/**
* Resolves the expression of an empty blob based on the configuration or if it is not available
* in the configuration, based on the database type.
*
* @param configuration The configuration that was passed to the blobstore.
* @return The expression of an empty blob that can be used in an insert statement.
*/
protected Expression<Blob> resolveEmptyBlobExpression(
final JdbcBlobstoreConfiguration configuration) {
if (configuration != null && configuration.emptyBlobExpression != null) {
return configuration.emptyBlobExpression;
}
DatabaseTypeEnum databaseType = guessDatabaseType();
if (databaseType == DatabaseTypeEnum.ORACLE) {
return SQLExpressions.relationalFunctionCall(Blob.class, "empty_blob");
} else {
return Expressions.constant(new EmptyReadOnlyBlob());
}
}
/**
* Resolving the selection expression of the blob based on the configuration or if it is not
* available in the configuration, based on the database type. This is necessary as for example if
* MySQL is used with remote locator mode, instead of the blob column name, a string constant has
* to be used that contains the column name in the SQL expression.
*
* @param configuration The configuration passed to this blobstore.
* @return The selection expression of the blob.
*/
protected Expression<?> resolveBlobSelectionExpression(
final JdbcBlobstoreConfiguration configuration) {
if (configuration != null && configuration.blobSelectionExpression != null) {
return configuration.blobSelectionExpression;
}
DatabaseTypeEnum databaseType = guessDatabaseType();
if (databaseType != DatabaseTypeEnum.MYSQL) {
return QBlobstoreBlob.blobstoreBlob.blob_;
}
try (Connection connection = dataSource.getConnection()) {
if (!connection.getMetaData().locatorsUpdateCopy()) {
return Expressions.constant(QBlobstoreBlob.blobstoreBlob.blob_.getMetadata().getName());
} else {
return QBlobstoreBlob.blobstoreBlob.blob_;
}
} catch (SQLException e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
}
