Laravel 基础知识

Laravel / Lumen 阅读量

记录Laravel的一些基础知识…

原文地址: Head into Laravel

准备

全局安装 Composer

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curl -sS https://getcomposer.org/installer | php -- --install-dir=bin --filename=composer

# Or
# php -r "readfile('https://getcomposer.org/installer');" | php

# Or manually rename composer.phar to composer and link the composer binary file to $PATH

安装 Laravel/Lumen

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composer global require laravel/installer
composer global require "laravel/lumen-installer=~1.0"

vim ~/.zshrc

# add `~/.composer/vendor/bin` to the $PATH

source ~/.zshrc

自带服务器运行

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laravel new site
# or Lumen: `lumen new site`

cd site
php artisan serve --port 8888

注意

  • 安装指定版本的 Laravel/Lumen
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composer create-project laravel/laravel blog "5.1.*"

Blade

布局视图

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<!-- layouts/main.blade.php -->
@yield('title')
@yield('header')
@yield('content')
@yield('footer')

普通视图

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<!-- index.blade.php -->
@extends('layouts.main')
@section('title', 'PAGE NAME')
@section('header')
  <!-- header detail -->
  {{ $variable->attr }}
<!-- Include sub view -->
@include('shared.navbar')
@section('content')
  <!-- content detail -->
	@if (...)
	    {{ time() }}
	@elseif (...)
	    {{ some php code here }}
	@else
	    {{ php }} or html all ok
  	@endif
      
@section('footer')
  <!-- footer detail -->
@stop
<!-- or @endsection -->

更多例子参照(这里, 这里)

Data

将数据传递到视图

  • 数组格式
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Route::get('/', function () {
    $data = [1, 2, 3] ;
    return view('welcome', ['data' => $data]);
});
  • compact()
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Route::get('/', function () {
    $data = [1, 2, 3] ;
    return view('welcome', compact('data'));
});
  • with()
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Route::get('/', function () {
    $data = [1, 2, 3] ;
    return view('welcome')->with('data' => $data);
});
  • 动态方法
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Route::get('/', function () {
    $data = [1, 2, 3] ;
    return view('welcome')->withData($data);
});

数据库驱动

  • config/database.php

找到 'default' => env('DB_CONNECTION', 'mysql') ,修改成需要的驱动就可以了.

If use sqlite(file based database for small project), please comment the DB_* fields in .env file.

Migration

Migration: The Version Controll of Database

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# 1. define the table we want to create
php artisan make:migration create_users_table --create=user

# 2. custom the table structure in /database/migrations/DATATIME_create_user_table.php@up() function

# 3. actual create the table we defined before into our configured database
php artisan migrate

# 4. delete tables if we want modify it, migrate it to others env, etc.
php artisan migrate:rollback

Tinker

你的项目的所有PHP laravel方法能够被执行在Tinker

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php artisan tinker

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

命名空间等于文件夹结构。

命名空间的回顾

在像PHP这样的编程语言中 命名空间用于放置类，避免类名相同时的歧义。

在laravel，定位的两种方法的类：

  • use use \Path\To\Class; before the class defination.
  • use \Classname in the function block.

注意，当您不使用任何命名空间时，PHP将在当前命名空间中搜索您需要的类。

查询生成器

这是Laravel一个传统与数据层交互方式。

按照这里的演示：这里 AND 这里

Eloquent: ORM of Laravel

简单地说，它只是MVC设计模式中的M层。

不同的是，它是在PHP的活动记录实现与数据库表进行交互，而不是使用传统的查询生成器。

其结果是，每个表有一个模型，模型代表表和表的增删改查选项更方便和愉快的模型。

在Laravel中的使用步骤:

  • 1.Create table via make:migration
  • 2.Insert data into the table
  • 3.Make a Model reference to the table
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php artisan make:model Models/User -m # --migration

- m 选项仅用于我们没有创建此模型响应的表时。

注意这里有一条规则：

Model name must be singular, but table name must be plurals.

模型名称必须是单数，但表名必须是复数。

For example, model name of table histories should be history.

  • 4.Using Model in controller

For example, we have created a table users, and a model User in namespace App\Models\User, contents of App\Http\routes.php like these:

在路由中使用:

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Route::get('users', 'Users@index');

# below two routes are same intend, just for explain here
# use only one way if you like

// Will show specific user by id
Route::get('users/{id}', 'Users@show');

// Will show specific user by instance
Route::get('users/{user}', 'Users@show');

在控制器中使用:

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<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Models\User;

class Users extends Controller
{
    /**
     * get all users
     */
    public function index()
    {
        return User::all() ;   // Automatically JSON Response
    }
    
    /**
     * 1. show specific user by id
     * !!! param name `$id` don't have to response to the `{id}` in routes defination
     */
    public function show($id)
    {
        $user = User::find($id) ;    // Also JSON if has the result
        return $user ? $user : 'user not found' ;
    }
    
    /**
     * 2. show specific user by instance
     * !!! param name `$user` must response to the `{user}` in routes defination
     */
    public function show(User $user)
    {
        return $user ;    // JSON
    }
}
  • 5.Pass the result data to blade views when necessary

只需要注意: .是连接/目录的意思, 比如 view(users.show) 意思是 resources/views/users/show.blade.php

Eloquent

举个简单的例子 我们创建表: users, cards, notes

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php artisan make:model Models\User -m
php artisan make:model Models\Card -m
php artisan make:model Models\Note -m

我们所定义的每个up()方法：

在 database/migrations/

  • CreateUsersTable:
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Schema::create('users', function (Blueprint $table) {
    $table->increments('id');
    $table->string('name');
    $table->timestamps();
});
  • CreateCardsTable:
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Schema::create('cards', function (Blueprint $table) {
    $table->increments('id');
    $table->integer('user_id')->unsigned()->index();
    $table->string('title');
    $table->timestamps();
});
  • CreateNotesTable:
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Schema::create('notes', function (Blueprint $table) {
    $table->increments('id');
    $table->integer('card_id')->unsigned()->index();
    $table->text('content');
    $table->timestamps();
});

显然, 他们之间的关系: user has cards, cards has notes. 测试前, 运行迁移:

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php artisan migrate

Ok then. How to define the relationship with Eloquent are basically the same, so we take the cards has notes relationship to explain how it works.

好吧, 怎么使用Eloquent关联模型基本一致, 所以我们就使用 cards has notes 的关系来解释.

Get/Query

  • No Eloquent
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php artisan tinker
# 1. Prepare one card whose id = 1
$card = new App\Models\Card;
$card->user_id = 1;    // assume it's 1 here
$card->title   = '1st card';
$card->save();

# 2. Create a note with it's card_id = 1
$note = new App\Models\Note;
$note->card_id = 1;
$note->content = '1st note';
$note->save();

Yes, it just manually relate their relationship. It’s a little bit inelegant.

  • With Eloquent

    • define the notes() method in Card Model
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    public function notes()
    {
          return $this->hasMany(Note::class);    // either `Note::class` or `\App\Models\Note`
    }
      
      
    public function path()
    {
          return '/cards/' . $this->id;
    }

    当我们使用 \App\Models\Notes 将转化成对象, 使用 Notes::class将转化成类的字符串表示形式。

    • call the notes() method in Card Model instance
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    php artisan tinker

    $card = App\Models\Card::first()

    $card->notes->first()        # as collection

    # Or
    # $card->notes[0]        # as array

    # Or
    # $card->notes()->first()    # as object

    集合和对象的不同在于最后的查询sql

    通过一个测试证明下:

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    php artisan tinker   # refresh the modifications in project

    # Setup a listener when query event occurs
    >>> DB::listen(function ($query){ echo $query->sql; }

    >>> $card = new App\Models\Card::first()
    select * from "cards" limit 1;

    # First execute the get-card-notes query
    >>> $card->notes
    select * from "notes" where "notes"."card_id" = ? and "note"."card_id" is not null

    # Re-execute the same query
    >>> $card->notes
    # You will see nothing here because the last query result is stored in the $card object and fetch them directly from object rather than the database

    # Check if the $card object has the notes relationships here
    >>> $card
    # You will see the notes of this card here

    # Check if notes relationship still exists after we refresh the object
    >>> $card->fresh()
    select * from "cards" where "id" = ? limit 1
    >>> $card
    # You wil note see the notes of this card here any more because the resuls cache are erased after `fresh()`

    # If we use as collection, the sql of get first note record might be like this:
    >>> $card->fresh()->notes->first()
    select * from "cards" where "id" = ? limit 1
    select * from "notes" where "notes"."card_id" = ? and "notes"."card_id" is not null

    # If we use as object method, the sql of get first note record might be like this:
    >>> $card->fresh()->notes()->first()
    select * from "cards" where "id" = ? limit 1
    select * from "notes" where "notes"."card_id" = ? and "notes"."card_id" is not null limit 1

    测试结果和上面的结论一致.

hasMany and belongsTo

Moreover, we can say that note also belongs to card. So here is how eloquent deal with this belongs-to relationship here.

简单来说:就是 谁拥有谁==谁属于谁

    • define the card() method in Note Model:
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    public function card()
    {
      return $this->belongsTo(Card::class);
    }
    • call the card method in Note Model instance
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    php artisan tinker

    $note = App\Models\Note::first()

    $note->card

Be aware that: hasMany() related method is notes(), which is resonable because one card can has many notes, and belongsTo() related method is card(), which is resonable because one note only belongs to one card.

注意到: hasMany() 对应的方法是 notes (复数),是因为 一张卡可以有很多笔记, belongTo 对应的方法是 card() (单数),是因为 一个笔记只属于一张卡

你不应该创建方法名为 note() 或 cards()，因为它没有任何意义，必须回应你叫它什么方法。

记住，hasmany() 和复数的方法有关，belongsto()和单数的方法相关。

Create/save

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php artisan tinker

# Create a new Note
$note = new App\Models\Note
$nots->content = 'second note'

# Decide which card to associate with
$card = App\Models\Card::first()

# Save a exists note by `save()`
$card->notes()->save($note)    # we cann't use $card->notes->save() here

# Or create a new note by `create()`
$card->notes()->create(['content'=>'third note'])    # make sure that `content` is fillable in Note Model

# See the new note associated with first card
$card->notes
# Yout will see new note was already in $card object

Notice that here we didn’t set the card_id for $note, because eloquent automatically did this for us.

When we creating new record, we cann’t use collections any more, because it is only used for query-like operations.

此外，当我们通过 create()直接创建一个新的记录, 需要某个字段批量赋值如:content, 需要在$fillable定义.

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class Note extends Model
{
    protected $fillable = ['content'];
    
    public function card()
    {
    	return $this->belongsTo(Card::class);
    }
}

$fillable 可以作为设置被批量赋值的属性的「白名单」, 这也是Laravel中避免攻击的方法之一.

Form

基于之前的例子:我们有 resources/views/cards/show.blade.php 

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@extends('layouts.main')
@section('title', 'show card')
@section('content')
<div class="row">
	<div class="col-md-6">
		<h1>
			{{ $card->title }}
		</h1>
		<ul class="list-group">
			@foreach ($card->notes as $note)
				<li class="list-group-item">
					{{ $note->content }}
				</li>
			@endforeach
		</ul>
		<hr>
		<h2>
			Add More Notes Here
		</h2>
		<form method="POST" action="/cards/{{ $card->id }}/notes">
		<input type="hidden" name="_token" value="{{ csrf_token() }}">
			<div class="form-group">
				<textarea name="content" class="form-control"></textarea>
			</div>
			<div class="form-group">
				<button type="submit" class="btn btn-primary">
					Add Note
				</button>
			</div>
		</form>
	</div>
</div>
@stop

创建 routes.php:

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Route::post('cards/{card}/notes', 'Notes@store');

创建控制器 Notes@store:

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public function store(Request $request, Card $card)
{
    // return $request->all();
    // return \Request::all();
    // return request()->all();
    // return $card;
    
# 1
    // $note = new Note;
    // $note->content = $request->content;
    // $card->notes()->save($note);
    
    # 2
    // $card->notes()->save([
    //     new Note([
    //         'content' => $request->content
    //         ])
    //     ]);
    
    # 3
    // $card->notes->create([
    //         'content' => $request->content
    //     ]);
    
    # 4
    $card->notes()->create(request()->all());      
  
    // return \Request::to('path/to/new/uri');
    // return redirect()->to('path/to/new/uri');
    return back();
}

注意:

    • If you want use eloquent as an instance, the param name $card must equals to the route catch name {card}, here card equals card. Or $card in method will be nothing, which is unexpected.
    • When we use create() to insert an relationship, we must make sure that we had stipulated the $fillable in related model, as we talked before.

Since card and note has relationship here, so we can add a method to describle more clearer what we want to do, we can add a method addNote() in model Card, like this:

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public function addNote(Note $note)
{
    $this->notes()->save($note);
}

最后, 控制器中 Notes@store():

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public function store(Request $request, Card $card)
{
    $card->addNote(
        new Note($request->all())
    );
    
    return back();
}

RESTful Principles Review

RESTful接口整个说明本表：

资源控制器

此外，由于浏览器只直接理解GET和POST方法，所以遵循REST约定可以像这样做:

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<form method="POST">
  {{ method_field('PATCH | DELETE | PUT') }}
  <!-- which equals to: -->
  <!-- <input type="hidden" name="method" value="PATCH"> -->
  <!-- more form elements -->
</form>

Update And Eager Loading

预先加载是避免大量的数据库查询该对象的数据可以得到一个查询通过建立laravel模型关系的有效途径。

Before we using eager loading, if we want to get both the notes of one card, and the user this card belongs to, we may query N+1 times like this (notes table must has fileds named with user_id and card_id):

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public function showByInstance(Card $card)
{
    return $card->notes[0]->user;
}

这里需要查询两次, 这是低效的

使用预加载,我们可以将两次查询合并成一次,就像:

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public function showByInstance(Card $card)
{
    return $card->load('notes.user');    // notes means Card@notes() user means Note@user()
    
    # Or
    // return $card->with('notes.user');
    
    # Or only load notes of this card
    // return $card->load('notes');
    // return $card->with('note')->find(1);    // 1 means this id of the card we want to find
}

Validation

    • Form input
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public function addNote(Request $request, Card $card)
{
    $this->validate($request,[
        'content' => 'required|min:10'
    ]);     // Controller => ValidatesRequests@validate
}
    • CSRF: See detail in FAQ.
    • Middleware
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Route::group([
    'middleware' => ['web'],
], function () {
    Route::post('cards/{card}/notes', 'Cards@addNote');
    // Route::post('cards/{card}/notes', 'Notes@store');
    // More routes
});
    • Errors

每个视图都可以共享($errors)错误变量。

    • old('field_name')

When form check fails, the preview wrong data are withInput() in the redirect, and we can put it into the right elements.

通过 old(),获取上一次输入的内容.

FAQ

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composer dump-autoload
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<input type="hidden" name="_token" value="{{ csrf_token() }}">
<!-- Or -->
{{ csrf_field() }}
<!-- Or set into meta tag -->
<meta name="csrf-token" content="{{ csrf_token() }}">
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PUT = replace the ENTIRE RESOURCE with the new representation provided (no mention of related resources in the spec from what i can see)
// 用所提供的新表示替换整个资源（在我所看到的规范中没有提到相关资源）

PATCH = replace parts of the source resource with the values provided AND|OR other parts of the resource are updated that you havent provided (timestamps) AND|OR updating the resource effects other resources (relationships)

重置和刷新命令列表

  • php artisan clear-compiled: 删除已编译的类文件

  • php artisan auth:clear-resets : 刷新过期密码重置令牌

  • php artisan cache:clear: 刷新应用程序缓存

  • php artisan config:clear: 删除配置缓存文件

  • php artisan migrate:refresh: 重置并重新运行所有迁移

Same with migrate:rollback, they will erase the data in database.

  • php artisan migrate:reset: 回滚所有数据库迁移

  • php artisan queue:flush: 刷新所有失败的队列作业

  • php artisan queue:forget: 删除失败的队列作业

  • php artisan route:clear: 删除路由缓存文件

  • php artisan view clear: 清除所有的编译文件

参考(References)

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