BeanEditor/PropertyEditor refactor for easy customization/extension
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Key: TAP5-886
URL: https://issues.apache.org/jira/browse/TAP5-886
Project: Tapestry 5
Issue Type: Improvement
Reporter: Giulio Micali
Priority: Minor
Problem Description:
This post is derived from my wish to write a custom improved BeanEditor
component, extending its behaviour to manage read-only properties, excluding
all attributes of one or more parent classes of my bean, ecc...
I tried to write that component, but I found that I should override(alias
duplicating) too many components/services involved in the process:
A) the BeanModelSource service:
I had overridden the createEditModel() in order to call create(beanClass,
false, messages); to view the read-only properties.
B) the BeanBlockSource service:
the "edit blocks" contains the editor, but also the label: the worst problem
stays here, forcing the layout of the container(BeanEditor or MyBeanEditor) in
a too much restricted way.
C) the propertyEditor:
this component gets the model from BeanModelSource and the (default)block to
render from BeanBlockSource:
- it doesn't know if a property is "read only", so if I override the
BeanModelSource to get read only properties, it cannot discriminate them and
render always a form control.
- the Block interface does not expose it's children list, so I cannot use a
dirty-workaround to remove the "label" component at rendering time
D) MyBeanEditor (obviously):
here I will rewrite the template, extend the original POJO with custom
modifications, ecc...
but to do so, I have to do the overrides described above.
Too many things to override.
Suggested Solution:
1) the BeanModelSource service
- the returned PropertyModel must have a boolean "writable" property, taken
from PropertyAdapter.isUpdate().
- the createEditModel() method is no longer useful, beanEditor must call
directly BeanModelSource.create(model, !BeanEditor.displayReadOnly, messages).
2) the BeanBlockSource service
- the "label" component must be detached from the "editor" block and should
have it's own block "<myProperty>Label" (like the grid component header) with
default value <t:label for="myEditor"/>
With that change, we can use propertyEditor inside other components(like grid
or custom components)
3) the propertyEditor:
- if a property is read-only, the editor (default)block will be taken from the
BeanDisplay-related blocks.
- (optional) can have a parameter "disabled" (tipically the BeanEditor can pass
it's own value): the value will "mark" at runtime the property as read-only,
overriding the value from BeanModel.
4) BeanEditor
the BeanEditor must:
- add a boolean parameter "displayReadOnly", which affects the call to
BeanModelSource.create(model, !displayReadOnly, messages);
- provide by itself the "label block" just like the BeanDisplay component(a
base class for that will be the best) getting it from the BeanBlockSource
service.
- if a property is read-only, the label block will be taken from the
BeanDisplay-related block.
- both label and editor block will be overridable just with the "overrides"
behaviour.
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