使用 Mongoid 时对 Criteria 的每一次引用都会触发一次数据库查询？

rbprocareer — Mon, 20 Jul 2015 11:38:55 +0800

drawings = Drawing.published.includes(:user).limit(10)
drawing_ids = drawings.map(&:id)
drawing_user_ids = drawings.map { |drawing| drawing.user.id }

logs:

Started GET "/api/hot" for 127.0.0.1 at 2015-07-20 10:55:18 +0800
  MOPED: 127.0.0.1:27017 COMMAND      database=admin command={:ismaster=>1} runtime: 0.7450ms
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=drawings selector={"published"=>true} flags=[] limit=10 skip=0 batch_size=nil fields=nil runtime: 1.4050ms
  MOPED: 127.0.0.1:27017 KILL_CURSORS cursor_ids=[40708006394] runtime: 0.1960ms
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"_id"=>{"$in"=>[3, 7, 10, 9, 4, 16, 11]}} flags=[] limit=0 skip=0 batch_size=nil fields=nil runtime: 1.5960ms
QUERY CACHE  database=ki_backend_development collection=drawings selector={"published"=>true}
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"$query"=>{"_id"=>3}, "$orderby"=>{:_id=>1}} flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 0.5010ms
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"$query"=>{"_id"=>7}, "$orderby"=>{:_id=>1}} flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 1.1690ms
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"$query"=>{"_id"=>10}, "$orderby"=>{:_id=>1}} flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 0.5130ms
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>7}, "$orderby"=>{:_id=>1}}
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"$query"=>{"_id"=>9}, "$orderby"=>{:_id=>1}} flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 0.8260ms
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"$query"=>{"_id"=>4}, "$orderby"=>{:_id=>1}} flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 1.6400ms
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"$query"=>{"_id"=>16}, "$orderby"=>{:_id=>1}} flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 0.3710ms
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>4}, "$orderby"=>{:_id=>1}}
  MOPED: 127.0.0.1:27017 QUERY        database=ki_backend_development collection=users selector={"$query"=>{"_id"=>11}, "$orderby"=>{:_id=>1}} flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 0.3980ms
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>16}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=drawings selector={"published"=>true}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>3}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>7}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>10}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>7}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>9}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>4}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>16}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>4}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>11}, "$orderby"=>{:_id=>1}}
QUERY CACHE  database=ki_backend_development collection=users selector={"$query"=>{"_id"=>16}, "$orderby"=>{:_id=>1}}

Mongoid 版本为 4.0.2

carrierwave 本地目录

rbprocareer — Sun, 05 Oct 2014 00:34:35 +0800

carrierwave 上传图片到本地存储的比较合适的目录是什么？默认是和项目在一起，在 public 下，这样以后项目要迁移的话就比较麻烦。放在项目目录结构外的某个文件系统目录，不确定项目能够访问的到。做个链接视乎也不太妙？

Grape 返回 JSON 格式太不灵活

rbprocareer — Mon, 25 Aug 2014 14:57:27 +0800

我期望返回以下格式的数据：

{
    code: 1000,
    msg: "OK",
    data: {
        // normal data goes here if exists
    }
}

present 具体 Entity 时挺好用的，但涉及到内嵌结构的时候就不灵了

// ok
present :items, Book.all, with: Entities::Book

// does not work
resources :books do
    get do
        present :code, 1000
        present :msg, "OK"
        present :data do
            present :items, Book.all, with: Entities::Book
        end
    end
end

本来手动组织这样的结构是微不足道的，引入框架后反而这个过程变得异常复杂和不灵活！～请问有什么替代方法吗？