blob: 51b332da4a93bae512ab0949cc0adb9988fe4343 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
#lang racket
(provide
;; Model struct
crop
crop?
crop-id crop-name
(contract-out
;; SQL CRUD
[create-crop! (-> string? crop?)]
[get-crops (-> (listof crop?))]
[get-crop (->* ()
(#:id (or/c #f exact-nonnegative-integer?)
#:name (or/c #f string?))
(or/c crop? #f))]
[update-crop! (->* (exact-nonnegative-integer?)
(#:name (or/c #f string?))
(or/c crop? #f))]
[delete-crop! (-> exact-nonnegative-integer? void?)]))
(require racket/contract
db
sql
"../db/conn.rkt")
(struct crop (id name) #:transparent)
;; CREATE
(define (create-crop! name)
(or (get-crop #:name name)
(begin
(query-exec (current-conn)
(insert #:into crops
#:set [canonical_name ,name]))
(get-crop #:name name))))
;; READ
(define (get-crops)
(for/list ([(id* name*)
(in-query (current-conn)
(select id canonical_name
#:from crops
#:order-by id #:asc))])
(crop id* name*)))
(define (get-crop #:id [id #f]
#:name [name #f])
(define where
(cond
[(and id name)
(scalar-expr-qq (and (= id ,id)
(= canonical_name ,name)))]
[id
(scalar-expr-qq (= id ,id))]
[name
(scalar-expr-qq (= canonical_name ,name))]))
(define query (select id canonical_name
#:from crops
#:where (ScalarExpr:AST ,where)
#:order-by id #:asc
#:limit 1))
(match (query-maybe-row (current-conn) query)
[(vector id* name*)
(crop id* name*)]
[#f #f]))
;; UPDATE
(define (update-crop! id
#:name [name #f])
(cond
[name
(query-exec (current-conn)
(update crops
#:set [canonical_name ,name]
#:where (= id ,id)))]
[else (void)])
(or (get-crop #:id id)
(error 'update-crop! "No crop with id ~a" id)))
;; DELETE
(define (delete-crop! id)
(query-exec (current-conn)
(delete #:from crops #:where (= id ,id))))
|
