Question

对于编程和编程社区来说真的很新，这只是我用ruby进行的第二个项目编程，所以如果我错过了一些明显或做错的话，请原谅。

到目前为止，在这个项目中，我尝试使用Datamapper创建数据库。数据库应包含三个对象：User，Category和Class。用户可以拥有多个类别，并且类别可以属于许多用户，这就是我将这两个对象与UserCategory链接以创建多对多关系的原因。另一个关联是Category和Class之间的关系，即Category对象可以有许多类，但是一个类只能属于一个Category。到目前为止，这是我的数据库：

require "sinatra"
require "data_mapper"
if ENV['RACK_ENV'] == 'production'
  DataMapper.setup(:default, ENV['DATABASE_URL'])
else
  DataMapper.setup(:default, "sqlite:online-arena.db")
end

class User
  include DataMapper::Resource

  property :id,           Serial

  property :username,     String,
    :required => true,
    :unique   => true

  property :password,     BCryptHash, :required => true
  validates_confirmation_of :password

    attr_accessor :password_confirmation
    validates_length_of :password_confirmation, :min => 6

    def valid_password?(unhashed_password)
      self.password == unhashed_password
    end

  property :admin,       Boolean, default: false

    has n, :user_categories
    has n, :categories, through: :user_categories
end

class UserCategory
  include DataMapper::Resource

  property :id,         Serial

  belongs_to    :user
  belongs_to    :category
end

class Category
  include DataMapper::Resource

  property :id,           Serial
  property :title,         String

  has n, :class

  has n, :user_categories
  has n, :users, through: :user_categories
end


class Class
  include DataMapper::Resource

  property :id,           Serial
  property :name,         String
  property :teacher,      String
  property :spots,        Integer

  belongs_to :category
end


DataMapper.finalize
DataMapper.auto_upgrade!

这些是我用于此项目的宝石：

source "https://rubygems.org"

gem "sinatra"
gem "data_mapper"
gem "bcrypt"
gem "rake"

group :development do
  gem "sqlite3"
  gem "dm-sqlite-adapter"

  gem "dotenv"
  gem "rerun"
end

group :production do
  gem "pg"
  gem "dm-postgres-adapter"
end

我使用Cloud9来处理这个项目，到目前为止，我已经＆＃34;捆绑安装 - 没有生产＆＃34;，然后使用＆＃34; ruby online-arena.rb启动它-p $ PORT -o $ IP＆＃34;但它给了我这个错误：

/usr/local/rvm/gems/ruby-2.1.5@rails4/gems/dm-core-1.2.1/lib/dm-core/property/numeric.rb:19:in `fetch': key not found: :precision (KeyError)
    from /usr/local/rvm/gems/ruby-2.1.5@rails4/gems/dm-core-1.2.1/lib/dm-core/property/numeric.rb:19:in `initialize'
    from /usr/local/rvm/gems/ruby-2.1.5@rails4/gems/dm-core-1.2.1/lib/dm-core/property/integer.rb:15:in `initialize'
    from /usr/local/rvm/gems/ruby-2.1.5@rails4/gems/dm-core-1.2.1/lib/dm-core/model/property.rb:55:in `new'
    from /usr/local/rvm/gems/ruby-2.1.5@rails4/gems/dm-core-1.2.1/lib/dm-core/model/property.rb:55:in `property'
    from /usr/local/rvm/gems/ruby-2.1.5@rails4/gems/dm-validations-1.2.0/lib/dm-validations/auto_validate.rb:11:in `property'
    from /home/ubuntu/workspace/models.rb:49:in `<class:Class>'
    from /home/ubuntu/workspace/models.rb:46:in `<top (required)>'
    from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:121:in `require'
    from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:121:in `require'
    from /home/ubuntu/workspace/environment.rb:5:in `<top (required)>'
    from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:121:in `require'
    from /usr/local/rvm/rubies/ruby-2.1.5/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:121:in `require'
    from online-arena.rb:4:in `<main>'

如果没有足够的信息，请访问我的github上的其他文件 https://github.com/FuriousPenguins/Online-Arena

我尝试使用我之前项目的具有类似布局的数据库模型：

https://github.com/kichoy/lunch-reviews/blob/master/models.rb

我能够运行该应用程序。

模型的DataMapper错误（`fetch＆＃39 ;: key not found :: precision（KeyError））

0 个答案: