laravel get method

Laravel is a modern PHP framework that is widely used for its concise syntax and powerful functions. Obtaining data and methods in Laravel is a very important topic, because during the development process, we often need to obtain data from the database or other services to complete business logic.

This article will introduce the relevant knowledge of acquisition methods in Laravel, including query constructor, ORM (Object Relational Mapping), Eloquent model, relational model, etc.

1. Query constructor

The query constructor is a convenient database query tool provided by Laravel, which can help us obtain data and perform various data operations. Using the query builder, we can easily query data and perform operations such as sorting, grouping, and aggregation of query results.

For example, when querying user data from the database, we can use the following code:

$users = DB::table('users')->get();

This line of code will get all user data from the data table named "users". We can also add other conditions to get specific data. For example, we can get all users older than 18 with the following code:

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

With the query builder, we can use many functions to perform complex queries. For example, we can use the groupBy method to group results by specific columns:

$users = DB::table('users')
            ->groupBy('account_id')
            ->having('account_id', '>', 100)
            ->get();

2. ORM

ORM (Object Relational Mapping) is a technology that maps data in a database to objects. Laravel's ORM is implemented based on the Eloquent model, which can map data in data tables to PHP objects or arrays, allowing us to easily perform data operations.

For example, when using ORM, we can get user data through the following code:

$users = AppUser::all();

This line of code will use the Eloquent model to get all user data from the user data table and map it into the User object. We can also add other conditions to get specific data. For example, we can use the where method to get all users older than 18:

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

3. Eloquent model

The Eloquent model is a core concept in Laravel, which provides us with a way to access the database. methods and properties. When using an Eloquent model, we need to define a model class and map it to a data table in the database. We can then use the model instance to access the data in the database.

For example, we can create a User model class through the following code:

<?php

namespace App;

use IlluminateDatabaseEloquentModel;

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

In this model class, we specify the data table as "users", so that Laravel knows that we want to Which data table this model is associated with. Then, we can use the following code to get user data:

$users = User::all();

This line of code will get all user data from the data table corresponding to the User model and map it to the User object. We can also add other conditions to get specific data. For example, we can use the where method to get all users older than 18:

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

4. Relational model

In many applications, there are often associated relationships between data (such as one-to-many, one-to-many, many-to-many, etc.). The Eloquent model in Laravel can easily handle these relationships. Through the relationship model, we can easily obtain the associated data in the database.

For example, in a blogging application, we might have a Post model and a Comment model. A Post may have multiple Comments, so we need to establish a one-to-many relationship. We can define this relationship in the Post model using the following code:

<?php

namespace App;

use IlluminateDatabaseEloquentModel;

class Post extends Model
{
    protected $table = 'posts';

    public function comments()
    {
        return $this->hasMany(Comment::class);
    }
}

In this code, we define a comments method that returns all Comments carried by this Post. In the Comment model, we also need to define a method to specify which Post the Comment belongs to:

<?php

namespace App;

use IlluminateDatabaseEloquentModel;

class Comment extends Model
{
    protected $table = 'comments';

    public function post()
    {
        return $this->belongsTo(Post::class);
    }
}

Now, we can get the comments of a certain article through the following code:

$post = Post::find(1);

$comments = $post->comments;

This line of code will Returns all Comments contained in the Post with id 1.

Summary

The above is the relevant knowledge about the acquisition method in Laravel. Query builder, ORM, Eloquent model and relational model, these powerful functions provide us with convenient methods to obtain and process data in development. Whether you're getting data from a database, a cache, or another service, there are many convenient ways to do it in Laravel. By mastering this knowledge, we can implement complex business logic more easily.

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