的Google Datastore Bookshelf教程。 https://cloud.google.com/ruby/getting-started/using-cloud-datastore

最近，当我尝试将帖子保存到数据存储区数据库时，我遇到了PostsController #creore中的NameError。我似乎无法找到这个问题的原因所以希望有人可以成为我新的眼睛或提供一些见解。

此外，如果您知道我可以使用数据存储区和rails找到有用文档的任何地方。那将是值得赞赏的

所以这是我的post_controller.rb文件

class PostsController < ApplicationController

  PER_PAGE = 10

  def index
     @post, @cursor = Post.query limit: PER_PAGE, cursor: params[:cursor]
  end

  def new
    @post = Post.new
  end

  def create
    @post = Post.new post_params

    if @post.save
      flash[:success] = "Posted"
      redirect_to posts_path(@post)
    else
      render :new
      end
  end

  def edit
    @post = Post.find(params[:id])
  end

  def update
    @post = Post.find(params[:id])

    if @post.update(post_params)
      redirect_to @post
    else
      render 'edit'
      end
  end

  def show
    @post = Post.find(params[:id])
  end

  def destroy
    @post = Post.find(params[:id])
    @post.destroy

    redirect_to posts_path
  end

  private
    def post_params
        params.require(:post).permit(:title, :body)
      end

end

这是post post_rb的模型

require "google/cloud/datastore"

class Post
    include ActiveModel::Model
    attr_accessor :title, :body

    # Return a Google::Cloud::Datastore::Dataset for the configured dataset.
     # The dataset is used to create, read, update, and delete entity objects.
        def self.dataset
        @dataset ||= Google::Cloud::Datastore.new(
        project: Rails.application.config.
                     database_configuration[Rails.env]["dataset_id"]
    )


end

# Query Book entities from Cloud Datastore.
#
# returns an array of Book query results and a cursor
# that can be used to query for additional results.
def self.query options = {}
  query = Google::Cloud::Datastore::Query.new
  query.kind "Post"
  query.limit options[:limit]   if options[:limit]
  query.cursor options[:cursor] if options[:cursor]

  results = dataset.run query
  posts   = results.map {|entity| Post.from_entity entity }

  if options[:limit] && results.size == options[:limit]
    next_cursor = results.cursor
  end

  return posts, next_cursor
end

  # [START from_entity]
def self.from_entity entity
  post = Post.new
  post.id = entity.key.id
  entity.properties.to_hash.each do |name, value|
    post.send "#{name}=", value if post.respond_to? "#{name}="
  end
  post
end
 # [END from_entity]

  # [START find]
  # Lookup Book by ID.  Returns Book or nil.
  def self.find id
    query    = Google::Cloud::Datastore::Key.new "Post", id.to_i
    entities = dataset.lookup query

    from_entity entities.first if entities.any?
  end
  # [END find]


 # [START validations]
  # Add Active Model validation support to Book class.
  include ActiveModel::Validations

  validates :title, presence: true

  # [END validations]

  # Save the book to Datastore.
# @return true if valid and saved successfully, otherwise false.
def save
  if valid?
    entity = to_entity
    Post.dataset.save entity
    self.id = entity.key.id
    true
  else
    false
  end
end

end

这是我用来调用数据存储区中的save方法的new.html.erb文件

<h1>Create Post</h1>
<%= form_for @post do |f| %>
    <% if @post.errors.any? %>
        <% @post.errors.full_messages.each do |msg| %>
            <div class="alert alert danger"><%= msg %></div>
        <% end %>
    <% end %>
    <div class="form-group">
        <%= f.label:title %><br>
        <%= f.text_field(:title, {:class => 'form-control'}) %>
    </div>
    <div class="form-group">
        <%= f.label:body %><br>
        <%= f.text_area(:body, {:class => 'form-control'}) %>
    </div>
    <p>
    <%= f.submit({:class => 'btn btn-primary'}) %>
    </p>
<% end %>

这是我的routes.rb文件

Rails.application.routes.draw do
  get 'auth/:provider/callback', to: 'sessions#create'
  get 'auth/failure', to: redirect('/')
  get 'signout', to: 'sessions#destroy', as: 'signout'

  resources :sessions, only: [:create, :destroy]
  resource :main, only: [:show]

  resources :posts

  root to: 'posts#index', as: "home"


  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
end

编辑：忘记包含错误消息日志

NameError (undefined local variable or method `to_entity' for #<Post:0x65b0d70>
Did you mean?  to_key):

app/models/post.rb:72:in `save'
app/controllers/posts_controller.rb:16:in `create'

注意：create.html.erb为空，因此我选择不包含它

Answer 1

好的，看起来你错过了to_entity方法。尝试为您的帖子模型添加类似的内容。我稍微修改了Book文档示例here中的代码。您将需要阅读整个文件，以查看所有代码的Book模型。

def to_entity
  entity                 = Google::Cloud::Datastore::Entity.new
  entity.key             = Google::Cloud::Datastore::Key.new "Post", id
  entity["title"]        = title
  entity["body"]         = body
  entity
end

PostsController中的NameError #create

1 个答案: