Question

我是Ruby on Rails的新手，我需要帮助找出如何修改现有的数据库查询。我使用旧版本，我无法更新：Ruby 2.2.3p173和Rails 4.0.2。

我想过滤现有的查询结果，以删除没有任何视频的记录。我认为模型层次结构是：艺术家，专辑组，专辑，曲目，视频。

澄清：我希望艺术家拥有至少1个视频，来自模特协会艺术家 - ＆gt;专辑组 - ＆gt;专辑 - ＆gt;曲目 - ＆gt;视频（不是艺术家 - ＆gt;视频）。

现有查询包含在模型Artist：

中

require_dependency "tagging"
require_dependency "similar"
class Artist < ActiveRecord::Base
  has_many :images, dependent: :destroy
  has_many :taggings, dependent: :destroy
  has_many :artforms, through: :taggings
  has_many :similars, foreign_key: "similar_id", dependent: :destroy
  has_many :similar_artists, through: :similars, source: :similar_to
  has_many :reverse_similars, foreign_key: "similar_to_id", class_name: "Similar", dependent: :destroy
  has_many :similar_to_artists, through: :reverse_similars, source: :similar
  has_many :memberships, foreign_key: "member_id", dependent: :destroy
  has_many :groups, through: :memberships, source: :membership
  has_many :group_members, foreign_key: "membership_id", class_name: "Membership", dependent: :destroy
  has_many :members, through: :group_members, source: :member
  has_many :users, through: :followed_artists
  has_many :videos, dependent: :destroy
  has_many :audios, dependent: :destroy
  has_many :metrics, through: :audios
  has_many :releases, foreign_key: 'artist_id', class_name: "AlbumGroup"
  has_many :albums
  has_many :collaborations
  has_many :album_groups, through: :collaborations
  mount_uploader :mugshot, MugshotUploader
  include PgSearch
  pg_search_scope :for_name,
      against: :name,
      using: { tsearch: {threshold: '1', dictionary: 'simple', tsvector_column: 'tsv_name', prefix: true, normalization: 2}},
      ranked_by: "(artists.popularity / 50 * :tsearch) + :tsearch"
end

我想添加以下内容来过滤掉没有任何视频的记录:(对查询）：

if: artist.releases.albums.tracks.videos.count > 1

或艺术家模型可能？：

scope :valid, -> {where("video_count > 1")}

不同型号的其他代码如下：

class AlbumGroup < ActiveRecord::Base
  belongs_to :artist
  has_many :collaborations
  has_many :artists, through: :collaborations
  has_many :albums
  has_many :taggings, dependent: :destroy
  has_many :artforms, through: :taggings
  mount_uploader :artwork, MugshotUploader
  def as_json options={}
    {
      id: id,
      title: title
    }
  end
end

class Album < ActiveRecord::Base
  belongs_to :album_group
  belongs_to :artist
  has_many :tracks
end

class Track < ActiveRecord::Base
  has_many :playlist_tracks, dependent: :destroy
  has_many :playlists, through: :playlist_tracks
  belongs_to :audio
  belongs_to :video
  has_many :videos
  has_many :audios
  has_many :taggings, dependent: :destroy
  has_many :artforms, through: :taggings
  belongs_to :album
  belongs_to :artist
  default_scope order: "position ASC"
  after_save :cache_columns

  def cache_columns
    if image_url.nil?
      img = album.album_group.artwork_url(:tiny)
      unless img.nil?
        update_column(:image_url,img)
      end
    end
    if artist_name.nil?
      if artist_id
        name = Artist.find(artist_id).name
        update_column(:artist_name,name)
      end
    end
    if album_name.nil?
      if album_id
        title = Album.find(album_id).title
        update_column(:album_name,title)
      end
    end
  end
end

class Video < ActiveRecord::Base
  belongs_to :artist
  belongs_to :event
  belongs_to :track
  has_many :tracks
  has_many :playlists, through: :tracks, order: "tracks.position ASC"
  scope :valid, -> {where("flag_count < 2").order("score DESC") }
  scope :flagged, -> {where("flag_count > ?", 1) }
#   validates :url, uniqueness: {scope: :artist_id}
end

Answer 1

ActiveRecord的has_many和belongs_to方法使您能够直接在关联上定义范围。这样，您可以自定义访问关联时生成的SQL。

假设你想在Artist模型上定义一个范围，该范围返回所有没有视频的艺术家。在Rails 5中，要查找所有没有视频的艺术家，您可以使用left_outer_joins

class Artist < ActiveRecord::Base
  has_many :videos
  scope :with_zero_videos, -> { left_outer_joins(:videos).where(videos: {id: nil}) }
end

另一个好的解决方案是像这样使用includes：

Artist.includes(:videos).where(videos: { videos_id: nil })

您可以选择自己最喜欢的那个！

希望它有所帮助。

Answer 2

感谢Gabriel，我在artists_controller.rb中添加了一个原始的SQL查询，如下所示：

  def index
    #artists = Artist.for_name(params[:name])
    artists = Artist.find_by_sql ["SELECT artists.*, ((artists.popularity / 50 * (ts_rank((artists.tsv_name), (to_tsquery('simple', ''' ' || ? || ' ''' || ':*')), 2))) + (ts_rank((artists.tsv_name), (to_tsquery('simple', ''' ' || ? || ' ''' || ':*')), 2))) AS pg_search_rank FROM artists " +
      "JOIN album_groups on (artists.id = album_groups.artist_id) " +
      "JOIN tracks on (tracks.album_group_id = album_groups.id) " +
      "JOIN videos on (videos.track_id = tracks.id) " +
      "WHERE (((artists.tsv_name) @@ (to_tsquery('simple', ''' ' || ? || ' ''' || ':*')))) " +
      "GROUP BY artists.id " +
      "ORDER BY pg_search_rank DESC, artists.id ASC", params[:name], params[:name], params[:name]]
    render json: artists, each_serializer: SimpleArtistSerializer
  end

ruby on rails过滤pg_search_scope v2.2

2 个答案: