freemarker.template

Interface ObjectWrapperAndUnwrapper

All Superinterfaces:

ObjectWrapper

All Known Subinterfaces:

RichObjectWrapper

All Known Implementing Classes:

BeansWrapper, DefaultObjectWrapper, RhinoWrapper, SimpleObjectWrapper

public interface ObjectWrapperAndUnwrapper
extends ObjectWrapper

Experimental - subject to change: Adds functionality to ObjectWrapper that creates a plain Java object from a TemplateModel. This is usually implemented by ObjectWrapper-s and reverses ObjectWrapper.wrap(Object). However, an implementation of this interface should make a reasonable effort to "unwrap" TemplateModel-s that wasn't the result of object wrapping (such as those created directly in FTL), or which was created by another ObjectWrapper. The author of an ObjectWrapperAndUnwrapper should be aware of the TemplateModelAdapter and WrapperTemplateModel interfaces, which should be used for unwrapping if the TemplateModel implements them.

Experimental status warning: This interface is subject to change on non-backward compatible ways, hence, it shouldn't be implemented outside FreeMarker yet.

Since:

2.3.22

Field Summary

Fields

Modifier and Type	Field and Description
static Object	CANT_UNWRAP_TO_TARGET_CLASS Indicates that while the unwrapping is maybe possible, the result surely can't be the instance of the desired class, nor it can be null.

Fields inherited from interface freemarker.template.ObjectWrapper

BEANS_WRAPPER, DEFAULT_WRAPPER, SIMPLE_WRAPPER

Method Summary

Modifier and Type	Method and Description
Object	tryUnwrapTo(TemplateModel tm, Class targetClass) Attempts to unwrap a TemplateModel to a plain Java object that's the instance of the given class (or is null).
Object	unwrap(TemplateModel tm) Unwraps a TemplateModel to a plain Java object.

Methods inherited from interface freemarker.template.ObjectWrapper

wrap

Field Detail

CANT_UNWRAP_TO_TARGET_CLASS

static final Object CANT_UNWRAP_TO_TARGET_CLASS

Indicates that while the unwrapping is maybe possible, the result surely can't be the instance of the desired class, nor it can be null.

Since:

2.3.22

See Also:

tryUnwrapTo(TemplateModel, Class)

Method Detail

unwrap

Object unwrap(TemplateModel tm)
       throws TemplateModelException

Unwraps a TemplateModel to a plain Java object.

Returns:

The plain Java object. Can be null, if null is the appropriate Java value to represent the template model. null must not be used to indicate an unwrapping failure. It must NOT be CANT_UNWRAP_TO_TARGET_CLASS.

Throws:

TemplateModelException - If the unwrapping fails from any reason.

Since:

2.3.22

See Also:

tryUnwrapTo(TemplateModel, Class)

tryUnwrapTo

Object tryUnwrapTo(TemplateModel tm,
                   Class targetClass)
            throws TemplateModelException

Attempts to unwrap a TemplateModel to a plain Java object that's the instance of the given class (or is null).

Parameters:

targetClass - The class that the return value must be an instance of (except when the return value is null). Can't be null; if the caller doesn't care, it should either use {#unwrap(TemplateModel)}, or Object.class as the parameter value.

Returns:

The unwrapped value that's either an instance of targetClass, or is null (if null is the appropriate Java value to represent the template model), or is CANT_UNWRAP_TO_TARGET_CLASS if the unwrapping can't satisfy the targetClass (nor the result can be null). However, CANT_UNWRAP_TO_TARGET_CLASS must not be returned if the targetClass parameter was Object.class.

Throws:

TemplateModelException - If the unwrapping fails for a reason than doesn't fit the meaning of the CANT_UNWRAP_TO_TARGET_CLASS return value.

Since:

2.3.22

See Also:

unwrap(TemplateModel)