Package org.pjdbc.drivers

Class FilterDriver

java.lang.Object

org.pjdbc.sql.AbstractDriver

org.pjdbc.sql.AbstractProxyDriver

org.pjdbc.drivers.FilterDriver

All Implemented Interfaces:

Driver

@DriverCapability(prefix="filter",
                  description="Transforms SQL statements using built-in or custom transformers",
                  capabilities={"transformation","filtering"})
@DriverParameter(name="class",type=STRING,description="Fully qualified class name of custom JdbcTransformer implementation") @DriverParameter(name="schema",type=STRING,description="Schema prefix to add to unqualified table names") @DriverParameter(name="where",type=STRING,description="Condition to append to WHERE clauses (e.g., deleted=false)") @DriverParameter(name="rename.*",type=STRING,description="Rename identifiers: rename.OLD_NAME=NEW_NAME")
public class FilterDriver
extends AbstractProxyDriver

FilterDriver transforms SQL statements using configurable transformers.

Built-in Transformers

URL-configurable transformers for common use cases:

Schema Prefix

Add schema prefix to unqualified table names:

 jdbc:filter[schema=tenant_123]:jdbc:postgresql://localhost/db
 -- SELECT * FROM users → SELECT * FROM tenant_123.users
 

WHERE Clause

Append condition to all SELECT/UPDATE/DELETE statements:

 jdbc:filter[where=deleted=false]:jdbc:mysql://localhost/db
 -- SELECT * FROM users → SELECT * FROM users WHERE deleted=false
 -- SELECT * FROM users WHERE active=true → SELECT * FROM users WHERE active=true AND deleted=false
 

Rename Identifiers

Rename table or column names (case-insensitive):

 jdbc:filter[rename.old_table=new_table]:jdbc:h2:mem:test
 jdbc:filter[rename.users=customers,rename.created=created_at]:jdbc:...
 

Combining Transformers

Multiple transformers are applied in order:

 jdbc:filter[schema=acme,where=active=true,rename.old=new]:jdbc:...
 

Custom Transformer Class

For complex transformations, specify a custom transformer class:

 jdbc:filter[class=com.example.MyTransformer]:jdbc:postgresql://localhost/db
 

The transformer class must implement JdbcTransformer and have a no-argument constructor.

Per-Connection Transformers

Each connection gets its own transformer instance. This ensures thread-safety and predictable behavior in connection-pooled environments.

See Also:

• JdbcTransformer
• AbstractJdbcTransformer
• SchemaTransformer
• WhereTransformer
• RenameTransformer

Driver Parameters

URL format: jdbc:filter[param=value,...]:<target-url>

Parameter	Type	Default	Constraints	Description
class	string	-	-	Fully qualified class name of custom JdbcTransformer implementation
schema	string	-	-	Schema prefix to add to unqualified table names
where	string	-	-	Condition to append to WHERE clauses (e.g., deleted=false)
rename.*	string	-	-	Rename identifiers: rename.OLD_NAME=NEW_NAME

Field Summary

Fields

Modifier and Type	Field	Description
protected ThreadLocal<JdbcTransformer>	transformer	Deprecated. Use URL parameter class= instead.

Constructor Summary

Constructors

Constructor	Description
FilterDriver()

Method Summary

Modifier and Type	Method	Description
protected boolean	acceptsSubProtocol(String subprotocol)
Connection	connect(String url, Properties info)
JdbcTransformer	getTransformer()	Deprecated. Use URL parameter class= instead.
protected Connection	proxyConnection(Connection delegate, String url, Properties info, Driver driver)
protected Statement	proxyStatement(Statement delegate, Connection conn)
void	setTransformer(JdbcTransformer transformer)	Deprecated. Use URL parameter class= instead: jdbc:filter[class=com.example.MyTransformer]:jdbc:...

Methods inherited from class org.pjdbc.sql.AbstractProxyDriver

acceptsSubName, getPropertyInfo, isCompositionValidationEnabled, isValidateParametersEnabled, proxyCallableStatement, proxyCallableStatement, proxyConnection, proxyConnection, proxyPreparedStatement, proxyPreparedStatement, proxyResultSet

Methods inherited from class org.pjdbc.sql.AbstractDriver

acceptsProtocol, acceptsURL, getMajorVersion, getMinorVersion, getParentLogger, getUrlParameter, getUrlParameter, getUrlParameters, jdbcCompliant, parseUrl, protocol, subname, subprotocol, validateParameters

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

transformer

@Deprecated
protected ThreadLocal<JdbcTransformer> transformer

Deprecated.

Use URL parameter class= instead. This field will be removed in a future version.

ThreadLocal for backward compatibility with setTransformer() API.

Constructor Details

FilterDriver

public FilterDriver()

Method Details

acceptsSubProtocol

protected boolean acceptsSubProtocol(String subprotocol)

Specified by:

acceptsSubProtocol in class AbstractDriver

connect

public Connection connect(String url,
 Properties info)
                   throws SQLException

Specified by:

connect in interface Driver

Overrides:

connect in class AbstractProxyDriver

Throws:

SQLException

proxyConnection

protected Connection proxyConnection(Connection delegate,
 String url,
 Properties info,
 Driver driver)
                              throws SQLException

Overrides:

proxyConnection in class AbstractProxyDriver

Throws:

SQLException

proxyStatement

protected Statement proxyStatement(Statement delegate,
 Connection conn)
                            throws SQLException

Overrides:

proxyStatement in class AbstractProxyDriver

Throws:

SQLException

getTransformer

@Deprecated
public JdbcTransformer getTransformer()

Deprecated.

Use URL parameter class= instead. Per-thread transformers are confusing in pooled connection scenarios.

Get the current transformer for this thread.

Returns:

the JdbcTransformer used for SQL transformation, or null if not set

setTransformer

@Deprecated
public void setTransformer(JdbcTransformer transformer)

Deprecated.

Use URL parameter class= instead: jdbc:filter[class=com.example.MyTransformer]:jdbc:... Per-thread transformers cause confusion in pooled connection scenarios.

Set the transformer for SQL transformation for this thread.

Parameters:

transformer - the JdbcTransformer to use