Rails 活动记录查询以检索包含 IDS 数组中所有 IDS 的所有记录
Rails active record query to retrive all records that contains ALL IDS in the array of IDS
一个视频可以有多个类别。
video.rb
has_many :video_categories
has_many :categories, through: :video_categories
category.rb
has_many :video_categories
has_many :videos, through: :video_categories
我有这个简单的表单,允许用户 select 他想要组合的类别以查找特定视频。例如,有一个“python”类别和“高级”类别。如果他 select编辑了这两个类别,它应该会显示包含这两个类别的视频。
视频 A - 类别 [1,4,7](这是类别 ID)
视频 B - 类别 [1,2,7,9]
视频 C - 类别 [7,9]
如果用户 select 类别 [1,7],输出应该是视频 A 和 B。当前范围我有它返回的所有视频具有类别 1,所有视频具有类别7 和包含两者的视频。
我只想要包含这两个视频的视频。我该怎么做?
当前范围:
video.rb
scope :for_categories, -> (category_ids) {
joins(:video_categories).where(
video_categories: { category_id: category_ids }
)
}
pages_controller.rb
def search
@results = Video.for_categories(params[:category_ids])
end
我的表格
<%= form_with url: "/search", method: :get do |form| %>
<%= form.collection_check_boxes(:category_ids, Category.all,
:id, :title, { prompt: 'None'}, { multiple: true} ) do |cat| %>
<label class="text-capitalize checkbox-inline mr-2">
<%= cat.check_box %>
<%= cat.label %>
</label>
<% end %>
<%= form.submit "Search" %>
<% end %>
您想应用一个 GROUP 并使用 HAVING 对组设置条件以确保加入的类别数与 ID 数相匹配:
class Video
def self.for_categories(*category_ids)
ids = category_ids.flatten # handles a single array as input
group(:id)
.joins(:categories)
.where(categories: { id: ids })
.having(
Category.arel_table[:id]
.count
.gteq(ids.length)
)
end
end
根据 SQL 这会给你这样的东西:
SELECT videos.*
FROM videos
INNER JOIN video_categories ON video_categories.video_id = videos.id
INNER JOIN categories ON video_categories.category_id = categories.id
WHERE categories.id IN (1, 2, 3)
GROUP BY videos.id
HAVING COUNT(categories.id) >= 3
我能够通过以下代码找到解决方案
video.rb
scope :by_categories, -> (category_ids) {
joins(:categories).where(categories: [category_ids] )
}
scope :by_all_categories, -> (category_ids) {
by_categories(category_ids).
group("videos.id").
having('count(videos.id) >= ?', category_ids.size)
}
pages_controller.rb
def search
@results = Video.by_all_categories(params[:category_ids].reject(&:empty?))
end
categories_to_search = [1, 7]
conditions = categories_to_search.map do |c|
{ viedo_categories: { category_id: c } }
do
Video.where conditions
# this is the same as: Video.where viedo_categories: { category_id: 1 }, viedo_categories: { category_id: 7 }
一个视频可以有多个类别。
video.rb
has_many :video_categories
has_many :categories, through: :video_categories
category.rb
has_many :video_categories
has_many :videos, through: :video_categories
我有这个简单的表单,允许用户 select 他想要组合的类别以查找特定视频。例如,有一个“python”类别和“高级”类别。如果他 select编辑了这两个类别,它应该会显示包含这两个类别的视频。
视频 A - 类别 [1,4,7](这是类别 ID)
视频 B - 类别 [1,2,7,9]
视频 C - 类别 [7,9]
如果用户 select 类别 [1,7],输出应该是视频 A 和 B。当前范围我有它返回的所有视频具有类别 1,所有视频具有类别7 和包含两者的视频。
我只想要包含这两个视频的视频。我该怎么做?
当前范围:
video.rb
scope :for_categories, -> (category_ids) {
joins(:video_categories).where(
video_categories: { category_id: category_ids }
)
}
pages_controller.rb
def search
@results = Video.for_categories(params[:category_ids])
end
我的表格
<%= form_with url: "/search", method: :get do |form| %>
<%= form.collection_check_boxes(:category_ids, Category.all,
:id, :title, { prompt: 'None'}, { multiple: true} ) do |cat| %>
<label class="text-capitalize checkbox-inline mr-2">
<%= cat.check_box %>
<%= cat.label %>
</label>
<% end %>
<%= form.submit "Search" %>
<% end %>
您想应用一个 GROUP 并使用 HAVING 对组设置条件以确保加入的类别数与 ID 数相匹配:
class Video
def self.for_categories(*category_ids)
ids = category_ids.flatten # handles a single array as input
group(:id)
.joins(:categories)
.where(categories: { id: ids })
.having(
Category.arel_table[:id]
.count
.gteq(ids.length)
)
end
end
根据 SQL 这会给你这样的东西:
SELECT videos.*
FROM videos
INNER JOIN video_categories ON video_categories.video_id = videos.id
INNER JOIN categories ON video_categories.category_id = categories.id
WHERE categories.id IN (1, 2, 3)
GROUP BY videos.id
HAVING COUNT(categories.id) >= 3
我能够通过以下代码找到解决方案
video.rb
scope :by_categories, -> (category_ids) {
joins(:categories).where(categories: [category_ids] )
}
scope :by_all_categories, -> (category_ids) {
by_categories(category_ids).
group("videos.id").
having('count(videos.id) >= ?', category_ids.size)
}
pages_controller.rb
def search
@results = Video.by_all_categories(params[:category_ids].reject(&:empty?))
end
categories_to_search = [1, 7]
conditions = categories_to_search.map do |c|
{ viedo_categories: { category_id: c } }
do
Video.where conditions
# this is the same as: Video.where viedo_categories: { category_id: 1 }, viedo_categories: { category_id: 7 }