Ruby on rails 使用Rails和Squeel对复杂条件下的结果进行排序

我可能在这里做了一些愚蠢的事情——我也愿意接受其他方式——但我正试图根据计算字段对结果集进行排序：

我的问题是出生日期可能是零。这会导致

cast（（…）.as int）

调用返回三个不同的值-

1

如果表达式的计算结果为

true

<代码>0如果表达式的计算结果为

false

；如果基础列值为

nil

，则为

nil

表达式中的

nil

值导致整个排名评估为

nil

——这意味着，即使我有一个与

姓氏和
给定姓名完全匹配的记录，如果
出生日期列为
nil
，记录的
排名
为
nil

我曾尝试在
cast
中使用一个复杂表达式来检查
是否为nil或匹配的
值，但使用
时出现了一个squel异常，ruby在使用
|
和
或
时对其进行求值

我还尝试按别名列的顺序使用谓词：

order{[`ranking` != nil, `ranking`.desc]}

但这会引发一个
ActiveRecord
异常，抱怨列
ranking
不存在

我已经筋疲力尽了。。。有什么想法吗？
在跳了一段舞之后，我能够使用一系列与其他范围的外部连接来计算
排名，如下所示：

def self.weighted_by_any (client)
  scope = 
    select{[`clients.*`,
            [
             ((cast((`not rank_A.id is null`).as int) * 100) if client[:social_insurance_number].present?),
             ((cast((`not rank_B.id is null`).as int) * 10) if client[:surname].present?),
             ((cast((`not rank_C.id is null`).as int) * 1) if client[:given_names].present?), 
             ((cast((`not rank_D.id is null`).as int) * 1) if client[:date_of_birth].present?)
            ].compact.reduce(:+).as(`ranking`)
          ]}.by_any(client)

  scope = scope.joins{"left join (" + Client.weigh_social_insurance_number(client).to_sql + ") AS rank_A ON rank_A.id = clients.id"} if client[:social_insurance_number].present?
  scope = scope.joins{"left join (" + Client.weigh_surname(client).to_sql + ") AS rank_B on rank_B.id = clients.id"} if client[:surname].present?
  scope = scope.joins{"left join (" + Client.weigh_given_names(client).to_sql + ") AS rank_C on rank_C.id = clients.id"} if client[:given_names].present?
  scope = scope.joins{"left join (" + Client.weigh_date_of_birth(client).to_sql + ") AS rank_D on rank_D.id = clients.id"} if client[:date_of_birth].present?
  scope.order{`ranking`.desc}
end

其中
客户端。称重。以下是我的想法：

首先，我用筛选器替换了
称重（客户端）
范围。我以前发现，您可以在范围的
select{}
部分使用筛选器，我们将在一分钟内使用它

sifter :weigh_social_insurance_number do |token|
  # check if the token is present - we don't want to match on nil, but we want the column in the results
  # cast the comparison of the token to the column to an integer -> nil = nil, true = 1, false = 0
  # use coalesce to replace the nil value with `0` (for no match)
  (token.present? ? coalesce(cast((social_insurance_number == token).as int), `0`) : `0`).as(weight_social_insurance_number)
end

sifter :weigh_surname do |token|
  (token.present? ? coalesce(cast((surname == token).as int), `0`) :`0`).as(weight_surname)
end

sifter :weigh_given_names do |token|
  (token.present? ? coalesce(cast((given_names == token).as int), `0`) : `0`).as(weight_given_names)
end

sifter :weigh_date_of_birth do |token|
  (token.present? ? coalesce(cast((date_of_birth == token).as int), `0`) : `0`).as(weight_date_of_birth)
end

因此，让我们使用筛选器创建一个范围来衡量我们的所有标准：

def self.weigh_criteria (client)
  select{[`*`, 
          sift(weigh_social_insurance_number, client[:social_insurance_number]),
          sift(weigh_surname, client[:surname]),
          sift(weigh_given_names, client[:given_names]),
          sift(weigh_date_of_birth, client[:date_of_birth])
        ]}
end

现在我们可以确定提供的标准是否与列值匹配，我们使用另一个筛选器计算排名：

sifter :ranking do
  (weight_social_insurance_number * 100 + weight_surname * 10 + weight_date_of_birth * 5 + weight_given_names).as(ranking)
end

并将其加在一起，使我们的范围包括所有模型属性和计算属性：

def self.weighted_by_any (client)
  # check if the date is valid 
  begin 
    client[:date_of_birth] = Date.parse(client[:date_of_birth])
  rescue => e
    client.delete(:date_of_birth)
  end

  select{[`*`, sift(ranking)]}.from("(#{weigh_criteria(client).by_any(client).to_sql}) clients").order{`ranking`.desc}
end

因此，我现在可以搜索一个客户，并根据其与提供的标准的匹配程度对结果进行排序：

irb(main): Client.weighted_by_any(client)
  Client Load (8.9ms)  SELECT *, 
                              "clients"."weight_social_insurance_number" * 100 + 
                              "clients"."weight_surname" * 10 + 
                              "clients"."weight_date_of_birth" * 5 + 
                              "clients"."weight_given_names" AS ranking 
                       FROM (
                             SELECT *, 
                                    coalesce(cast("clients"."social_insurance_number" = '<sin>' AS int), 0) AS weight_social_insurance_number, 
                                    coalesce(cast("clients"."surname" = '<surname>' AS int), 0) AS weight_surname, 
                                    coalesce(cast("clients"."given_names" = '<given_names>' AS int), 0) AS weight_given_names,         0 AS weight_date_of_birth 
                             FROM "clients" 
                             WHERE ((("clients"."social_insurance_number" = '<sin>' 
                                   OR "clients"."surname" ILIKE '<surname>%') 
                                   OR "clients"."given_names" ILIKE '<given_names>%'))
                            ) clients 
                       ORDER BY ranking DESC

irb（主）：客户端。按任意（客户端）加权
客户端负载（8.9ms）选择*，
“客户”.“权重、社会保险号”*100+
“客户”.“体重姓氏”*10+
“客户”，“体重、出生日期”*5+
“客户”，“权重”作为排名
从(
选择*，
合并（强制转换（“客户”，“社会保险号”=''为整数），0）为权重（社会保险号），
合并（强制转换（“客户”。“姓氏”=”为int），0）为权重\姓氏，
合并（强制转换（“客户端”。“给定名称”=''为int），0）为权重\u给定名称，0为权重\u出生日期\u
来自“客户”
式中（（“客户”，“社会保险号”=”
或“客户”。“姓氏”类似“%”）
或“客户端”。“给定名称”类似“%”）
)客户
按等级顺序描述

更干净，更优雅，工作更好

def self.weighted_by_any (client)
  # check if the date is valid 
  begin 
    client[:date_of_birth] = Date.parse(client[:date_of_birth])
  rescue => e
    client.delete(:date_of_birth)
  end

  select{[`*`, sift(ranking)]}.from("(#{weigh_criteria(client).by_any(client).to_sql}) clients").order{`ranking`.desc}
end

irb(main): Client.weighted_by_any(client)
  Client Load (8.9ms)  SELECT *, 
                              "clients"."weight_social_insurance_number" * 100 + 
                              "clients"."weight_surname" * 10 + 
                              "clients"."weight_date_of_birth" * 5 + 
                              "clients"."weight_given_names" AS ranking 
                       FROM (
                             SELECT *, 
                                    coalesce(cast("clients"."social_insurance_number" = '<sin>' AS int), 0) AS weight_social_insurance_number, 
                                    coalesce(cast("clients"."surname" = '<surname>' AS int), 0) AS weight_surname, 
                                    coalesce(cast("clients"."given_names" = '<given_names>' AS int), 0) AS weight_given_names,         0 AS weight_date_of_birth 
                             FROM "clients" 
                             WHERE ((("clients"."social_insurance_number" = '<sin>' 
                                   OR "clients"."surname" ILIKE '<surname>%') 
                                   OR "clients"."given_names" ILIKE '<given_names>%'))
                            ) clients 
                       ORDER BY ranking DESC