Class: Tina4::Drivers::PostgresDriver

Inherits:
Object
  • Object
show all
Defined in:
lib/tina4/drivers/postgres_driver.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#connection ⇒ Object (readonly)

Returns the value of attribute connection.



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# File 'lib/tina4/drivers/postgres_driver.rb', line 6

def connection
  @connection
end

Instance Method Details

#apply_limit(sql, limit, offset = 0) ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 99

def apply_limit(sql, limit, offset = 0)
  "#{sql} LIMIT #{limit} OFFSET #{offset}"
end

#begin_transaction ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 103

def begin_transaction
  @connection.exec("BEGIN")
end

#close ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 27

def close
  @connection&.close
end

#columns(table_name) ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 121

def columns(table_name)
  sql = "SELECT column_name, data_type, is_nullable, column_default FROM information_schema.columns WHERE table_name = $1"
  rows = execute_query(sql, [table_name])
  rows.map do |r|
    {
      name: r[:column_name],
      type: r[:data_type],
      nullable: r[:is_nullable] == "YES",
      default: r[:column_default],
      primary_key: false
    }
  end
end

#commit ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 107

def commit
  @connection.exec("COMMIT")
end

#connect(connection_string, username: nil, password: nil) ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 8

def connect(connection_string, username: nil, password: nil)
  begin
    require "pg"
  rescue LoadError
    raise LoadError,
          "The 'pg' gem is required for PostgreSQL connections. Install one of:\n" \
          "    bundle add pg     # if your project uses Bundler\n" \
          "    gem install pg    # bare driver"
  end
  url = connection_string
  if username || password
    uri = URI.parse(url)
    uri.user = username if username
    uri.password = password if password
    url = uri.to_s
  end
  @connection = PG.connect(url)
end

#execute(sql, params = []) ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 41

def execute(sql, params = [])
  converted_sql = convert_placeholders(sql)
  if params.empty?
    @connection.exec(converted_sql)
  else
    @connection.exec_params(converted_sql, params)
  end
end

#execute_query(sql, params = []) ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 31

def execute_query(sql, params = [])
  converted_sql = convert_placeholders(sql)
  result = if params.empty?
             @connection.exec(converted_sql)
           else
             @connection.exec_params(converted_sql, params)
           end
  result.map { |row| decode_blobs(symbolize_keys(row)) }
end

#last_insert_id ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 50

def last_insert_id
  # Issue #38: ``SELECT lastval()`` raises on tables with no sequence
  # (UUID, ULID, hash PKs etc.). The exception itself isn't fatal,
  # but the pg gem marks the whole transaction as aborted, so every
  # subsequent statement on this connection fails with
  # ``PG::InFailedSqlTransaction`` — far away from the real cause.
  #
  # Fix: wrap the probe in a SAVEPOINT. If ``lastval()`` raises, we
  # ROLLBACK TO SAVEPOINT and the outer transaction stays usable;
  # ``last_insert_id`` just returns ``nil`` (same as before for
  # tables without a sequence). On success we RELEASE SAVEPOINT.
  begin
    @connection.exec("SAVEPOINT _t4_lastval_probe")
  rescue PG::Error
    # No active transaction (autocommit/idle) — fall back to a plain
    # probe; psycopg2-style transaction abort can't happen here.
    begin
      result = @connection.exec("SELECT lastval()")
      return result.first["lastval"].to_i
    rescue PG::Error
      return nil
    end
  end

  begin
    result = @connection.exec("SELECT lastval()")
    @connection.exec("RELEASE SAVEPOINT _t4_lastval_probe")
    result.first["lastval"].to_i
  rescue PG::Error
    begin
      @connection.exec("ROLLBACK TO SAVEPOINT _t4_lastval_probe")
      @connection.exec("RELEASE SAVEPOINT _t4_lastval_probe")
    rescue PG::Error
      # If even the rollback fails, there's nothing we can do — the
      # connection is in a state we can't recover. Surface nil so
      # callers don't get a half-set last_id.
    end
    nil
  end
end

#placeholder ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 91

def placeholder
  "?"
end

#placeholders(count) ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 95

def placeholders(count)
  (1..count).map { |i| "$#{i}" }.join(", ")
end

#rollback ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 111

def rollback
  @connection.exec("ROLLBACK")
end

#tables ⇒ Object 



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# File 'lib/tina4/drivers/postgres_driver.rb', line 115

def tables
  sql = "SELECT tablename FROM pg_tables WHERE schemaname = 'public'"
  rows = execute_query(sql)
  rows.map { |r| r[:tablename] }
end