Do not try query when values is empty

Stephen Paul Weber created 4 years ago

If there are no values to query with, then the SQL will be invalid and throw an
error, so just return empty for that case.

Change summary

config.ru | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

Detailed changes

config.ru

@@ -170,16 +170,23 @@ end
 
 class UnknownTransactions
 	def self.from(customer_id, address, tx_hashes)
+		self.for(
+			customer_id,
+			fetch_rows_for(address, tx_hashes).map { |row| row["transaction_id"] }
+		)
+	end
+
+	def self.fetch_rows_for(address, tx_hashes)
 		values = tx_hashes.map do |tx_hash|
 			"('#{DB.escape_string(tx_hash)}/#{DB.escape_string(address)}')"
 		end
-		rows = DB.exec_params(<<-SQL)
+		return [] unless values
+		DB.exec_params(<<-SQL)
 			SELECT transaction_id FROM
 				(VALUES #{values.join(',')}) AS t(transaction_id)
 				LEFT JOIN transactions USING (transaction_id)
 			WHERE transactions.transaction_id IS NULL
 		SQL
-		self.for(customer_id, rows.map { |row| row["transaction_id"] })
 	end
 
 	def self.for(customer_id, transaction_ids)