Snake case conversion script

util/Readme.md

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+# Utilities directory
+
+A place to hold various utilities to help with dealing with lter_metabase
+
+## snake_case
+
+A ruby script to convert the tables in the `lter_metabase` schema from CamelCase
+to glorious, easy on the fingers snake_case.

util/snake_case/Gemfile

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+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+gem 'main'
+gem 'pg'
+gem 'sequel'

util/snake_case/Readme.md

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+# snake case
+
+A ruby script to convert the tables in the `lter_metabase` schema from CamelCase
+to glorious, easy on the fingers snake_case.
+
+## Usage
+
+Install required gems
+
+```
+$ bundle
+```
+
+to run as a test in a transaction (nothing actually is changed in the db)
+```
+$ ruby to_snake_case lter_metabase
+```
+
+to apply the  changes
+```
+$ ruby to_snake_case.rb lter_metabase --production
+````

util/snake_case/to_snake_case.rb

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+# frozen_string_literal: true
+
+require 'logger'
+require 'main'
+require 'sequel'
+require 'pg'
+
+# monkey patch from ActiveSupport
+class String
+  def underscore
+    self.gsub(/::/, '/').
+      gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
+      gsub(/([a-z\d])([A-Z])/,'\1_\2').
+      tr('-', '_').
+      downcase
+  end
+end
+
+# convert tables and columns of the lter_metabase schema to snake_case if it's
+# not already
+class Snakeify
+  def rename_columns(db, table_schema_and_name, table)
+    db.alter_table(table_schema_and_name) do
+      table.columns.each do |column_name|
+        next if column_name.to_s == column_name.to_s.underscore
+
+        rename_column(column_name, column_name.to_s.underscore)
+      end
+    end
+  end
+
+  def rename_table(db, table_schema_and_name, table_name)
+    db.rename_table(table_schema_and_name, Sequel.qualify(:lter_metabase, table_name.underscore))
+  end
+
+  def to_snake_case(db_name, production)
+    pr = Sequel.postgres(database: db_name, loggers: [Logger.new($stdout)])
+    pr.transaction do
+      query = "select table_name from information_schema.tables where table_schema = 'lter_metabase'"
+      tables = pr[query]
+
+      tables.each do |table_hash|
+        table_name = table_hash[:table_name]
+        table_schema_and_name = Sequel.qualify(:lter_metabase, table_name)
+        table = pr[table_schema_and_name]
+
+        rename_columns(pr, table_schema_and_name, table)
+        next if table_name == table_name.underscore
+
+        rename_table(pr, table_schema_and_name, table_name)
+      end
+      raise unless production
+    end
+  end
+end
+
+Main do
+  argument 'db_name'
+  option 'production'
+
+  def run
+    snake = Snakeify.new
+    snake.to_snake_case(params['db_name'].value,
+                        params['production'].value)
+  end
+end