[Zope] How do I check for existence of a page?

[Dieter Maurer]

You should not use a "dtml-in" to check for the existence of
an object. You should directly check for the object:

  I many cases, you can use

    <dtml-if "_.hasattr(aq_explicit,'attrname')">

  or

    <dtml-if "_.hasattr(object.aq_explicit,'attrname')">

  to check whether the current object or "object", respectively,
  has attribute "attrname".


  In some rare cases, this can give you a "true" result,
  even though the object does not have an 'attrname'.

  A save way is an external method "baseHasAttr" defined by

    def baseHasAttr(object,attrname):
      obj= getattr(object,aq_base,object)
      return hasattr(obj,attrname)

  and a test through

      <dtml-if "baseHasAttr(this(),'attrname')>
  or
      <dtml-if "baseHasAttr(object,'attrname')>


Dieter