Question

如何在rails

中的Active Record查询中重写此SQL查询

sqlQuery = "SELECT real_estate_agent_assignment_statuses.assignment_status, 
COUNT(developer_referrals.id) AS rea_count FROM 
real_estate_agent_assignment_statuses LEFT OUTER JOIN developer_referrals ON 
developer_referrals.real_estate_agent_assignment_status_id = 
real_estate_agent_assignment_statuses.id AND developer_referrals.project_id =
 1 AND developer_referrals.developer_staff_id IN (266) WHERE 
real_estate_agent_assignment_statuses.assignment_status IN ('Pending 
Eligibility Check', 'Completed Eligibility Check') AND 
real_estate_agent_assignment_statuses.deleted_at IS NULL GROUP BY 
real_estate_agent_assignment_statuses.assignment_status, 
real_estate_agent_assignment_statuses.rank ORDER BY 
real_estate_agent_assignment_statuses.rank ASC"

Answer 1

我的SQL很生疏，但我认为这会让你开始。

'columnDefs': [
    { 'orderData':[1], 'targets': [0] },
    {
        'targets': [1],
        'visible': false,
        'searchable': false
    },
],

http://apidock.com/rails/ActiveRecord/QueryMethods

Answer 2

设置正确的scopes并建立关系，您几乎可以做任何事情。

第一步是定义关系和范围。我只猜测你的人际关系是什么，但即使完全不同，下面的代码也应该大致说明它是如何运作的：

class DeveloperReferral < ActiveRecord::Base
  belongs_to :project
  belongs_to :staff_member

  scope :with_project, ->(project) {
    # merging allows you to define conditions on the join
    joins(:project).merge( Project.where(id: project) )
  }

  scope :with_staff_member, ->(staff_member) {
    # merging allows you to define conditions on the join
    joins(:staff_member).merge( StaffMember.where(id: staff_member) )
  }
end

class RealEstateAgentAssignmentStatus < ActiveRecord::Base
  has_many :developer_referrals

  scope :with_status, ->(status) { where(status: status) }
  scope :not_deleted, -> { where(deleted_at: nil) }

  scope :with_project, ->(project) {
    # merging allows you to define conditions on the join
    joins(:developer_referrals).merge(
        DeveloperReferral.with_project(project)
      )
  }

  scope :with_staff_member, ->(staff_member) {
    # merging allows you to define conditions on the join
    joins(:developer_referrals).merge(
        DeveloperReferral.with_staff_member(staff_member)
      )
  }
end

然后，您可以使用范围构建查询。

project = Project.find(1)
staff_members = project.staff_members

statuses =
  RealEstateAgentAssignmentStatus
    .with_project(project)
    .with_staff_member(staff_members)
    .with_status([
        'Pending Eligibility Check',
        'Completed Eligibility Check',
      ])
    .not_deleted
    .order(
        # we use `arel_table` so that SQL uses the namespaced column name
        RealEstateAgentAssignmentStatus.arel_table(:rank),
      )

然后你可以做你的小组/计数：

status_counts =
  statuses
    .group(
        # we use `arel_table` so that SQL uses the namespaced column name
        RealEstateAgentAssignmentStatus.arel_table(:assignment_status),
        RealEstateAgentAssignmentStatus.arel_table(:rank),
      )
    .count(:id)

在Rails 4中将SQL Query转换并优化为Active Record查询

2 个答案: