Hibernate
/
hibernate-orm
mirror of https://github.com/hibernate/hibernate-orm
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

slightly expand the documentation for Boolean

This commit is contained in:
Gavin King 2021-12-12 01:11:47 +01:00 committed by Steve Ebersole
parent 863802cfd0
commit 7a81ec78ff
1 changed files with 18 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
documentation/src/main/asciidoc/userguide/chapters/domain/basic_types.adoc
View File

@ -399,8 +399,9 @@ For additional details on using custom types, see <<basic-mapping-custom>> secti
[[basic-boolean]]
==== Boolean
Boolean values in the domain model are generally mapped to BOOLEAN/BIT on the database side depending on the
database's capabilities.
By default, `Boolean` attributes map to `BOOLEAN` columns, at least when the database has a
dedicated `BOOLEAN` type. On databases which don't, Hibernate uses whatever else is available:
`BIT`, `TINYINT`, or `SMALLINT`.
[[basic-boolean-example-implicit]]
.Implicit boolean mapping
@ -411,9 +412,19 @@ include::{sourcedir}/basic/BooleanMappingTests.java[tags=basic-boolean-example-i
----
====
However, it is certainly reasonable to map booleans to other representations in the
database and Hibernate provides support for mapping booleans to the more well known
representations - 'Y' / 'N', 'T' / 'F' or 1 (true) / 0 (false).
But, especially when working with a legacy database, it's quite common to find boolean values
encoded as a character, or as an integer, even when the platform _does_ support a built-in
`BOOLEAN` type.
The easiest way to handle this situation is to use a JPA `AttributeConverter`. You can easily
write your own `AttributeConverter`, but for your convenience, Hibernate comes with three
built-in converters for common cases:
- `YesNoConverter` encodes a boolean value as `'Y'` or `'N'`,
- `TrueFalseConverter` encodes a boolean value as `'T'` or `'F'`, and
- `NumericBooleanConverter` encodes the value as an integer, `1` for true, and `0` for false.
You may specify the converter to use with the `@Convert` annotation.
[[basic-boolean-example-converted]]
.Using `AttributeConverter`
@ -428,11 +439,8 @@ include::{sourcedir}/basic/BooleanMappingTests.java[tags=basic-boolean-example-e
----
====
Here the built-in `AttributeConverter` implementations provided by Hibernate are used. A custom
`AttributeConverter` could be used also.
Booleans can also be mapped using `UserType` and `@CustomType`
Of course, if you need to do something really special, a boolean value can also be mapped using
`@CustomType` and your own `UserType`.
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~