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Logging
Overview
Komapper outputs log messages related to SQL and transactions.
The default output destination is standard output, but it can be changed.
Log categories
Komapper has four log categories, as follows:
- org.komapper.Sql
- org.komapper.SqlWithArgs
- org.komapper.Transaction
- org.komapper.Other
org.komapper.Sql
In the org.komapper.Sql category, SQL statements with bind variables are output at the DEBUG level:
insert into ADDRESS (STREET, VERSION, CREATED_AT, UPDATED_AT) values (?, ?, ?, ?)
select t0_.ADDRESS_ID, t0_.STREET, t0_.VERSION, t0_.CREATED_AT, t0_.UPDATED_AT from ADDRESS as t0_ where t0_.ADDRESS_ID = ?
org.komapper.SqlWithArgs
In the org.komapper.SqlWithArgs category,
SQL statements in which bind variables are resolved with arguments are output at the TRACE level:
insert into ADDRESS (STREET, VERSION, CREATED_AT, UPDATED_AT) values ('street A', 0, '2021-07-31T21:23:24.511', '2021-07-31T21:23:24.511')
select t0_.ADDRESS_ID, t0_.STREET, t0_.VERSION, t0_.CREATED_AT, t0_.UPDATED_AT from ADDRESS as t0_ where t0_.ADDRESS_ID = 1
org.komapper.Transaction
In the org.komapper.Transaction category,
messages indicating transaction beginning, commit, and rollback are output at the TRACE level:
Begin: JdbcTransaction(id=032d9623-919f-43d4-ad00-f7d4c1518393, name=null)
Rollback: JdbcTransaction(id=032d9623-919f-43d4-ad00-f7d4c1518393, name=null)
Begin: JdbcTransaction(id=a108b824-3353-475c-a29b-cb1575951803, name=null)
Commit: JdbcTransaction(id=a108b824-3353-475c-a29b-cb1575951803, name=null)
org.komapper.Other
In the org.komapper.Other category, any message will be output at any log level.
Use of LoggerFacade
To change log messages and log levels, create your LoggerFacade implementation.
Example configuration for changing SQL log level
For example, if you want to change the SQL log level from DEBUG to INFO,
create an implementation class for LoggerFacade and its factory class as follows:
package example
import org.komapper.core.DefaultLoggerFacade
import org.komapper.core.LogCategory
import org.komapper.core.Logger
import org.komapper.core.LoggerFacade
import org.komapper.core.Statement
import org.komapper.core.StatementPart
import org.komapper.core.spi.LoggerFacadeFactory
class MyLoggerFacade(private val logger: Logger) : LoggerFacade by DefaultLoggerFacade(logger) {
override fun sql(statement: Statement, format: (Int, StatementPart.Value) -> CharSequence) {
logger.info(LogCategory.SQL) {
statement.toSql(format)
}
}
}
class MyLoggerFacadeFactory : LoggerFacadeFactory {
override fun create(logger: Logger): LoggerFacade {
return MyLoggerFacade(logger)
}
}
Then, create a file “org.komapper.core.spi.LoggerFacadeFactory” in the directory “src/main/resource/META-INF/services” and add the fully qualified name of the above factory class to the file.
Use of SLF4J
To use SLF4J as a logging library, include the komapper-slf4j module in the Gradle dependency declaration:
val komapperVersion: String by project
dependencies {
runtimeOnly("org.komapper:komapper-slf4j:$komapperVersion")
}
Also, if Logback is used as an implementation of SLF4J, the logback-classic module should be included in the dependency declaration:
val komapperVersion: String by project
dependencies {
runtimeOnly("org.komapper:komapper-slf4j:$komapperVersion")
runtimeOnly("ch.qos.logback:logback-classic:1.2.5")
}
Note
The above dependency declaration is not necessary when using Starters.Example configuration for SQL logging with Logback
Place the following logback.xml under src/main/resources:
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
</encoder>
</appender>
<logger name="org.komapper.Sql" level="debug"/>
<root level="info">
<appender-ref ref="STDOUT" />
</root>
</configuration>
In the above example, the log category org.komapper.Sql is used.
Instead, to use the log category org.komapper.SqlWithArgs, write as follows:
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%logger{36} - %msg%n</pattern>
</encoder>
</appender>
<logger name="org.komapper.SqlWithArgs" level="trace"/>
<root level="info">
<appender-ref ref="STDOUT" />
</root>
</configuration>