Package org.springframework.data.cassandra.core.cql

Interface SessionCallback<T>

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface SessionCallback<T>

Generic callback interface for code that operates on a Cassandra CqlSession. Allows to execute any number of operations on a single session, using any type and number of statements.

This is particularly useful for delegating to existing data access code that expects a CqlSession to work on and throws DriverException. For newly written code, it is strongly recommended to use CqlTemplate's more specific operations, for example a query or update variant.

Author:

David Webb, Mark Paluch

See Also:

• CqlTemplate.execute(SessionCallback)
• CqlTemplate.query(java.lang.String, org.springframework.data.cassandra.core.cql.ResultSetExtractor<T>)
• CqlTemplate.execute(String)

Method Summary

Modifier and Type	Method	Description
T	doInSession(com.datastax.oss.driver.api.core.CqlSession session)	Gets called by CqlTemplate.execute(org.springframework.data.cassandra.core.cql.SessionCallback<T>) with an active Cassandra CqlSession.

Method Details

doInSession

T doInSession(com.datastax.oss.driver.api.core.CqlSession session)
       throws com.datastax.oss.driver.api.core.DriverException,
DataAccessException

Gets called by CqlTemplate.execute(org.springframework.data.cassandra.core.cql.SessionCallback<T>) with an active Cassandra CqlSession. Does not need to care about activating or closing the CqlSession.

Allows for returning a result object created within the callback, i.e. a domain object or a collection of domain objects. Note that there's special support for single step actions: see CqlTemplate.queryForObject(java.lang.String, java.lang.Class<T>) etc. A thrown RuntimeException is treated as application exception: it gets propagated to the caller of the template.

Parameters:

session - active Cassandra Session, must not be null.

Returns:

a result object, or null if none.

Throws:

com.datastax.oss.driver.api.core.DriverException - if thrown by a Session method, to be auto-converted to a DataAccessException.

DataAccessException - in case of custom exceptions.

See Also:

• CqlTemplate.queryForObject(String, Class)
• CqlTemplate.queryForResultSet(String)