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Improving the documentation.

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See #908
Original pull request #983
This commit is contained in:
Jens Schauder
2021-06-02 11:56:49 +02:00
committed by Mark Paluch
parent 4c6894464e
commit c3e21cc799
2 changed files with 22 additions and 47 deletions
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26
src/main/asciidoc/jdbc-custom-conversions.adoc
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@@ -1,4 +1,6 @@
[[jdbc.custom-converters]]
// for backward compatibility only:
[[jdbc.entity-persistence.custom-converters]]
== Custom Conversions
Spring Data JDBC allows registration of custom converters to influence how values are mapped in the database.
@@ -55,12 +57,26 @@ class MyJdbcConfiguration extends AbstractJdbcConfiguration {
// …
@Overwrite
@Bean
public JdbcCustomConversions jdbcCustomConversions() {
return new JdbcCustomConversions(Arrays.asList(new BooleanToStringConverter(), new StringToBooleanConverter()));
}
@Override
protected List<?> userConverters() {
return Arrays.asList(new BooleanToStringConverter(), new StringToBooleanConverter());
}
}
----
NOTE: In previous versions of Spring Data JDBC it was recommended to directly overwrite `AbstractJdbcConfiguration.jdbcCustomConversions()`.
This is no longer necessary or even recommended, since that method assembles conversions intended for all databases, conversions registered by the `Dialect` used and conversions registered by the user.
If you are migrating from an older version of Spring Data JDBC and have `AbstractJdbcConfiguration.jdbcCustomConversions()` overwritten conversions from your `Dialect` will not get registered.
[[jdbc.custom-converters.jdbc-value]]
// for backward compatibility only:
[[jdbc.entity-persistence.custom-converters.jdbc-value]]
=== JdbcValue
Value conversion uses `JdbcValue` to enrich values propagated to JDBC operations with a `java.sql.Types` type.
Register a custom write converter if you need to specify a JDBC-specific type instead of using type derivation.
This converter should convert the value to `JdbcValue` which has a field for the value and for the actual `JDBCType`.
include::{spring-data-commons-docs}/custom-conversions.adoc[leveloffset=+3]

43
src/main/asciidoc/jdbc.adoc
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@@ -263,48 +263,7 @@ p1.bestFriend = AggregateReference.to(p2.id);
----
====
[[jdbc.entity-persistence.custom-converters]]
=== Custom converters
Custom converters can be registered, for types that are not supported by default, by inheriting your configuration from `AbstractJdbcConfiguration` and overwriting the method `jdbcCustomConversions()`.
====
[source,java]
----
@Configuration
class DataJdbcConfiguration extends AbstractJdbcConfiguration {
@Override
public JdbcCustomConversions jdbcCustomConversions() {
return new JdbcCustomConversions(Collections.singletonList(TimestampTzToDateConverter.INSTANCE));
}
@ReadingConverter
enum TimestampTzToDateConverter implements Converter<TIMESTAMPTZ, Date> {
INSTANCE;
@Override
public Date convert(TIMESTAMPTZ source) {
//...
}
}
}
----
====
The constructor of `JdbcCustomConversions` accepts a list of `org.springframework.core.convert.converter.Converter`.
Converters should be annotated with `@ReadingConverter` or `@WritingConverter` in order to control their applicability to only reading from or to writing to the database.
`TIMESTAMPTZ` in the example is a database specific data type that needs conversion into something more suitable for a domain model.
[[jdbc.entity-persistence.custom-converters.jdbc-value]]
==== JdbcValue
Value conversion uses `JdbcValue` to enrich values propagated to JDBC operations with a `java.sql.Types` type.
Register a custom write converter if you need to specify a JDBC-specific type instead of using type derivation.
This converter should convert the value to `JdbcValue` which has a field for the value and for the actual `JDBCType`.
* Types for which you registered suitable [[jdbc.custom-converters, custom conversions]].
[[jdbc.entity-persistence.naming-strategy]]
=== `NamingStrategy`