This appendix shows a version of the page script from Appendix B after being converted to use Gateway classes. Note how very little of it has changed. Even though the SQL statements have been removed, the domain business logic remains embedded in the page script.
The Gateway classes are provided below the page script, and show a conversion to PDO-style bound parameters. Also note that there have been minor modifications to the if() conditions in the page script: whereas previously they checked to see if a query succeeded, they now check for a return value from the Gateway.
page_script.php
<?php
2 // ... $user_id value created earlier
3
4 $db = new Database($db_host, $db_user, $db_pass);
5 $articles_gateway = new ArticlesGateway($db);
6 $users_gateway = new UsersGateway($db);
7
8 $article_types = array(1, 2, 3, 4, 5);
9 $failure = array();
10 $now = time();
11
12 // sanitize and escape the user input
13 $input = $_POST;
14 $input['body'] = strip_tags($input['body']);
15 $input['notes'] = strip_tags($input['notes']);
16
17 if (isset($input['ready']) && $input['ready'] == 'on') {
18 $input['ready'] = 1;
19 } else {
20 $input['ready'] = 0;
21 }
22
23 // nothing less than 0.01 credits per rating
24 $input['credits_per_rating'] = round(
25 $input['credits_per_rating'],
26 2
27 );
28
29 $credits = round(
30 $input['credits_per_rating'] * $input['max_ratings'],
31 2
32 );
33
34 // updating an existing article?
35 if ($input['id']) {
36
37 $row = $articles_gateway->selectOneByIdAndUserId($input['id'], $user_id);
38
39 if ($row) {
40
41 // don't charge unless the article is ready
42 $decrement = false;
43
44 // is the article marked as ready?
45 if ($input['ready'] == 1) {
46
47 // did they offer at least the minimum?
48 if (
49 $credits > 0
50 && $input['credits_per_rating'] >= 0.01
51 && is_numeric($credits)
52 ) {
53
54 // was the article previously ready for review?
55 // (note 'row' not 'input')
56 if ($row['ready'] == 1) {
57
58 // only subtract (or add back) the difference to their
59 // account, since they already paid something
60 if (
61 is_numeric($row['credits_per_rating'])
62 && is_numeric($row['max_ratings'])
63 ) {
64 // user owes $credits, minus whatever they paid already
65 $amount = $row['credits_per_rating']
66 * $row['max_ratings']
67 $credits = $credits - $amount;
68 }
69
70 $decrement = true;
71
72 } else {
73 // article not ready previously, so they hadn't
74 // had credits deducted. if this is less than their
75 // in their account now, they may proceed.
76 $residual = $user->get('credits') - $credits;
77 $decrement = true;
78 }
79
80 } else {
81 $residual = -1;
82 $failure[] = "Credit offering invalid.";
83 $decrement = false;
84 }
85
86 } else {
87
88 // arbitrary positive value; they can proceed
89 $residual = 1;
90
91 // if it was previously ready but is no longer, refund them
92 if (
93 is_numeric($row['credits_per_rating'])
94 && is_numeric($row['max_ratings'])
95 && ($row['ready'] == 1)
96 ) {
97 // subtract a negative value
98 $amount = $row['credits_per_rating']
99 * $row['max_ratings']
100 $credits = -($amount);
101 $decrement = true;
102 }
103 }
104
105 if ($residual >= 0) {
106
107 $input['ip'] = $_SERVER['REMOTE_ADDR'];
108 $input['last_edited'] = $now;
109
110 if (! in_array(
111 $input['article_type'],
112 $article_types
113 )) {
114 $input['article_type'] = 1;
115 }
116
117 $result = $articles_gateway->updateByIdAndUserId(
118 $input['id'],
119 $user_id,
120 $input
121 );
122
123 if ($result) {
124 $article_id = $input['id'];
125
126 if ($decrement) {
127 $users_gateway->decrementCredits($user_id, $credits);
128 }
129 } else {
130 $failure[] = "Could not update article.";
131 }
132 } else {
133 $failure[] = "You do not have enough credits for ratings.";
134 }
135 }
136
137 } else {
138
139 // creating a new article. do not decrement until specified.
140 $decrement = false;
141
142 // if the article is ready, we need to subtract credits.
143 if ($input['ready'] == 1) {
144
145 // if this is greater than or equal to 0, they may proceed.
146 if (
147 $credits > 0
148 && $input['credits_per_rating']>=0.01
149 && is_numeric($credits)
150 ) {
151 // minimum offering is 0.01
152 $residual = $user->get('credits') - $credits;
153 $decrement = true;
154 } else {
155 $residual = -1;
156 $failure[] = "Credit offering invalid.";
157 }
158
159 } else {
160 // arbitrary positive value if they are not done with their article.
161 // no deduction made yet.
162 $residual = 1;
163 }
164
165 // can user afford ratings on the new article?
166 if ($residual >= 0) {
167
168 // yes, insert the article
169 $input['last_edited'] = $now;
170 $input['ip'] = $_SERVER['REMOTE_ADDR'];
171 $article_id = $articles_gateway->insert($input);
172
173 if ($article_id) {
174 if ($decrement) {
175 // Charge them
176 $users_gateway->decrementCredits($user_id, $credits);
177 }
178 } else {
179 $failure[] = "Could not update credits.";
180 }
181
182 $result = $articles_gateway->updateByIdAndUserId(
183 $article_id,
184 $user_id,
185 $input
186 );
187
188 if (! $result) {
189 $failure[] = "Could not update article.";
190 }
191
192 } else {
193
194 // cannot afford ratings on new article
195 $failure[] = "You do not have enough credits for ratings.";
196 }
197 }
198 ?>
classes/Domain/Articles/ArticlesGateway.php
1 <?php
2 namespace Domain\Articles;
3
4 class ArticlesGateway
5 {
6 protected $db;
7
8 public function __construct(Database $db)
9 {
10 $this->db = $db;
11 }
12
13 public function selectOneByIdAndUserId($id, $user_id)
14 {
15 $stm = "SELECT *
16 FROM articles
17 WHERE user_id = :user_id
18 AND id = :id
19 LIMIT 1";
20
21 return $this->db->query($stm, array(
22 'id' => $id,
23 'user_id' => $user_id,
24 ))
25 }
26
27 public function updateByIdAndUserId($id, $user_id, $input)
28 {
29 if (strlen($input['notes']) > 0) {
30 $notes = "notes = :notes";
31 } else {
32 $notes = "notes = NULL";
33 }
34
35 if (strlen($input['title']) > 0) {
36 $title = "title = :title";
37 } else {
38 $title = "title = NULL";
39 }
40
41 $input['id'] = $id;
42 $input['user_id'] = $user_id;
43
44 $stm = "UPDATE articles
45 SET
46 body = :body,
47 $notes,
48 $title,
49 article_type = :article_type,
50 ready = :ready,
51 last_edited = :last_edited,
52 ip = :ip,
53 credits_per_rating = :credits_per_rating,
54 max_ratings = :max_ratings
55 WHERE user_id = :user_id
56 AND id = :id";
57
58 return $this->query($stm, $input);
59 }
60
61 public function insert($input)
62 {
63 $stm = "INSERT INTO articles (
64 user_id,
65 ip,
66 last_edited,
67 article_type
68 ) VALUES (
69 :user_id,
70 :ip,
71 :last_edited,
72 :article_type
73 )";
74 $this->db->query($stm, $input);
75 return $this->db->lastInsertId();
76 }
77 }
78 ?>
classes/Domain/Users/UsersGateway.php
1 <?php
2 namespace Domain\Users;
3
4 class UsersGateway
5 {
6 protected $db;
7
8 public function __construct(Database $db)
9 {
10 $this->db = $db;
11 }
12
13 public function decrementCredits($user_id, $credits)
14 {
15 $stm = "UPDATE users
16 SET credits = credits - :credits
17 WHERE user_id = :user_id";
18 $this->db->query($stm, array(
19 'user_id' => $user_id,
20 'credits' => $credits,
21 ));
22 }
23 }
24 ?>