README

是 atk4/data 的扩展，以便轻松管理多对多（MToM）关系。目的是在实际的多对多操作中编写尽可能少的代码。

项目内容

该项目包含两个文件

• JunctionModel：一个连接类的基模型（如StudentToLesson）。可以通过几行代码编写工作后代码。在这里实现了添加（例如，StudentToLesson::addMToMRelation($student, $lesson);）、删除（例如，StudentToLesson::removeMToMRelation($student, $lesson);）和检查（例如，StudentToLesson::hasMToMRelation($student, $lesson);）的静态方法。
• MToMTrait：一个特质，用于添加到要链接的模型中（如Student和Lesson）。使用此特质，可以在Model::init()中用一行代码定义MToM关系：$this->addMToMReferenceAndDeleteHook();。

如何使用

安装

使用此存储库的最简单方法是将其添加到composer.json的require部分

{
  "require": {
    "philippgrashoff/mtomforatk": "4.0.*"
  }
}

示例代码

例如，让我们使用Students和Lessons。一个学生可以有多个课程，一个课程可以有多个学生。为了映射这种多对多关系，创建了3个类。此示例的演示模型可以在tests\Testmodels中找到

• Student：一个使用MToMTrait的正常模型。
• Lesson：一个使用MToMTrait的正常模型。
• StudentToLesson：携带每个学生和课程之间的MToM关系的student_id和lesson_id的连接模型。

设置这些类后，可以使用此项目轻松执行MToM操作

<?php declare(strict_types=1);

use Atk4\Data\Persistence\Sql;
use PhilippR\Atk4\MToM\Tests\Testmodels\Lesson;
use PhilippR\Atk4\MToM\Tests\Testmodels\Student;
use PhilippR\Atk4\MToM\Tests\Testmodels\StudentToLesson;

$persistence = new Sql('sqlite::memory:');

$studentHarry = (new Student($persistence))->createEntity();
$studentHarry->set('name', 'Harry');
$studentHarry->save();
$lessonGeography = (new Lesson($persistence))->createEntity();
$lessonGeography->set('name', 'Geography');
$lessonGeography->save();

//now, lets easily add Harry to the Geography lesson:
StudentToLesson::addMToMRelation($studentHarry, $lessonGeography);
//the above line created a StudentToLesson record with student_id = studentHarry's ID and lesson_id = lessonGeography's ID

//let's add Harry to another lesson
$lessonBiology = (new Lesson($persistence))->createEntity();
$lessonBiology->set('name', 'Biology');
$lessonBiology->save();
//adding/removing can either be done by passing the other model or only it's ID. In this case, we just pass the ID - that's what you typically get from UI
StudentToLesson::addMToMRelation($studentHarry, $lessonBiology->getId());
//this created another StudentToLesson record with student_id = studentHarry's ID and lesson_id = lessonBiology's ID

//Let's easily check if an MToM relation exists
StudentToLesson::hasMToMRelation($studentHarry, $lessonGeography); //true;

//harry is tired of Geography, lets remove him from this lesson:
StudentToLesson::removeMToMRelation($studentHarry, $lessonGeography);
//this removed the StudentToLesson Record linking Harry to Geography.
StudentToLesson::hasMToMRelation($studentHarry, $lessonGeography);  //false

//Linda attends both courses. Let's add Linda to both courses. But this time we do it the other way around and pass the lesson model as first argument:
$studentLinda = (new Student($persistence))->createEntity();
$studentLinda->set('name', 'Linda');
$studentLinda->save();
StudentToLesson::addMToMRelation($lessonGeography, $studentLinda);
StudentToLesson::addMToMRelation($lessonBiology, $studentLinda);

此README中的示例代码可以在docs目录中找到。

版本控制

此存储库的版本号与atk4\data版本相对应。因此，4.0.x与atk4\data 4.0.x兼容，依此类推。