Grails error while connecting mysql

Question

i am getting following error while connecting to mysql

i have copied mysql-connector-java-5.1.22-bin.jar to lib folder in my application

| Error 2012-11-26 16:14:16,981 [localhost-startStop-1] ERROR context.GrailsContextLoader  - Error executing bootstraps: Error creating bean with name 'transactionManagerPostProcessor': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
Message: Error creating bean with name 'transactionManagerPostProcessor': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
    Line | Method
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread

Caused by BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread

Caused by BeanCreationException: Error creating bean with name 'sessionFactory': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread

Caused by BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread

Caused by BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread

Caused by MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread

Caused by SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
->> 1429 | createConnectionFactory in org.apache.commons.dbcp.BasicDataSource
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|   1371 | createDataSource in     ''
|   1044 | getConnection in     ''
|    334 | innerRun  in java.util.concurrent.FutureTask$Sync
|    166 | run . . . in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run       in java.lang.Thread

Caused by ClassNotFoundException: com.mysql.jdbc.Driver
->>  366 | run       in java.net.URLClassLoader$1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    355 | run       in     ''
|    354 | findClass in java.net.URLClassLoader
|    423 | loadClass in java.lang.ClassLoader
|    356 | loadClass in     ''
|   1420 | createConnectionFactory in org.apache.commons.dbcp.BasicDataSource
|   1371 | createDataSource in     ''
|   1044 | getConnection in     ''
|    334 | innerRun  in java.util.concurrent.FutureTask$Sync
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread

Answer 1

You shouldn't copy the jar file into the lib directory when it's available in a Maven repository - it's better to download it once and cache it instead of having multiple copies, one in each of your projects. In fact the MySQL driver is the example we use in the generated BuildConfig.groovy. Just uncomment it and update the version:

dependencies {
   runtime 'mysql:mysql-connector-java:5.1.22'
}

If you do have a jar file that's not in a Maven repo, put it in your lib directory. But Grails doesn't automatically discover it, so you need to run grails compile --refresh-dependencies