Detailed explanation of the implementation principle of ORM in laravel

Laravel is a widely used and acclaimed PHP framework. It provides many useful features, from database access to routing and controllers. Among them, ORM (Object-Relational Mapping) is an important component in Laravel. It provides a convenient way to operate the database and makes your code clearer and easier to understand. In this article, we will take an in-depth look at the implementation principles of Laravel ORM.

What is ORM?

First let’s briefly introduce ORM. ORM is a technology that establishes mapping between object-oriented programming (OOP) and relational databases. In the ORM, each table corresponds to a class and each row corresponds to an object. In this way, database operations can be simplified through objects, making the code clearer and easier to understand. The benefit of ORM is that it allows you to access the database in a more natural way instead of using SQL statements. Therefore, ORM is very important in Laravel, it allows us to let PHP interact with the database and write code faster and more reliably.

Laravel ORM implementation principle

Laravel's ORM implementation is based on the Active Record design pattern. In Active Record, a class corresponds to a table, and an instance of this class corresponds to a row. Laravel uses Eloquent ORM as the default ORM, which is a powerful and easy-to-use ORM. Eloquent allows you to simplify the process of working with databases by manipulating objects.

Below, we will have an in-depth understanding of the implementation principle of Laravel ORM:

Connect to the database

Before using the ORM, we need to connect to the database first. In Laravel, the PDO extension library is used to connect to relational databases. Before using Laravel ORM, we must first define which database to use. Laravel will connect to the database based on this setting.

Define model

In Laravel, each database table corresponds to an Eloquent model. This model is an ordinary PHP class that needs to inherit from the Illuminate\Database\Eloquent\Model class. In the Eloquent model, we can define the data table name, primary key and fillable fields corresponding to a model. These settings will automatically handle the operations of the data table and corresponding data records through Eloquent.

For example, to define a User model in Laravel, we can write:

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class User extends Model
{
    protected $table = 'users';

    protected $primaryKey = 'id';

    protected $fillable = ['name', 'email', 'password'];
}

In the above code, the $table attribute specifies the corresponding data table name "users", $primaryKey The attribute specifies the primary key field name "id" in the corresponding data table, and the $fillable attribute specifies the field that can be automatically updated through Eloquent.

Query method

The most basic function of ORM is to query the database. In Laravel, Eloquent provides many query methods, allowing us to easily query, filter and sort data.

For example, we can query all users in the User table in the following way:

$users = App\Models\User::all();

This query method will query the database table "users" through the model class User and return a list containing all The user's Eloquent collection object.

We can also use the query builder to build more complex query statements. For example:

$users = App\Models\User::where('name', 'John')->orderBy('id', 'desc')->get();

This query statement will query all users named "John", sort them in descending order according to the ID field, and return an Eloquent collection object.

Insert data

In Laravel, it is very convenient to use ORM to insert data. We only need to create a new Eloquent model instance, set the values ​​of the corresponding fields, and then save it to the database through the save() method.

For example, we can insert a new piece of data into the User table in the following way:

$user = new App\Models\User;

$user->name = 'John Doe';
$user->email = 'john@example.com';
$user->password = bcrypt('secret');

$user->save();

This insertion operation will create a new User instance and set its "name", " email", "password" properties and then save it to the database.

Update data

In Laravel, we can also easily update data through Eloquent. We only need to find the data record to be updated, then set the value of the corresponding field, and finally call the save() method to update it to the database.

For example, we can find a record through the id field, and then update its "name" field to "Jane":

$user = App\Models\User::find(1);

$user->name = 'Jane';

$user->save();

This update operation will find the user record with the primary key 1 , update its "name" field to "Jane", and then update it to the database.

Delete data

Finally, we can also easily delete data records in Laravel. We only need to find the data record to be deleted and then call the delete() method.

For example, we can find a record through the id field, and then delete it:

$user = App\Models\User::find(1);

$user->delete();

This deletion operation will find the user record with the primary key 1, and then delete it from the database.

Summary

ORM is an important component in Laravel. It provides a convenient way to operate the database and makes your code clearer and easier to understand. In this article, we have an in-depth understanding of the implementation principles of Laravel ORM, including how to connect to the database, define models, query data, insert data, update data, and delete data. By mastering this knowledge, we can better use Laravel ORM to implement database operations, thereby writing code faster and more reliably.

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