当提供rom-rb属性时，空验证失败。

Question

我正在尝试使用sqlite3来处理rom持久性库。

我运行了以下迁移，其中包括一个NOT NULL约束：

ROM::SQL.migration do
  change do
    create_table :users do
      primary_key :id
      column :name, String, null: false
      column :age, Integer
      column :is_admin, TrueClass
    end
  end
end

这是我的简单app.rb

require 'rom'

rom = ROM.container(:sql, 'sqlite://db/my-db-file.db') do |config|
  class Users < ROM::Relation[:sql]
    schema(infer: true)
  end

  config.relation(:users)
end

users = rom.relations[:users]
puts users.to_a.inspect # => []

create_user = users.command(:create)
create_user.call( name: 'Rob', age: 30, is_admin: true )
puts users.to_a.inspect # never reached

试图运行此脚本会产生以下输出：

Roberts-MacBook-Pro:my-rom-demo Rob$ ruby app.rb 
[]
/Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/statement.rb:108:in `step': SQLite3::ConstraintException: NOT NULL constraint failed: users.name (ROM::SQL::NotNullConstraintError)
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/statement.rb:108:in `block in each'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/statement.rb:107:in `loop'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/statement.rb:107:in `each'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/database.rb:156:in `to_a'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/database.rb:156:in `block in execute'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/database.rb:95:in `prepare'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sqlite3-1.3.13/lib/sqlite3/database.rb:137:in `execute'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/adapters/sqlite.rb:189:in `block (2 levels) in _execute'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/database/logging.rb:38:in `log_connection_yield'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/adapters/sqlite.rb:189:in `block in _execute'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/database/connecting.rb:253:in `block in synchronize'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/connection_pool/threaded.rb:91:in `hold'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/database/connecting.rb:253:in `synchronize'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/adapters/sqlite.rb:180:in `_execute'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/adapters/sqlite.rb:146:in `execute_insert'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/dataset/actions.rb:1099:in `execute_insert'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/sequel-5.11.0/lib/sequel/dataset/actions.rb:399:in `insert'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-sql-2.5.0/lib/rom/sql/relation/writing.rb:39:in `insert'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-sql-2.5.0/lib/rom/sql/commands/create.rb:46:in `block in insert'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-sql-2.5.0/lib/rom/sql/commands/create.rb:46:in `map'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-sql-2.5.0/lib/rom/sql/commands/create.rb:46:in `insert'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-sql-2.5.0/lib/rom/sql/commands/create.rb:31:in `execute'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-core-4.2.1/lib/rom/command.rb:280:in `call'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-sql-2.5.0/lib/rom/sql/commands/error_wrapper.rb:16:in `call'
    from /Rob.rvm/gems/ruby-2.4.0@learn-rails/gems/rom-core-4.2.1/lib/rom/commands/composite.rb:17:in `call'
    from app.rb:15:in `<main>'

当我提供name属性时，它为什么认为它是空的呢？

Answer 1

注意：在测试和学习了ops gem版本之后，修改了我的答案。

您获得NULL CONSTRAINT错误的原因是因为ROM没有为users表加载模式。

当您定义下面的容器时

rom = ROM.container(:sql, 'sqlite://db/my-db-file.db') do |config|
  class Users < ROM::Relation[:sql]
    schema(infer: true)
  end

  config.relation(:users)
end

您定义了两件事，一个绑定到一个名为Users的常量的关系类和一个自动生成的名称相同的关系，但实际上是在ROM容器中注册的。有效地忽略了Users常数关系。之所以这么做很重要，是因为自动生成的关系不会自动从数据库中推断出模式，所以当您将数据写出来时，模式会强制删除所有导致错误的未知键。您要发送到数据库的全部是{}。

要修复错误，只需告诉关系来推断模式-下面可以看到一个例子。

require 'rom'
require 'rom/sql'
require 'sqlite3'

puts "ROM Version #{ROM::Core::VERSION}" # 4.2.1
puts "ROM Version #{ROM::SQL::VERSION}" # 2.5.0
puts "Sequel Version #{Sequel::VERSION}" # 5.11.0
puts "SQLite3 Gem Version #{SQLite3::VERSION}" # 1.3.13

opts = {
  adapter: :sqlite,
  database: 'c:/mydb.db'
}

rom = ROM.container(:sql, opts) do |c|
  # Just another way to write the same users table
  # c.gateways[:default].create_table(:users) do
  #   column :id,   :integer, primary_key: true
  #   column :name, :string, null: false
  #   column :age,  :integer
  #   column :is_admin, :bool
  # end

  c.gateways[:default].create_table :users do
    primary_key :id
    column :name, String, null: false
    column :age, Integer
    column :is_admin, TrueClass
  end

  c.relation(:users) do
    schema(infer: true)
  end
end

users = rom.relations[:users]
puts users.to_a.inspect # => []

create_user = users.command(:create)
create_user.call(name: 'Rob', age: 30, is_admin: true)
puts users.to_a.inspect # never reached

# Uncomment if you want to see the users schema
# puts users.dataset.db.schema(:users)

如果您想使用独立关系类而不是容器配置dsl，那么我建议阅读自动注册系统。

数据库创建问题

有很多事情可能会发生，这些事情可能会阻止创建sqlite数据库。

• 这可能是权限问题
• 目录结构可能不存在。
• Sqlite可能不会被编译来处理URI(仅当您在路径中使用file://时才重要) https://www.sqlite.org/uri.html

我在这里的建议是，当使用sqlite和ROM时，使用上面脚本中的opts散列示例，并尝试使用来自当前工作目录的相对路径。这似乎总是有效的。