Mark,
On 2/17/21 04:08, Mark Thomas wrote:
On 16/02/2021 14:58, Christopher Schultz wrote:
All,
I'm sorry for using users@ as my own personal Google but I'm sure
someone knows this off the top of their head and can save me a lot of
reading.
I'm wondering about which specs mention how to handle URL parameters
(and POST parameters, for that matter) in terms of ordering. For
example, if I have a URL like:
https://example.com/context/resource?a=1&b=2&c=3&a=6
(Note that I have "a" in there twice)
If I call request.getParameterNames(), is there a predictable order in
which those parameters will be handed back? I'd love to hear that not
only are they returned in "URL order" (that is, the left-most parameter
is the first returned in that enumeration) in Tomcat, but either the
servlet spec, the CGI spec, or some other spec dictates that order
explicitly.
Yes, they will be in that order. (See ApplicationHttpRequest.parameters,
ParameterMap.delgatedMap and LinkedHashMap
The order isn't explicitly defined in any specification I am aware of.
However, the Servlet spec does state (3.1) that query string parameters
should be presented before parameters parsed form the request body.
There are several ways to implement that but it is likely that an
implementation will simply maintain insertion order for keys and values
(where there are multiple values for the same key) in a single
collection. At least, Tomcat does this.
Similarly, if I use request.getParameterMap and than iterate through the
keys or Map.Entry objects in it, does that behave predictably as well?
Same answer as above.
I have a situation where both URL parameters and POST parameters being
in URL-order (or document-order for POST parameters) would be highly
convenient, but I'd like to know if I can actually *rely* on that
behavior, or if I have to make arrangements to provide the ordering in a
separate parameter.
You can rely on this if you are using Tomcat. I don't see the underlying
design changing anytime soon. For other containers, YMMV.
I'd like to know which specs mention these things if they are indeed
specified in any of them.
The only thing I am aware of is the query string before request body
ordering in section 3.1. of the Servlet spec.
Thanks for all that. Experiments with Tomcat showed that the parameter
order was what I was expecting. I was wondering if that was simply an
implementation detail or if it was spec-mandated. It seems it's an
implementation detail, though it may be a popular one.
I wonder how difficult it would be to lobby the Servlet EG to codify
that behavior in the specification. I'm sure it would be advantageous to
all application developers if they could predict the order of
parameter-processing on the server side given the structure of their
URLs and HTTP POST form data.
My past attempts to get Servlet EG to do anything have been fruitless,
even for simple things[1]. Any idea if this kind of request would ever
actually be considered?
-chris
[1] https://github.com/eclipse-ee4j/servlet-api/issues/130
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