Racket : How do i print the mysql result in a HTML page - html

Question

I am trying print the values from the DB on the HTML page generated in APPLICATION.rkt
but this is what i see when i execute the code below
&createstring;&db-conn;SELECT * from students
Here is what I am trying to execute:
#lang racket
(require db)
(require web-server/servlet)
(provide/contract (start (request? . -> . response?)))
(define db-conn
(virtual-connection
(lambda () (mysql-connect #:server "localhost"
#:port 8889
#:database "SOB"
#:user "root"
#:password "root"))))
(define (start request)
(define (createstring id name sid)
(string-append "id is " id "and name is " name "and sid is " sid))
(response/xexpr
'(html
(head (title "SOB"))
(body
,#(map (h1) (map createstring (in-query db-conn "SELECT * from students"))))
)))
(require web-server/servlet-env)
(serve/servlet start
#:launch-browser? #f
#:quit? #f
#:listen-ip #f
#:port 8080
#:extra-files-paths
(list (build-path "/Users/lalith/Documents/LALITH FILES/MDX/SOB/" "htmlfiles"))
#:servlet-path
"/servlets/APPLICATION.rkt")
Any suggestions as to what I'm doing wrnog?

Answer 1

There are a couple problems.
First, use quasiquote (or "backquote") instead of quote; otherwise you can't escape from it with ,# (ie, unquote-splicing). In other words, change
'(html ___)
to
`(html ___)
Then, inside the ,# escape, your maps are wrong, and map doesn't work with in-query anyway. You probably want something like this instead:
,#(for/list ([(id name sid)
(in-query db-conn "SELECT id, name, sid from students")])
`(h1 ,(createstring id name sid)))
Or something like that. (The code above would make a level-1 header for each row in the table, if that's what you want.)
Edited in response to comment: It looks like id is a numeric column in the database. If you have a recent version of Racket, I recommend using ~a, which is like string-append but automatically converts non-string values to strings first. Change the definition of createstring to this:
(define (createstring id name sid)
(~a "id is " id "and name is " name "and sid is " sid))
In older versions of Racket (before ~a), use format instead (see the docs for how).