Laravel’s Seeders是Laravel项目中的数据库/seeders目录中生活的特殊类,允许您在数据库中编程地插入默认或样本记录的集合。
在代码编辑器中,打开以下文件:
1database/seeders/LinkSeeder.php
它将包含以下代码:
1[label database/seeders/LinkSeeder.php]
2<?php
3
4namespace Database\Seeders;
5
6use App\Models\Link;
7use Illuminate\Database\Seeder;
8use Illuminate\Support\Facades\DB;
9use Symfony\Component\Yaml\Yaml;
10
11class LinkSeeder extends Seeder
12{
13 /**
14 * Run the database seeds.
15 *
16 * @return void
17 */
18 public function run()
19 {
20 //only import seeds if DB is empty.
21 if (!Link::count()) {
22 $this->importLinks();
23 }
24 }
25
26 /**
27 * Imports Links from the default links.yml file at the root of the app.
28 * Change that file to import a set of personal basic links you want to show
29 * as soon as the application is deployed.
30 */
31 public function importLinks()
32 {
33 $links_import_path = __DIR__ . '/../../links.yml';
34
35 $yaml = new Yaml();
36 if (is_file($links_import_path)) {
37 $links = $yaml->parsefile($links_import_path);
38
39 foreach ($links as $link) {
40 DB::table('links')->insert([
41 'url' => $link['url'],
42 'description' => $link['description']
43 ]);
44 }
45 }
46 }
47}
请注意,此代码不使用链接模型,而是使用 查询构建器在数据库中插入新链接,这是Laravel中与数据库记录的不同工作方式,不依赖于Eloquent模型。
要改进此代码,您将更改前方循环以使用 Eloquent 模型,而不是直接通过查询构建程序查询数据库,您还需要在循环开始之前创建一个默认的链接列表(以下代码中称为$default_list),以便您可以在创建的每一个新链接中引用此列表。
用以下代码更换您的播种类中的当前内容:
1[label database/seeders/LinkSeeder.php]
2<?php
3
4namespace Database\Seeders;
5
6use App\Models\Link;
7use App\Models\LinkList;
8use Illuminate\Database\Seeder;
9use Illuminate\Support\Facades\DB;
10use Symfony\Component\Yaml\Yaml;
11
12class LinkSeeder extends Seeder
13{
14 /**
15 * Run the database seeds.
16 *
17 * @return void
18 */
19 public function run()
20 {
21 //only import seeds if DB is empty.
22 if (!Link::count()) {
23 $this->importLinks();
24 }
25 }
26
27 /**
28 * Imports Links from the default links.yml file at the root of the app.
29 * Change that file to import a set of personal basic links you want to show
30 * as soon as the application is deployed.
31 */
32 public function importLinks()
33 {
34 $links_import_path = __DIR__ . '/../../links.yml';
35
36 $yaml = new Yaml();
37 if (is_file($links_import_path)) {
38 $links = $yaml->parsefile($links_import_path);
39
40 $default_list = new LinkList();
41 $default_list->title = "Default";
42 $default_list->description = "Default List";
43 $default_list->slug = "default";
44 $default_list->save();
45
46 foreach ($links as $link) {
47 $seed_link = new Link();
48 $seed_link->url = $link['url'];
49 $seed_link->description = $link['description'];
50
51 $default_list->links()->save($seed_link);
52 }
53 }
54 }
55}
更新的代码使用面向对象的方法来设置由Eloquent转换为表列的LinkList和List模型的属性。为循环的最后一行使用$default_list对 links表的引用,可通过links()方法访问,以便在该列表中保存新的链接。
完成后保存文件 Laravel 播种器只在数据库空时运行,以免与以其他方式插入数据库的实际数据发生冲突。
运行以下命令来删除开发数据库:
1docker-compose exec app php artisan db:wipe
1[secondary_label Output]
2Dropped all tables successfully.
现在,要重新创建表 **并运行更新的播种器,您可以使用以下命令手工迁移 - 种子:
1docker-compose exec app php artisan migrate --seed
您应该收到类似于以下的输出:
1[secondary_label Output]
2Migration table created successfully.
3Migrating: 2014_10_12_000000_create_users_table
4Migrated: 2014_10_12_000000_create_users_table (124.20ms)
5Migrating: 2014_10_12_100000_create_password_resets_table
6Migrated: 2014_10_12_100000_create_password_resets_table (121.75ms)
7Migrating: 2019_08_19_000000_create_failed_jobs_table
8Migrated: 2019_08_19_000000_create_failed_jobs_table (112.43ms)
9Migrating: 2020_11_18_165241_create_links_table
10Migrated: 2020_11_18_165241_create_links_table (61.04ms)
11Migrating: 2021_07_09_122027_create_link_lists_table
12Migrated: 2021_07_09_122027_create_link_lists_table (112.18ms)
13Seeding: Database\Seeders\LinkSeeder
14Seeded: Database\Seeders\LinkSeeder (84.57ms)
15Database seeding completed successfully.
在本系列的下一章中,您将详细了解如何使用 Eloquent 查询数据库记录。