Where is the model layer of Laravel

Laravel is a popular PHP web application framework that is widely used to build efficient, scalable and easy-to-maintain web applications. One of the key components is the model layer, which is the core component used to manage application data. In Laravel, the model layer plays an extremely important role. This article will introduce where Laravel's model layer is and analyze it in detail.

1. Overview of Laravel’s model layer

In the MVC (Model-View-Controller) framework, the model layer (Model) is the core component used to handle data and database interaction. In Laravel, the model layer inherits the Eloquent ORM (Object-Relational Mapping) implementation, which simplifies data interaction and provides convenient methods for database operations.

2. Laravel’s model layer location

In Laravel, all model objects are in the Models subdirectory under the app directory. If your application uses Laravel's default directory structure, these model files should be found in the app/Models directory.

For example, if we have a model named User, then it should correspond to the file app/Models/User.php. In this file, we can define corresponding data tables, relationships, data operations, etc.

3. Functions of Laravel’s model layer

Laravel’s model layer provides a series of powerful functions, including the following aspects.

1. Data table mapping

In Laravel, model classes are usually mapped to database tables, that is to say, the objects of the model class represent data in a database table . In the model class, we can specify the table name using the $table attribute, so Laravel will automatically map the model object to the table.

For example, if we have a model named User, we can specify the data table to be mapped like this:

class?User?extends?Model
{
????/**
?????*?該模型關(guān)聯(lián)的數(shù)據(jù)庫表
?????*
?????*?@var?string
?????*/
????protected?$table?=?'users';
}

2. Define the association

The association relationship in the model layer refers to the association relationship between model objects, including one-to-one, one-to-many, many-to-many and other types. In Laravel, we can use the officially provided association relationship method to define these relationships.

For example, if we have two models, Order and OrderItem, and one order can contain multiple order items, then we can define the association between them like this:

class?Order?extends?Model
{
????/**
?????*?訂單所包含的訂單項
?????*/
????public?function?orderItems()
????{
????????return?$this->hasMany(OrderItem::class);
????}
}

class?OrderItem?extends?Model
{
????/**
?????*?所屬訂單
?????*/
????public?function?order()
????{
????????return?$this->belongsTo(Order::class);
????}
}

3. Use models for data operations

In the model layer, we can also use model objects to perform data operations, such as adding, querying, deleting or updating data, etc. In Laravel, these operations are included in the Eloquent ORM.

For example, if we want to get all the order items of an order, we can use the Model::find() method to get the order object, and then call the orderItems() method to get all its order items:

$order?=?Order::find(1);
$orderItems?=?$order->orderItems();

4. Customized accessors and modifiers

Laravel’s model layer also allows us to customize accessors and modifiers to operate data more flexibly. Accessors are used to format a property when it is retrieved from the model, and modifiers operate on a property when it is set.

For example, we can define an accessor in the User model to get the full name of the user:

class?User?extends?Model
{
????/**
?????*?訪問器，獲取用戶的全名
?????*
?????*?@return?string
?????*/
????public?function?getFullNameAttribute()
????{
????????return?$this->first_name?.?'?'?.?$this->last_name;
????}
}

In this way, we can get the full name of the user object like this:

$user?=?User::find(1);
$fullName?=?$user->full_name;?//?'John?Doe'

Of course, the same applies to modifiers, just name the method starting with set.

4. Summary

Laravel’s model layer is the core component that handles data and database interaction, and plays an extremely important role. In Laravel, all model objects are in the Models subdirectory under the app directory. We can define corresponding data tables, relationships, data operations, etc. in the model class. These model classes provide rich functionality, including data table mapping, defining relationships, using the model for data manipulation, and using accessors and modifiers to customize data access and modification. Proficient in these functions can make it easier for us to manage and process data in applications.

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