Rails 从同一个表中查询多个参数

Question

如何搜索多个参数？我的视图中有复选框，所以如果选择了多个复选框，我希望选择所有 params。我目前只能使用下面的代码使用param 进行搜索。

car 模型和 colour_collection 模型之间存在 has_many 到 has_many 关联。

控制器：

@cars = car.joins(:colour_collections).where("colour_collections.name = ?", params[:colour_collection])

如果选择了两种颜色（例如红色和绿色）在结果查询中创建重复项，则日志会显示这一点：

(0.7ms)  SELECT COUNT(*) FROM "colour_collections"
  ColourCollection Load (0.5ms)  SELECT "colour_collections".* FROM "colour_collections"
  Car Load (2.5ms)  SELECT "cars".* FROM "cars" INNER JOIN "car_colour_collections" ON "car_colour_collections"."car_id" = "cars"."id" INNER JOIN "colour_collections" ON "colour_collections"."id" = "car_colour_collections"."colour_collection_id" WHERE "colour_collections"."name" IN ('Subtle', 'Intermediate') ORDER BY "cars"."created_at" DESC
  CarAttachment Load (0.5ms)  SELECT  "car_attachments".* FROM "car_attachments" WHERE "car_attachments"."car_id" = $1 ORDER BY "car_attachments"."id" ASC LIMIT $2  [["car_id", 21], ["LIMIT", 1]]
  CACHE (0.0ms)  SELECT  "car_attachments".* FROM "car_attachments" WHERE "car_attachments"."car_id" = $1 ORDER BY "car_attachments"."id" ASC LIMIT $2  [["car_id", 21], ["LIMIT", 1]]
  CarAttachment Load (0.5ms)  SELECT  "car_attachments".* FROM "car_attachments" WHERE "car_attachments"."car_id" = $1 ORDER BY "car_attachments"."id" ASC LIMIT $2  [["car_id", 20], ["LIMIT", 1]]
  CACHE (0.0ms)  SELECT  "car_attachments".* FROM "car_attachments" WHERE "car_attachments"."car_id" = $1 ORDER BY "car_attachments"."id" ASC LIMIT $2  [["car_id", 20], ["LIMIT", 1]]

Answer 1

例如，如果您想在单个列中搜索多个值

params[:colour_collection] = ['red','green','blue'] 

那么你会期望你的查询看起来像这样

SELECT * FROM cars c 
INNER JOIN colour_collections s 
WHERE s.name IN ('red','green','blue');

在这种情况下，相应的 ActiveRecord 语句将如下所示

Car.
joins(:colour_collections).
where(colour_collections: { name: params[:colour_collection] })

Answer 2

Rails 5 带有 or 方法，但 Rails 4 没有 or 方法，因此您可以在 Rails 4 中使用纯 SQL 查询。

在 Rails 4 中：

@cars = car.
        joins(:colour_collections).
        where("colour_collections.name = ? or colour_collections.type = ?", params[:colour_collection], params[:type])

在 Rails 5 中：

@cars = car.
        joins(:colour_collections).
        where("colour_collections.name = ?", params[:colour_collection]).or(car.joins(:colour_collections).where("colour_collections.type = ?", params[:type]))

Answer 3

取决于您是要使用OR 还是AND。有多种方法可以实现这一点，但简单的例子是

Article.where(trashed: true).where(trashed: false)
生成的 sql 将是
SELECT * FROM articles WHERE 'trashed' = 1 AND 'trashed' = 0

Foo.where(foo: 'bar').or.where(bar: 'bar') 这是 Rails 5 中的标准，或者只是
Foo.where('foo= ? OR bar= ?', 'bar', 'bar')

Answer 4

@cars = car.joins(:colour_collections).where("colour_collections.name = ?", params[:colour_collection]).where("cars.make = ?", params[:make])

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