[CSV-93] Allow the handling of NULL values

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0
• Fix Version/s: 1.9.0
• Component/s: Documentation, Parser, Printer
• Assignee: Unassigned
• Reporter: Georg Tsakumagos
• Created: 30/Jul/12 10:01
• Updated: 08/Jul/21 16:37
• Resolved: 08/Jul/21 16:37

Description

Requirement

To use the CSV parser and printer for SQL Dumps it would be nice if they could handle null values.

Specification

To distinguish between an empty or null value empty values always gets quoted to denote an empty string. The absence of an quote denotes a null value

Configuration

To activate the behavior call the method withNullObjectPatternEnabled of the CSVFormat with parameter true.

Modifications

See attached patch.

Example

This example using as base the DEFAULT CSVFormat modified by the NullObjectPattern behavior.

Array-Data	CSV-Data
{null,"","A"," "};	,"A",""," "
{"",null,"A"," "}	"",,"A"," "
{"","A",null}	"","A",

NULL in DBMS proprietary CSV formats

Product	Strategy	Documentation / Link
PostgreSQL	If NULL should be preserved all non NULL values gets quoted	PostgreSQL 8.1 Manual
MySQL	NULL Values will be replaced by the letters NULL or escaped by \n	not found, verified with MySQL Workbench
MS SQL	NULL values will be exported as empty strings (no quotes). Strings will be quoted if needed. Import can interpret them as null	MSDN
Oracle	NULL Values will be replaced by the letters NULL	Manual

Issue Links

• is related to: CSV-203 withNullString value is printed without quotes when QuoteMode.ALL is specified; add QuoteMode.ALL_NON_NULL
• is related to: CSV-253 Handle absent values in input (null)
• is required by: CSV-64 CSVPrinter does not distinguish null and the empty string