小编mra*_*bin的帖子

我正在尝试将每个播放列表的第一首歌加入到一系列播放列表中,并且我很难找到有效的解决方案.

我有以下型号:

class Playlist < ActiveRecord::Base
  belongs_to :user
  has_many :playlist_songs
  has_many :songs, :through => :playlist_songs
end

class PlaylistSong < ActiveRecord::Base
  belongs_to :playlist
  belongs_to :song
end

class Song < ActiveRecord::Base
  has_many :playlist_songs
  has_many :playlists, :through => :playlist_songs
end

我想得到这个:

playlist_name  |  song_name
----------------------------
chill          |  baby
fun            |  bffs

我很难找到通过加入来实现这一目标的有效方法.

更新****

Shane Andrade带领我朝着正确的方向前进,但我仍然无法得到我想要的东西.

这是我能够得到的:

playlists = Playlist.where('id in (1,2,3)')

playlists.joins(:playlist_songs)
         .group('playlists.id')
         .select('MIN(songs.id) as song_id, playlists.name as playlist_name')

这给了我:

playlist_name  |  song_id
---------------------------
chill          |  1

这很接近,但我需要第一首歌(根据id)的名字.

如何确定YouTube视频是实际视频还是静态图像？

由于使用youtube API可能无法实现,是否有使用javascript/jquery扫描窗口给定区域中的像素并确定它们是否已更改的解决方法？

我是新手,我正在构建一个非常简单的应用程序.我可以通过点击链接到标签生成的链接,从我的育种者索引页面(/育种者)导航到我的育种者展示页面(/ breeders /:breeder_id).但是,如果我手动导航到breeders/1或任何其他breeders.show路由,我会收到以下错误:

Error while loading route: ReferenceError: params is not defined
at Catapp.BreedersShowRoute.Ember.Route.extend.model

我无法弄清楚我做了什么导致了这一点.

这就是我认为的相关代码:

    //router.js
    Catapp.Router.map(function() {
        this.resource('breeders', function() {
            this.route('new');
            this.route('show', {path: '/:breeder_id'});
        });
    });

    Catapp.IndexRoute = Ember.Route.extend({
        redirect: function(){
            this.transitionTo('breeders.index');
        }
    });

    Catapp.BreedersIndexRoute = Ember.Route.extend({
        model: function(){
            return this.store.find('breeder');
        }
    });

    Catapp.BreedersShowRoute = Ember.Route.extend({
        model: function(){
            return this.store.find('breeder', params.breeder_id);
        }
    });

.

// breeders_controller.js
Catapp.BreedersController = Ember.ArrayController.extend({
    sortProperties: ['id']
});

我正在尝试使用 rancher REST api 创建容器并将其添加到 rancher 中的现有服务。

我希望以下请求会创建一个容器并将其添加到 atlas-mosquitto 堆栈和 mosquitto 服务（见标签）。

curl -u "${RANCHER_ACCESS_KEY}:${RANCHER_SECRET_KEY}" \
-X POST \
-H 'Accept: application/json' \
-H 'Content-Type: application/json' \
-d '{"count":1, "imageUuid":"docker:dummy/atlas/mosquitto:0.0.8", "name":"atlas-mosquitto_mosquitto_dummy_name", "startOnCreate":true, "labels": {"io.rancher.service.deployment.unit": "acdaf002-e1d0-4625-ba9c-3e1dbc584a14", "io.rancher.project.name": "atlas-mosquitto", "io.rancher.container.pull_image": "always", "io.rancher.scheduler.affinity:container_label_soft_ne": "io.rancher.stack_service.name=atlas-mosquitto/mosquitto", "io.rancher.service.launch.config": "io.rancher.service.primary.launch.config", "io.rancher.project_service.name": "atlas-mosquitto/mosquitto", "io.rancher.stack.name": "atlas-mosquitto", "io.rancher.stack_service.name": "atlas-mosquitto/mosquitto"},  "publishAllPorts":false, "privileged":false, "stdinOpen":false, "tty":false, "readOnly":false' \
'https://rancher-ha.dummy.info/v1/projects/1a29/containers'

下面是身体的漂亮印刷品，以便于阅读：

{
  "count": 1,
  "imageUuid": "docker:dummy\/atlas\/mosquitto:0.0.8",
  "name": "atlas-mosquitto_mosquitto_dummy_name",
  "startOnCreate": true,
  "labels": {
    "io.rancher.service.deployment.unit": "acdaf002-e1d0-4625-ba9c-3e1dbc584a14",
    "io.rancher.project.name": "atlas-mosquitto",
    "io.rancher.container.pull_image": "always",
    "io.rancher.scheduler.affinity:container_label_soft_ne": "io.rancher.stack_service.name=atlas-mosquitto\/mosquitto",
    "io.rancher.service.launch.config": "io.rancher.service.primary.launch.config",
    "io.rancher.project_service.name": "atlas-mosquitto\/mosquitto", …