Hi Everyone,
I'm having trouble getting the value associated with a key in a
hash-table and I'm totally confused as to what I'm doing wrong. The
code I'm using is shown below:
(use-modules (curl))
(use-modules (json))
;; use curl to hit the site's api to get results of query as json:
(define handle (curl-easy-init))
(curl-easy-setopt handle 'url
"http://api.data.gov:80/regulations/v3/documents.json?api_key=mySecKey&countsOnly=0&encoded=1&dktid=EPA-HQ-OAR-2013-0602&dkt=R&cp=C&rpp=25&po=0";)
(define s (curl-easy-perform handle))
;; parse the json in the string into guile scheme:
(define queryResults (json-string->scm s))
;; use this to see the keys and values in the resulting hash
table:
(define print-hash (lambda (my-hash)
(hash-for-each (lambda (key value)
(format #t "~a => ~a~%" key value))
my-hash)))
;; now let's take a look at the keys and values:
(print-hash queryResults)
;; now let's get the value associated with the documents key:
(hashq-get-handle queryResults 'documents)
It relies on [guile-curl][1] and [guile-json][2] to talk to the
webserver and to parse the response. Things seem pretty
straight-forward until I run. I can see the response from the server
in json (very long and not posted here) and from within Emacs (using
geiser to poke around) I can see:
scheme@(guile-user)> (hash-table? queryResults)
$25 = #t
so I know that queryResults is indeed a hash-table. When I take a
look at the keys and associated values using print-hash I see that:
scheme@(guile-user)> (print-hash queryResults)
totalNumRecords => 23318
documents => (#<hash-table 2ad7c60 17/31> #<hash-table 2afdbc0
17/31> #<hash-table 2b0ab60 17/31> #<hash-table 2b0eb00 17/31>
#<hash-table 2b10aa0 17/31> #<hash-table 2b13a40 17/31> #<hash-table
2b189e0 17/31> #<hash-table 2b1b980 17/31> #<hash-table 2b1e920 17/31>
#<hash-table 2b228c0 17/31> #<hash-table 2b25860 17/31> #<hash-table
2b29800 17/31> #<hash-table 2b2d7a0 17/31> #<hash-table 2b30740 17/31>
#<hash-table 2b336e0 17/31> #<hash-table 2b38680 17/31> #<hash-table
2b3b620 17/31> #<hash-table 2b3f5c0 17/31> #<hash-table 2b44560 17/31>
#<hash-table 2b48500 17/31> #<hash-table 2b4c4a0 17/31> #<hash-table
2b50440 17/31> #<hash-table 2b533e0 17/31> #<hash-table 2b57380 17/31>
#<hash-table 2b5c320 17/31>)
so that's good and it's what I expected. But when I try to use
hashq-get-handle to get a look at the value for totalNumRecords or
documents I get:
scheme@(guile-user)> (hashq-get-handle queryResults 'totalNumRecords)
$24 = #f
scheme@(guile-user)> (hashq-get-handle queryResults 'documents)
$24 = #f
which seems to indicate the key doesn't exist in the hash-table
queryResults. I've tried all night with quotes, w/o quotes, futzing
with the SRFI-69 hash-table implementations (during which I discovered
the difference between native guile hash-tables and the SRFI-69
hash-tables), and went through the [hash table examples][3] in the
guile reference manual (they all worked just fine). I'm out of ideas.
If someone could help me understand why my calls to hashq-get-handle
aren't working out as expected I'd be most grateful.
BTW, this question is also posted at:
http://stackoverflow.com/questions/27348357/trouble-using-hashq-get-handle-in-guile
Thanks for the help in advance.
[1]: http://www.lonelycactus.com/guile-curl.html
[2]: https://github.com/aconchillo/guile-json
[3]:
http://www.gnu.org/software/guile/manual/html_node/Hash-Table-Examples.html#Hash-Table-Examples
-j
--
-------------------------------------------------------------
Jamil Egdemir
uncleja...@gmail.com
http://www.power-quant.com
(631) 338-3170 (cell)
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