ORM (Object Relational Mapping) in Laravel: Manipulate databases elegantly

ORM (Object Relational Mapping) in Laravel: Manipulate the database elegantly

Introduction:
During the development process, interaction with the database is inevitable part. Using ORM (Object Relational Mapping) allows us to operate the database in an object-oriented manner without writing cumbersome SQL statements. The Laravel framework provides powerful and elegant ORM tools to facilitate developers to perform database operations. This article will introduce the use of ORM in Laravel, with code examples.

1. ORM in Laravel

ORM is a technology that maps objects to tables in a relational database and the relationships between tables. Using ORM, we can directly add, delete, modify, and query the database by operating objects without having to process the underlying SQL statements. The ORM in Laravel is implemented using Eloquent, which is a simple, elegant and powerful ORM tool.

Advantages:

1. Reduces the workload of writing SQL statements and improves development efficiency;
2. Operates the database in an object-oriented manner, making the code clearer and easier to read ;
3. Provides various convenient methods to simplify the database operation process;
4. Supports cross-platform migration of database to facilitate code transplantation and maintenance.

2. Basic use of Eloquent ORM

1. Define model and data table mapping relationship:
   First, we need to define a model to communicate with the specified data table mapping. In Laravel, a model is a class that inherits from Eloquent, and the mapping relationship between the data table and the model is determined through the naming convention of the model.

For example, if we have a users data table, then we can create a User model to correspond to it:

namespace App;
use IlluminateDatabaseEloquentModel; 
class User extends Model 
{ 
    // 指定数据表名
    protected $table = 'users'; 
}

2. Basic query operations:
   Laravel provides A rich set of methods for querying data. The following are several commonly used query methods:

3. Get all records:

   $users = User::all();

4. Get the first record:

   $user = User::first();

5. Search for records based on primary key:

   $user = User::find(1);

6. Search for records based on conditions:

   $users = User::where('age', '>', 18)->get();

7. Add, update and delete records:

8. Add record:

   $user = new User;
   $user->name = 'Tom';
   $user->age = 20;
   $user->save();

9. Update record:

   $user = User::find(1);
   $user->age = 25;
   $user->save();

10. Delete record:

    $user = User::find(1);
    $user->delete();

11. Association:
    Laravel's ORM supports association operations between database tables, such as one-to-one, one-to-many, many-to-many, etc.
    Taking one-to-many association as an example, we can define two models (User and Post), and define a one-to-many relationship with the Post model in the User model:

    namespace App;
    use IlluminateDatabaseEloquentModel;
    class User extends Model 
    {
     // 定义与Post模型的一对多关系
     public function posts()
     {
         return $this->hasMany('AppPost');
     }
    }

    Then, we can Get all the user's articles in the following way:

    $user = User::find(1);
    $posts = $user->posts;

Summary:
The ORM (Object Relational Mapping) in Laravel provides an elegant and powerful tool to facilitate developers to perform database operations. . By using ORM, we can simplify the process of database operations and develop in an object-oriented manner. This article introduces the basic use of ORM in Laravel and attaches code examples. I hope it will be helpful to readers. If you haven't used Laravel's ORM yet, you might as well try it. I believe you will fall in love with its simplicity and elegance.

Reference:

• Laravel Documentation. Eloquent ORM. https://laravel.com/docs/8.x/eloquent

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