Yii 2.0 ActiveRecord: A Deep Dive into Object-Relational Mapping
Yii 2.0's ActiveRecord provides a robust Object-Relational Mapping (ORM) interface, simplifying database interactions. This approach, common in frameworks like Laravel and Ruby on Rails, offers features like mass assignment, validation, and scenario-based behavior. Let's explore its capabilities and advanced features.
Core Functionality (Inherited from yiibaseModel):
-
Attributes: Model data is stored in publicly accessible attributes. Mass assignment is facilitated by assigning arrays to the
attributes
property, leveraging the__set()
andsetAttributes()
methods inherited fromyiibaseComponent
. Attribute retrieval similarly uses__get()
andgetAttributes()
. Attribute labels, crucial for user interfaces, are defined for display purposes. -
Validation: The
rules()
method defines validation rules for attributes, ensuring data integrity. By default, only "safe" attributes (those with defined validation rules) are mass-assignable. -
Scenarios: Scenarios allow defining different validation and data handling rules depending on the context (e.g., registration vs. login). This enhances flexibility and maintainability.
Creating an ActiveRecord Model:
The example uses a simple blog structure (see image above). The Articles
model, generated using Gii, demonstrates the basic structure:
namespace app\models; use Yii; class Articles extends \yii\db\ActiveRecord { // ... (tableName(), rules(), attributeLabels() as shown in the original text) ... public function getAuthors() { return $this->hasOne(Authors::className(), ['ID' => 'AuthorsID']); } public function getArticlestags() { return $this->hasMany(Articlestags::className(), ['ArticlesID' => 'ID']); } public function getTags() { return $this->hasMany(Tags::className(), ['ID' => 'TagsID']) ->viaTable(Articlestags::tableName(), ['ArticlesID' => 'ID']); } }
Note the addition of the getTags()
method, which defines the many-to-many relationship with Tags
via the Articlestags
junction table.
Advanced Usage:
Yii 2.0 ActiveRecord enhances the base functionality with several advanced features:
-
Dirty Attributes: Track changes to model attributes using
getDirtyAttributes()
,isAttributeChanged()
, andmarkAttributeDirty()
. This is invaluable for efficiently updating database records. -
Arrayable: The
toArray()
method, inherited via theArrayable
trait, converts the model to an array.fields()
andextraFields()
allow customizing the array's content, including calculated fields. For example, adding a comma-separated string of tags:
namespace app\models; use Yii; class Articles extends \yii\db\ActiveRecord { // ... (tableName(), rules(), attributeLabels() as shown in the original text) ... public function getAuthors() { return $this->hasOne(Authors::className(), ['ID' => 'AuthorsID']); } public function getArticlestags() { return $this->hasMany(Articlestags::className(), ['ArticlesID' => 'ID']); } public function getTags() { return $this->hasMany(Tags::className(), ['ID' => 'TagsID']) ->viaTable(Articlestags::tableName(), ['ArticlesID' => 'ID']); } }
- Events: ActiveRecord triggers events at various stages of its lifecycle (e.g.,
beforeValidate()
,afterSave()
). These allow customizing behavior without modifying core model code. For example, automatically updatingLastEdited
:
public function extraFields() { return [ 'tagsString' => function () { return implode(', ', array_map(function ($tag) { return $tag->Tag; }, $this->tags)); }, ]; }
- Behaviors: Behaviors add functionality to models without modifying their code. Yii provides built-in behaviors like
BlameableBehavior
(tracking creators/updaters) andTimestampBehavior
(automatic timestamps). Attaching these behaviors:
public function beforeValidate() { $this->LastEdited = new \yii\db\Expression('NOW()'); return parent::beforeValidate(); }
-
Transactional Operations: The
transactions()
method defines which operations should be wrapped in database transactions, ensuring data consistency.
Conclusion:
Yii 2.0 ActiveRecord provides a powerful and flexible ORM, significantly simplifying database interactions. The advanced features, including dirty attributes, events, behaviors, and transactional operations, enhance its capabilities and adaptability to complex scenarios. This detailed exploration highlights its strengths and demonstrates how to leverage its full potential.
The above is the detailed content of Yii 2.0 ActiveRecord Explained. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

ToversionaPHP-basedAPIeffectively,useURL-basedversioningforclarityandeaseofrouting,separateversionedcodetoavoidconflicts,deprecateoldversionswithclearcommunication,andconsidercustomheadersonlywhennecessary.StartbyplacingtheversionintheURL(e.g.,/api/v

TosecurelyhandleauthenticationandauthorizationinPHP,followthesesteps:1.Alwayshashpasswordswithpassword_hash()andverifyusingpassword_verify(),usepreparedstatementstopreventSQLinjection,andstoreuserdatain$_SESSIONafterlogin.2.Implementrole-basedaccessc

Proceduralandobject-orientedprogramming(OOP)inPHPdiffersignificantlyinstructure,reusability,anddatahandling.1.Proceduralprogrammingusesfunctionsorganizedsequentially,suitableforsmallscripts.2.OOPorganizescodeintoclassesandobjects,modelingreal-worlden

PHPdoesnothaveabuilt-inWeakMapbutoffersWeakReferenceforsimilarfunctionality.1.WeakReferenceallowsholdingreferenceswithoutpreventinggarbagecollection.2.Itisusefulforcaching,eventlisteners,andmetadatawithoutaffectingobjectlifecycles.3.YoucansimulateaWe

To safely handle file uploads in PHP, the core is to verify file types, rename files, and restrict permissions. 1. Use finfo_file() to check the real MIME type, and only specific types such as image/jpeg are allowed; 2. Use uniqid() to generate random file names and store them in non-Web root directory; 3. Limit file size through php.ini and HTML forms, and set directory permissions to 0755; 4. Use ClamAV to scan malware to enhance security. These steps effectively prevent security vulnerabilities and ensure that the file upload process is safe and reliable.

Yes, PHP can interact with NoSQL databases like MongoDB and Redis through specific extensions or libraries. First, use the MongoDBPHP driver (installed through PECL or Composer) to create client instances and operate databases and collections, supporting insertion, query, aggregation and other operations; second, use the Predis library or phpredis extension to connect to Redis, perform key-value settings and acquisitions, and recommend phpredis for high-performance scenarios, while Predis is convenient for rapid deployment; both are suitable for production environments and are well-documented.

In PHP, the main difference between == and == is the strictness of type checking. ==Type conversion will be performed before comparison, for example, 5=="5" returns true, and ===Request that the value and type are the same before true will be returned, for example, 5==="5" returns false. In usage scenarios, === is more secure and should be used first, and == is only used when type conversion is required.

The methods of using basic mathematical operations in PHP are as follows: 1. Addition signs support integers and floating-point numbers, and can also be used for variables. String numbers will be automatically converted but not recommended to dependencies; 2. Subtraction signs use - signs, variables are the same, and type conversion is also applicable; 3. Multiplication signs use * signs, which are suitable for numbers and similar strings; 4. Division uses / signs, which need to avoid dividing by zero, and note that the result may be floating-point numbers; 5. Taking the modulus signs can be used to judge odd and even numbers, and when processing negative numbers, the remainder signs are consistent with the dividend. The key to using these operators correctly is to ensure that the data types are clear and the boundary situation is handled well.
