如何通过ransack gem搜索数组？

Question

我正在ransack gem用于在rails应用程序中搜索.我需要搜索的数组email_ids中的User表.

在洗劫时提到这个问题,我按照步骤将其添加到初始化文件夹中ransack.rb

Ransack.configure do |config|
   {
    contained_within_array: :contained_within,
    contained_within_or_equals_array: :contained_within_or_equals,
    contains_array: :contains,
    contains_or_equals_array: :contains_or_equals,
    overlap_array: :overlap
   }.each do |rp, ap|
   config.add_predicate rp, arel_predicate: ap, wants_array: true
  end
end

在rails控制台中,如果我喜欢这样:

a = User.search(email_contains_array: ['priti@gmail.com'])

它产生这样的sql:

"SELECT \"users\".* FROM \"users\" WHERE \"users\".\"deleted_at\" IS NULL AND (\"users\".\"email\" >> '---\n- priti@gmail.com\n')"

并给出如下错误:

  User Load (1.8ms)  SELECT "users".* FROM "users" WHERE "users"."deleted_at" IS NULL AND ("users"."email" >> '---
- priti@gmail.com
')
 ActiveRecord::StatementInvalid: PG::UndefinedFunction: ERROR: operator does not exist: character varying >> unknown
 LINE 1: ...RE "users"."deleted_at" IS NULL AND ("users"."email" >> '---
                                                            ^
 HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.
 : SELECT "users".* FROM "users" WHERE "users"."deleted_at" IS NULL AND ("users"."email" >> '---
 - priti@gmail.com
')

预期是这个查询:

SELECT "users".* FROM "users"  WHERE ("users"."roles" @> '{"3","4"}')

我做错了什么？

Answer 1

我遇到了和你一样的问题.我使用Rails 5,我需要搜索的数组roles中的User表

您似乎已经添加postgres_ext gem了gemfile,但如果您在Rails 5应用程序中使用它,则会出现一些问题.

因此,您可以contain自行选择在Arel Node中添加查询,而不是使用postgres_ext gem

如果您使用的是其他版本的Rails,我认为它的效果也很好.

我有一个User模型和一个数组属性roles.我想要做的是ransack用来搜索roles.这和你的情况一样.

ransack无法搜索数组.但是PostgresSQL可以像这样搜索数组:

User.where("roles @> ?", '{admin}').to_sql)

它产生这样的SQL查询:

SELECT "users".* FROM "users" WHERE "users"."deleted_at" IS NULL AND (roles @> '{admin}')

所以我想要做的是添加一个类似的包含查询 Arel Nodes

你能做到这样:

# app/config/initializers/arel.rb

require 'arel/nodes/binary'
require 'arel/predications'
require 'arel/visitors/postgresql'

module Arel
  class Nodes::ContainsArray < Arel::Nodes::Binary
    def operator
      :"@>"
    end
  end

  class Visitors::PostgreSQL
    private

    def visit_Arel_Nodes_ContainsArray(o, collector)
      infix_value o, collector, ' @> '
    end
  end

  module Predications
    def contains(other)
      Nodes::ContainsArray.new self, Nodes.build_quoted(other, self)
    end
  end
end

因为你可以自定义洗劫谓语,所以加contains搜查谓语像这样:

# app/config/initializers/ransack.rb

Ransack.configure do |config|
  config.add_predicate 'contains',
    arel_predicate: 'contains',
    formatter: proc { |v| "{#{v}}" },
    validator: proc { |v| v.present? },
    type: :string
end

完成!

现在,您可以搜索数组:

User.ransack(roles_contains: 'admin')

SQL查询将如下所示:

SELECT \"users\".* FROM \"users\" WHERE \"users\".\"deleted_at\" IS NULL AND (\"users\".\"roles\" @> '{[\"admin\"]}')

是啊!