◊(Local Yarn Code "Artifact [044c6c3e]")

Artifact 044c6c3e2ebeeaf968bf5013564eba752cef72553c914ce695f8c6debc778baf:


     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
    92
    93
    94
    95
    96
    97
    98
    99
   100
   101
   102
   103
   104
   105
   106
   107
   108
   109
   110
   111
   112
   113
   114
   115
   116
   117
   118
   119
   120
   121
   122
   123
   124
   125
   126
   127
   128
   129
   130
   131
   132
   133
   134
   135
   136
   137
   138
   139
   140
   141
   142
   143
   144
   145
   146
   147
   148
   149
   150
   151
   152
   153
   154
   155
   156
   157
   158
   159
   160
   161
   162
   163
   164
   165
   166
   167
   168
   169
   170
   171
   172
   173
   174
   175
   176
   177
   178
   179
   180
   181
   182
   183
   184
   185
   186
   187
   188
   189
   190
   191
   192
   193
   194
   195
   196
   197
   198
   199
   200
   201
   202
   203
   204
   205
   206
   207
   208
   209
   210
   211
   212
   213
   214
   215
   216
   217
   218
   219
   220
   221
   222
   223
   224
   225
   226
   227
   228
   229
   230
   231
   232
   233
   234
   235
   236
   237
   238
   239
   240
   241
   242
   243
   244
   245
   246
   247
   248
   249
   250
   251
   252
   253
   254
   255
   256
   257
   258
   259
   260
   261
   262
   263
   264
   265
   266
   267
   268
   269
   270
   271
   272
   273
   274
   275
   276
   277
#lang racket/base

;; Copyright (c) 2018 Joel Dueck.
;;
;; Licensed under the Apache License, Version 2.0 (the "License");
;; you may not use this file except in compliance with the License.
;; A copy of the License is included with this source code, in the
;; file "LICENSE.txt".
;; You may also obtain a copy of the License at
;;
;;       http://www.apache.org/licenses/LICENSE-2.0
;;
;; Unless required by applicable law or agreed to in writing, software
;; distributed under the License is distributed on an "AS IS" BASIS,
;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;; See the License for the specific language governing permissions and
;; limitations under the License.
;;
;; Author contact information:
;;   joel@jdueck.net
;;   https://joeldueck.com
;; -------------------------------------------------------------------------

;; Provides a very light set of utility functions for a SQLite database.
;; These functions are completely agnostic as to the database schema.
;; These functions are NOT SAFE for use with data provided by untrusted users!

(require db/sqlite3
         db/base
         racket/list
         racket/match
         racket/function
         racket/contract
         sugar/coerce)

(module+ test
  (require rackunit))

(provide (all-from-out db/base db/sqlite3))
(provide sqltools:dbc
         sqltools:log-queries?)

(provide
 (contract-out
  ;; Utility functions
  [log-query                 (string? . -> . void?)]
  [vector->hash              (vector? (listof symbolish?) . -> . hash?)]
  [backtick                  (stringish? . -> . string?)]
  [list->sql-fields          ((listof stringish?) . -> . string?)]
  [list->sql-values          ((listof stringish?) . -> . string?)]
  [list->sql-parameters      ((listof any/c) . -> . string?)]
  [bool->int                 (any/c . -> . exact-integer?)]
  [int->bool                 (exact-integer? . -> . boolean?)]

  ;; Simple SQL makers
  [make-table-schema         ((string? (listof stringish?))
                              (#:primary-key-cols (listof stringish?))
                              . ->* . string?)]
  [make-insert/replace-query (stringish? (listof stringish?) . -> . string?)]
  [make-insert-rows-query    (stringish? (listof stringish?) (listof (listof stringish?)) . -> . string?)]
  [make-select-query         (stringish? (listof stringish?) #:where stringish? . -> . string?)]

  ;; Database operations
  [init-db!                  ((pathish?) () #:rest (listof string?) . ->* . void?)]
  [query!                    ((string?) () #:rest (listof any/c) . ->* . void?)]
  [select-rows!              (case->
                              (stringish? (listof stringish?) any/c . -> . (or/c empty? hash?))
                              (string? (listof stringish?) . -> . (or/c empty? hash?)))]))

;; ~~~ Private use ~~~

(define uninitialized-connection "No DB connection!")
(define (weave xs ys)
  (for/fold [(woven null)
             #:result (reverse woven)]
            ([x (in-list xs)]
             [y (in-list ys)])
    (cons y (cons x woven))))

(define (sql-val v)
  (cond [(string? v) (string-append "\"" v "\"")]
        [else (format "~a" v)]))

;; ~~~ Provided parameters ~~~

(define sqltools:dbc (make-parameter uninitialized-connection))
(define sqltools:log-queries? (make-parameter #f))

;; ~~~ Provided utility functions ~~~

(define (backtick str) (format "`~a`" str))
(define (list->sql-fields fields) (apply string-append (add-between (map backtick fields) ", ")))
(define (list->sql-values vals)
  (string-append "(" (apply string-append (add-between (map sql-val vals) ", ")) ")"))
(define (list->sql-parameters fields)
  (apply string-append (add-between (map (λ(x) (format "?~a" (add1 x))) (range (length fields))) ", ")))

;; For storing/reading boolean values (SQLite uses integers)
(define (bool->int b?)
  (cond [b? 1] [else 0]))

(define (int->bool i)
  (not (= i 0)))

;; TESTING: utility functions…
(module+ test
  (check-equal? (backtick "field") "`field`")
  (check-equal? (list->sql-fields '("f1" "f2" "f3")) "`f1`, `f2`, `f3`")
  (check-equal? (list->sql-fields '(f1 f2 f3)) "`f1`, `f2`, `f3`") ; Can use symbols too
  (check-equal? (list->sql-parameters '("name" "rank" "serial")) "?1, ?2, ?3")
  (check-equal? (list->sql-parameters '(name rank serial)) "?1, ?2, ?3")
  (check-equal? (list->sql-values '(100 "hello" 3)) "(100, \"hello\", 3)")
  (check-equal? (weave '(x y z) '(1 2 3)) '(x 1 y 2 z 3))
  
  (check-equal? (bool->int #f) 0)
  (check-equal? (bool->int #t) 1)
  (check-equal? (bool->int "xblargh") 1)
  (check-equal? (int->bool 0) #f)
  (check-equal? (int->bool 1) #t)
  (check-equal? (int->bool -1) #t)
  (check-equal? (int->bool 37) #t)
  (check-exn exn:fail? (lambda () (int->bool "x"))))

;; ~~~ Public functions ~~~

;; Prints to stdout if logging is on
(define (log-query q) (unless (not (sqltools:log-queries?)) (println q)))

;; Using a list of field names, convert a vector into a hash that uses the
;; field names (in symbol form) for keys.
;; Racket’s db functions all return vectors; hashes are much easier to use.
;; If fields and v are not equal in length, the unpairable elements are omitted
;; from the hash!
(define (vector->hash v fields)
  (cond [(zero? (vector-length v)) null]
        [else (let ([keys (map ->symbol fields)]
                    [vals (vector->list v)])
                (apply hash (weave keys vals)))]))

;; TESTING: vector->hash...
(module+ test
  (let ([test-row '#("Joe" "PFC" 123)]
        [test-cols-SYMBOL '(name rank serial)]
        [test-cols-STRING '("name" "rank" "serial")]
        [desired-result '#hash((serial . 123) (rank . "PFC") (name . "Joe"))])
    (check-equal? (vector->hash test-row test-cols-SYMBOL) desired-result)
    (check-equal? (vector->hash test-row test-cols-STRING) desired-result))

  ;; Behavior when v and fields are unequal in length:
  (check-equal? (vector->hash '#("foo" "bar") '(a b c))
                '#hash((a . "foo") (b . "bar")))
  (check-equal? (vector->hash '#("foo" "bar" "baz") '(a b))
                '#hash((a . "foo") (b . "bar"))))

;; Create a simple table schema from a list of fields, optionally specifying
;; primary key
(define (make-table-schema tablename fields #:primary-key-cols [primary-cols '()])
  (define primary-key
    (format "PRIMARY KEY (~a)"
            (list->sql-fields (if (empty? primary-cols) (list (first fields)) primary-cols))))
  (format "CREATE TABLE IF NOT EXISTS `~a` (~a, ~a);"
          tablename
          (list->sql-fields fields)
          primary-key))

;; Create a query that inserts a row if it doesn’t exist (based on the first
;; column only), or updates it if it does. The returned query is parameterized,
;; and must be used with a list of values equal in length to the number of
;; fields given.
(define (make-insert/replace-query tablename fields)
  (format "INSERT OR REPLACE INTO `~a` (`rowid`, ~a) VALUES ((SELECT `rowid` FROM `~a` WHERE `~a`= ?1), ~a)"
          tablename
          (list->sql-fields fields)
          tablename
          (first fields)
          (list->sql-parameters fields)))

;; Create a query that inserts multiple rows.
(define (make-insert-rows-query tablename fields rows)
  (define row-values
    (apply string-append (add-between (map list->sql-values rows) ", ")))
  (format "INSERT INTO `~a` (~a) VALUES ~a;" tablename (list->sql-fields fields) row-values))

;; Simple row selection
(define (make-select-query table fields #:where where-clause)
  (format "SELECT ~a FROM `~a` WHERE ~a"
          (list->sql-fields fields)
          table
          where-clause))

;; TESTING: SQL query makers...
(module+ test
  (check-equal? (make-table-schema 'posts '(title date))
                "CREATE TABLE IF NOT EXISTS `posts` (`title`, `date`, PRIMARY KEY (`title`));")
  (check-equal? (make-table-schema "posts" '("title" "date"))
                "CREATE TABLE IF NOT EXISTS `posts` (`title`, `date`, PRIMARY KEY (`title`));")
  (check-equal? (make-table-schema 'posts '(title date) #:primary-key-cols '(author date))
                "CREATE TABLE IF NOT EXISTS `posts` (`title`, `date`, PRIMARY KEY (`author`, `date`));")

  (check-equal? (make-insert/replace-query 'posts '(author title))
                (string-append "INSERT OR REPLACE INTO `posts` (`rowid`, `author`, `title`) "
                               "VALUES ((SELECT `rowid` FROM `posts` WHERE `author`= ?1), ?1, ?2)"))

  (check-equal? (make-insert-rows-query 'series '(id name num) '((1 "Journal" 11) (2 "Ideas" 4)))
                (string-append "INSERT INTO `series` (`id`, `name`, `num`) "
                               "VALUES (1, \"Journal\", 11), (2, \"Ideas\", 4);"))
  
  (check-equal? (make-select-query 'posts '(author title) #:where 1)
                "SELECT `author`, `title` FROM `posts` WHERE 1"))

(define (good-connection?)
  (and (connection? (sqltools:dbc)) (connected? (sqltools:dbc))))

;; Initialize the database connection, creating the database if it does not yet exist
;; and running any provided queries (e.g., "CREATE TABLE IF NOT EXISTS...")
(define (init-db! filename . qs)
  (cond [(good-connection?) (disconnect (sqltools:dbc))])
  (sqltools:dbc (sqlite3-connect #:database filename #:mode 'create))
  (unless (empty? qs)
    (for ([q (in-list qs)])
         (query! q))))

;; Run a query with logging (if enabled) and return the result
(define (query! q . parameters)
  (unless (good-connection?) (error "(query!) DB not connected"))
  (log-query q)
  (cond [(empty? parameters) (query-exec (sqltools:dbc) q)]
        [else (apply query-exec (sqltools:dbc) q parameters)]))

;; Run a SELECT query, return a hash with field names as keys
(define select-rows!
  (case-lambda
    ;; Use arbitrary query
    [(query fieldnames)
     (unless (good-connection?) (error "(select-rows!) DB not connected"))
     (log-query query)
     (define result (query-rows (sqltools:dbc) query))
     (map (curryr vector->hash fieldnames) result)]
    
    ;; Use a simple SELECT FROM WHERE template
    [(table fields where-clause)
     (unless (good-connection?) (error "(select-rows!) DB not connected"))
     (define query (make-select-query table fields #:where where-clause))
     (log-query query)
     (define result (query-rows (sqltools:dbc) query))
     (map (curryr vector->hash fields) result)]))

;; TESTING: database connection state and queries
(module+ test
  (define TESTDB "SQLITE-TOOLS-TEST.sqlite")

  ;; Check that things start out uninitialized and that queries don’t work
  (check-equal? (sqltools:dbc) uninitialized-connection)
  (check-false (file-exists? TESTDB))
  (check-exn exn:fail? (lambda () (query! "SELECT 1")))
  (check-exn exn:fail? (lambda () (select-rows! 'posts '(title) 1)))
  
  ;; Initialize db connection, create file with no schema
  (test-begin
   (check-equal? (init-db! TESTDB) (void))
   (check-true (file-exists? TESTDB))
   (delete-file TESTDB))

  ;; Initialize new db/connection, create file with schema, check that
  ;; simple queries return expected results
  (test-begin
   (check-equal? (init-db! TESTDB (make-table-schema 'posts '(title date))) (void))
   (check-true (file-exists? TESTDB))
   (check-equal? (select-rows! (make-select-query 'posts '(title date) #:where 1) '(title date)) null)
   (check-equal? (query! (make-insert/replace-query 'posts '(title date)) "Hello" "2018-08-10") (void))
   (check-equal? (select-rows! 'posts '(title date) "`date`='2018-08-10'")
                 '(#hash((title . "Hello") (date . "2018-08-10")))))

  ;; Clean up
  (disconnect (sqltools:dbc))
  (sqltools:dbc uninitialized-connection)
  (delete-file TESTDB))