[Erp5-dev] [patch] Fixing API of Field.render_view and Widget.render_view

[Julien Muchembled]

Contrary to {Field,Widget}.render, render_view doesn't take a REQUEST parameter and there are cases where this prevents from accessing 'cell' in TALES. For example:

Let's suppose you have a ListBox with an editable column but you want certain fields not to be editable (by writing a TALES expression for the 'editable' property of the field). If the field is not editable, cell can't be accessed for properties like 'items', and you must write hacks like :
some_expression_will_cell | some_expression_without_cell_that_will_always_contain_the_current_value

What happens:

The behaviour of a listbox is the same for an editable field and a non-editable one so ListBox.py seems ok. In both cases, the following lines are executed:

2136            cell_request = brain.asContext( REQUEST = self.renderer.request
2137                                          , form    = self.renderer.request.form
2138                                          , cell    = brain
2139                                          )
2140            if editable_field.get_value('enabled', REQUEST=cell_request):
2141              cell_html = editable_field.render( \
2142                                value   = display_value
2143                              , REQUEST = cell_request
2144                              , key     = key
2145                              )
2146            else:
2147              cell_html = ''

with cell_request.cell == brain != None

Then, we have the following calls chain:

* editable field:
  File "/home/jm/zope/1/Products/ERP5Form/ListBox.py", line 2150, in render
    , key     = key
  File "/home/jm/zope/1/Products/ERP5Form/FormulatorPatch.py", line 69, in Field_render
    return self._render_helper(self.generate_field_key(key=key), value, REQUEST)
  File "/home/jm/zope/1/Products/ERP5Form/FormulatorPatch.py", line 103, in Field_render_helper
    return self.widget.render(self, key, value, REQUEST)
  File "/home/jm/zope/1/Products/ERP5Form/ProxyField.py", line 75, in __call__
    return proxied_method(field, *args, **kw)
  File "/home/jm/zope/1/Products/ERP5Form/FormulatorPatch.py", line 735, in ListWidget_render
    rendered_items = self.render_items(field, key, value, REQUEST)
  File "/home/jm/zope/1/Products/ERP5Form/FormulatorPatch.py", line 587, in SingleItemsWidget_render_items
    items = field.get_value('items', REQUEST=REQUEST, cell=cell)
  File "/home/jm/zope/1/Products/ERP5Form/ProxyField.py", line 639, in get_value
    return ZMIField.get_value(self, id, **kw)
  File "/home/jm/zope/1/Products/ERP5Form/Form.py", line 298, in get_value
    return value(field, id, **kw)
  File "/home/jm/zope/1/Products/ERP5Form/Form.py", line 167, in __call__
    value = self.tales_expr.__of__(field)(**kw)

* non-éditable field:

  File "/home/jm/zope/1/Products/ERP5Form/ListBox.py", line 2145, in render
    , key     = key
  File "/home/jm/zope/1/Products/ERP5Form/FormulatorPatch.py", line 69, in Field_render
    return self._render_helper(self.generate_field_key(key=key), value, REQUEST)
  File "/home/jm/zope/1/Products/ERP5Form/FormulatorPatch.py", line 101, in Field_render_helper
    return self.widget.render_view(self, value)
  File "/home/jm/zope/1/Products/ERP5Form/ProxyField.py", line 75, in __call__
    return proxied_method(field, *args, **kw)
  File "/home/jm/zope/1/Products/ERP5Form/FormulatorPatch.py", line 755, in ListWidget_render_view
    title_list = [x[0] for x in field.get_value("items") if x[1]==value]
  File "/home/jm/zope/1/Products/ERP5Form/ProxyField.py", line 639, in get_value
    return ZMIField.get_value(self, id, **kw)
  File "/home/jm/zope/1/Products/ERP5Form/Form.py", line 294, in get_value
    return value(field, id, **kw)
  File "/home/jm/zope/1/Products/ERP5Form/Form.py", line 162, in __call__
    value = self.tales_expr.__of__(field)(**kw)

The difference is in FormulatorPatch.py, at line 101, where the call to render_view drops out RENDER=cell_request

A solution is to modify the API of render_view to be able to pass a REQUEST parameter, like render.


A strange thing is the comment before the call to brain.asContext (ListBox.py:2136):
    # to the field which is being displayed. Since the
    # render_view API did not permit this, we pass the line object
    # as the REQUEST. But this has side effects since it breaks
    # many possibilities. Therefore, the trick is to wrap
    # the REQUEST into the brain. In addition, the define a
    # cell property on the request itself so that forms may
    # use the 'cell' value (refer to get_value method in Form.py)

More precisely: « Since the render_view API did not permit this, we pass the line object as the REQUEST. »
Should we read 'render' instead of 'render_view' ?


The following patch fixes {Field,Widget}.render_view so that Listbox's non-editable cells can access 'cell' in TALES:

 * add a 'REQUEST' parameter to every render_view:
   * one more patch in FormulatorPatch to fix Field.render_view
   * for Field.render_view, default value for 'REQUEST' is None
   * for widgets, there is no default value
   * reorder parameters in OOoChartWidget.render_view
   * add a 'REQUEST' parameter to DurationField.render_sub_field_view
 * forward REQUEST to field.get_value in:
   * ListWidget_render_view (my goal)
   * TALESWidget_render_view (why not?)
 * PatchedLinkWidget.render_view and
   MultiRelationStringFieldWidget.render_view
   needn't call get_request anymore if REQUEST isn't None
 * PatchedLinkWidget.render_view: change REQUEST.get('cell') into
   getattr(REQUEST,'cell',None) since 'cell' may be an attribute of REQUEST


The patch doesn't break any test in ERP5Form/tests and in erp5_pdm_ui_test/erp5_ui_test.

A note about 
 * PatchedLinkWidget.render_view and
   MultiRelationStringFieldWidget.render_view
   needn't call get_request anymore if REQUEST isn't None
i.e.:
-    REQUEST = get_request()
+    if REQUEST is None:
+      REQUEST = get_request()

Perhaps we don't have to call get_request even if REQUEST is None. Not tested yet though.


JM
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