# Package org.apache.cayenne.exp

Cayenne data expression classes.

This package contains classes that describe expression language of Cayenne. Cayenne expressions define expressions on objects rather than expressions on data. Other parts of Cayenne may translate them to the target database SQL syntax.

- Interface Summary
  Interface | Description
  --- | ---
  TraversalHandler | Expression visitor interface.
  ValueInjector | Describes expressions, that can "inject" value to an object, i.e.

- Class Summary
  Class | Description
  --- | ---
  Expression | Superclass of Cayenne expressions that defines basic API for expressions use.
  ExpressionFactory | Helper class to build expressions.
  ExpressionParameter | Named parameter for parameterized expressions.
  FunctionExpressionFactory | Collection of factory methods to create function call expressions.
  Property<E> | Deprecated. since 4.2 in favour of type-specific set of properties, see `PropertyFactory` and `org.apache.cayenne.exp.property` package.
  TraversalHelper | Noop implementation of TraversalHandler.

- Exception Summary
  Exception | Description
  --- | ---
  ExpressionException | RuntimeException thrown on errors during expressions creation/parsing.