From e63524f45792af83cf802270c3beebc76bada645 Mon Sep 17 00:00:00 2001
From: Matt Jankowski <matt@jankowski.online>
Date: Sat, 25 Mar 2023 19:37:57 -0400
Subject: [PATCH] Update retention model sql query (#24249)

---
 app/lib/admin/metrics/retention.rb | 56 ++++++++++++++++++------------
 1 file changed, 33 insertions(+), 23 deletions(-)

diff --git a/app/lib/admin/metrics/retention.rb b/app/lib/admin/metrics/retention.rb
index f6135ac1e..9bd47c58e 100644
--- a/app/lib/admin/metrics/retention.rb
+++ b/app/lib/admin/metrics/retention.rb
@@ -42,25 +42,54 @@ class Admin::Metrics::Retention
   end
 
   def perform_query
-    sql = <<-SQL.squish
+    report_rows.each_with_object([]) do |row, arr|
+      current_cohort = arr.last
+
+      if current_cohort.nil? || current_cohort.period != row['cohort_period']
+        current_cohort = Cohort.new(period: row['cohort_period'], frequency: @frequency, data: [])
+        arr << current_cohort
+      end
+
+      value, rate = row['retention_value_and_rate'].delete('{}').split(',')
+
+      current_cohort.data << CohortData.new(
+        date: row['retention_period'],
+        rate: rate.to_f,
+        value: value.to_s
+      )
+    end
+  end
+
+  def report_rows
+    ActiveRecord::Base.connection.select_all(sanitized_sql_string)
+  end
+
+  def sanitized_sql_string
+    ActiveRecord::Base.sanitize_sql_array(
+      [sql_query_string, { start_at: @start_at, end_at: @end_at, frequency: @frequency }]
+    )
+  end
+
+  def sql_query_string
+    <<~SQL.squish
       SELECT axis.*, (
         WITH new_users AS (
           SELECT users.id
           FROM users
-          WHERE date_trunc($3, users.created_at)::date = axis.cohort_period
+          WHERE date_trunc(:frequency, users.created_at)::date = axis.cohort_period
         ),
         retained_users AS (
           SELECT users.id
           FROM users
           INNER JOIN new_users on new_users.id = users.id
-          WHERE date_trunc($3, users.current_sign_in_at) >= axis.retention_period
+          WHERE date_trunc(:frequency, users.current_sign_in_at) >= axis.retention_period
         )
         SELECT ARRAY[count(*), (count(*))::float / (SELECT GREATEST(count(*), 1) FROM new_users)] AS retention_value_and_rate
         FROM retained_users
       )
       FROM (
         WITH cohort_periods AS (
-          SELECT generate_series(date_trunc($3, $1::timestamp)::date, date_trunc($3, $2::timestamp)::date, ('1 ' || $3)::interval) AS cohort_period
+          SELECT generate_series(date_trunc(:frequency, :start_at::timestamp)::date, date_trunc(:frequency, :end_at::timestamp)::date, ('1 ' || :frequency)::interval) AS cohort_period
         ),
         retention_periods AS (
           SELECT cohort_period AS retention_period FROM cohort_periods
@@ -70,24 +99,5 @@ class Admin::Metrics::Retention
         WHERE retention_period >= cohort_period
       ) as axis
     SQL
-
-    rows = ActiveRecord::Base.connection.select_all(sql, nil, [[nil, @start_at], [nil, @end_at], [nil, @frequency]])
-
-    rows.each_with_object([]) do |row, arr|
-      current_cohort = arr.last
-
-      if current_cohort.nil? || current_cohort.period != row['cohort_period']
-        current_cohort = Cohort.new(period: row['cohort_period'], frequency: @frequency, data: [])
-        arr << current_cohort
-      end
-
-      value, rate = row['retention_value_and_rate'].delete('{}').split(',')
-
-      current_cohort.data << CohortData.new(
-        date: row['retention_period'],
-        rate: rate.to_f,
-        value: value.to_s
-      )
-    end
   end
 end