Module: ArelExtensions

Defined in:
lib/arel_extensions/visitors/oracle.rb,
lib/arel_extensions/math.rb,
lib/arel_extensions/aliases.rb,
lib/arel_extensions/helpers.rb,
lib/arel_extensions/railtie.rb,
lib/arel_extensions/version.rb,
lib/arel_extensions/nodes/abs.rb,
lib/arel_extensions/nodes/md5.rb,
lib/arel_extensions/nodes/std.rb,
lib/arel_extensions/nodes/sum.rb,
lib/arel_extensions/attributes.rb,
lib/arel_extensions/nodes/case.rb,
lib/arel_extensions/nodes/cast.rb,
lib/arel_extensions/nodes/ceil.rb,
lib/arel_extensions/nodes/json.rb,
lib/arel_extensions/nodes/rand.rb,
lib/arel_extensions/nodes/then.rb,
lib/arel_extensions/nodes/trim.rb,
lib/arel_extensions/nodes/wday.rb,
lib/arel_extensions/comparators.rb,
lib/arel_extensions/nodes/blank.rb,
lib/arel_extensions/nodes/floor.rb,
lib/arel_extensions/nodes/log10.rb,
lib/arel_extensions/nodes/power.rb,
lib/arel_extensions/nodes/round.rb,
lib/arel_extensions/nodes/union.rb,
lib/arel_extensions/nodes/format.rb,
lib/arel_extensions/nodes/length.rb,
lib/arel_extensions/nodes/locate.rb,
lib/arel_extensions/nodes/repeat.rb,
lib/arel_extensions/predications.rb,
lib/arel_extensions/date_duration.rb,
lib/arel_extensions/nodes/collate.rb,
lib/arel_extensions/nodes/is_null.rb,
lib/arel_extensions/nodes/matches.rb,
lib/arel_extensions/nodes/replace.rb,
lib/arel_extensions/nodes/soundex.rb,
lib/arel_extensions/set_functions.rb,
lib/arel_extensions/insert_manager.rb,
lib/arel_extensions/math_functions.rb,
lib/arel_extensions/nodes/coalesce.rb,
lib/arel_extensions/nodes/duration.rb,
lib/arel_extensions/nodes/function.rb,
lib/arel_extensions/null_functions.rb,
lib/arel_extensions/visitors/mssql.rb,
lib/arel_extensions/visitors/mysql.rb,
lib/arel_extensions/nodes/date_diff.rb,
lib/arel_extensions/nodes/substring.rb,
lib/arel_extensions/nodes/union_all.rb,
lib/arel_extensions/visitors/ibm_db.rb,
lib/arel_extensions/visitors/sqlite.rb,
lib/arel_extensions/visitors/to_sql.rb,
lib/arel_extensions/string_functions.rb,
lib/arel_extensions/boolean_functions.rb,
lib/arel_extensions/nodes/change_case.rb,
lib/arel_extensions/nodes/find_in_set.rb,
lib/arel_extensions/visitors/oracle12.rb,
lib/arel_extensions/visitors/postgresql.rb,
lib/arel_extensions/common_sql_functions.rb,
lib/arel_extensions/nodes/formatted_date.rb,
lib/arel_extensions/nodes/formatted_number.rb,
lib/arel_extensions/visitors/convert_format.rb,
lib/arel_extensions/nodes/aggregate_function.rb,
lib/arel_extensions/nodes/levenshtein_distance.rb

Overview

require ‘oracle_visitor’

Defined Under Namespace

Modules: Aliases, Attributes, BooleanFunctions, Comparators, DateDuration, InsertManager, Math, MathFunctions, Nodes, NullFunctions, Predications, SetFunctions, StringFunctions, Visitors Classes: CommonSqlFunctions, Railtie

Constant Summary collapse

VERSION = 
'2.1.7'.freeze

Class Method Summary collapse

Class Method Details

.column_of(table_name, column_name) ⇒ Object 



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# File 'lib/arel_extensions/helpers.rb', line 27

def self.column_of(table_name, column_name)
  pool = ActiveRecord::Base.connection.pool
  use_arel_table = !ActiveRecord::Base.connected? || \
    (pool.respond_to?(:schema_cache) && pool.schema_cache.nil?)

  if use_arel_table
    column_of_via_arel_table(table_name, column_name)
  else
    if pool.respond_to?(:pool_config)
      pool.pool_config.schema_cache.columns_hash(table_name)[column_name]
    elsif pool.respond_to?(:schema_cache)
      pool.schema_cache.columns_hash(table_name)[column_name]
    else
      column_of_via_arel_table(table_name, column_name)
    end
  end
rescue ActiveRecord::ConnectionNotEstablished
  column_of_via_arel_table(table_name, column_name)
rescue ActiveRecord::StatementInvalid
  nil
rescue => e
  warn("Warning: Unexpected exception caught while fetching column name for #{table_name}.#{column_name} in `column_of`\n#{e.class}: #{e}")
  nil
end

.column_of_via_arel_table(table_name, column_name) ⇒ Object

column_of

Before the creation of these methods, getting the column name was done uniquely through the code found in ‘column_of_via_arel_table`.

This turned out to be unreliable, most notably when using adapters that do not come with activerecord standard batteries. SQL Server is the most notorious example.

Currently, we’re using a needlessly complicated way to address this issue. Different versions of activerecord are behaving differently; the public APIs do not seem to come with any guarantees, so we need to be sure that we’re coveing all these cases.



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# File 'lib/arel_extensions/helpers.rb', line 18

def self.column_of_via_arel_table(table_name, column_name)
  Arel::Table.engine.connection.schema_cache.columns_hash(table_name)[column_name]
rescue NoMethodError
  nil
rescue => e
  warn("Warning: Unexpected exception caught while fetching column name for #{table_name}.#{column_name} in `column_of_via_arel_table`\n#{e.class}: #{e}")
  nil
end