Package freemarker.template

Interface MethodCallAwareTemplateHashModel

All Superinterfaces:

TemplateHashModel, TemplateModel

All Known Implementing Classes:

GenericObjectModel

public interface MethodCallAwareTemplateHashModel
extends TemplateHashModel

Adds an extra getter method to TemplateHashModel that can return different result than TemplateHashModel.get(String), knowing that the result of it will be called as a method. At least as of 2.3.33, this is only used by the template language for 0-argument method calls that are directly after the dot operator and the key (like in obj.m(), where the "()" is directly after the key "m"), or for the equivalent of that with square brackets (obj["m"]()).

Background knowledge needed to understand this: In the FreeMarker template language, methods/functions are first class values (just like strings, numbers,etc.). Also, unlike in Java, there's no separate namespace for methods, and for the other field-like members. When you have obj.m() in a template, first, the dot operator gets the value for the key "m", and after that, and independently of that, the method call operator tries to call that value (and if it's not a method or function, that will fail). The dot operator, before 2.3.33, was never aware of what the value it gets will be used for (like will it be called, will it be printed, etc.). Now it can be. For example, if in the template you have someRecord.someComponent(), and there someRecord was wrapped by the ObjectWrapper into a TemplateHashModel that also implements this interface, then the dot operator will call getBeforeMethodCall("someComponent"), rather than get("someComponent"). This is needed to implement subtle features like BeansWrapper.MethodAppearanceDecision.setMethodInsteadOfPropertyValueBeforeCall(boolean), which is needed to implement ZeroArgumentNonVoidMethodPolicy.BOTH_METHOD_AND_PROPERTY_UNLESS_BEAN_PROPERTY_READ_METHOD.

While technically we could do the same for method calls with more the 0 arguments, as of 2.3.33 at least, we don't want to generalize this to that case. This is a workaround we added to address the issue with accessing components in Java records, which are 0-argument methods (see that at BeansWrapper.MethodAppearanceDecision.setMethodInsteadOfPropertyValueBeforeCall(boolean)).

Objects wrapped with BeansWrapper, and hence with DefaultObjectWrapper, will implement this interface when they are "generic" objects (that is, when they are not classes with special wrapper, like Map-s, Collection-s, Number-s, etc.).

Since:

2.3.33

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	MethodCallAwareTemplateHashModel.ShouldNotBeGetAsMethodException	Thrown by getBeforeMethodCall(String); see there.

Field Summary

Fields inherited from interface freemarker.template.TemplateModel

NOTHING

Method Summary

Modifier and Type	Method	Description
TemplateModel	getBeforeMethodCall(String key)	This is called instead of TemplateHashModel.get(String) if we know that the return value should be callable like a method.

Methods inherited from interface freemarker.template.TemplateHashModel

get, isEmpty

Method Details

getBeforeMethodCall

TemplateModel getBeforeMethodCall(String key)
                           throws TemplateModelException,
MethodCallAwareTemplateHashModel.ShouldNotBeGetAsMethodException

This is called instead of TemplateHashModel.get(String) if we know that the return value should be callable like a method. The advantage of this is that we can coerce the value to a method when desirable, and otherwise can give a more specific error message in the resulting exception than the standard NonMethodException would.

Parameters:

key - Same as for TemplateHashModel.get(String)

Returns:

Same as for TemplateHashModel.get(String), except it should return a TemplateMethodModel (a TemplateMethodModelEx if possible), or in very rare case a Macro that was created with the function directive. Or, null in the same case as TemplateHashModel.get(String). The method should never return something that's not callable in the template language as a method or function; the return type is TemplateModel because that's the most specific common super-interface of TemplateMethodModel, and Macro.

Throws:

MethodCallAwareTemplateHashModel.ShouldNotBeGetAsMethodException - If the value for the given key exists, but shouldn't be coerced to something callable as a method. This will be converted to NonMethodException by the engine, but in this exception you can optionally give a more specific explanation, and that will be added to the resulting NonMethodException as a hint to the user.

TemplateModelException