When using the model to perform CRUD operations in Yii, the following steps need to be followed: 1. Create a record: Instantiate the model, assign attributes and call save(); 2. Read data: Use the find() method to obtain records in combination with query conditions; 3. Update records: query first and then modify attributes and save; 4. Delete records: Call delete() or deleteAll(). Pay attention to verification, secure assignment and soft deletion policies to ensure correct and secure operation.

In Yii, performing CRUD operations using models is straightforward once you understand the basic patterns. The framework provides a solid foundation for working with database records through ActiveRecord-style models.

Here's how to handle each of the CRUD operations effectively.

Creating a New Record

To create a new record in the database, you'll typically use your model class and assign values to its attributes before saving it.

 $model = new Post(); // assuming you have a Post model
$model->title = 'My First Post';
$model->content = 'This is the content.';
$model->save();

A few things to note:

• Always validate your data before saving by calling $model->validate() or just rely on save() which does validation by default.
• If you're getting input from a form (like in a controller action), you can use $model->load(Yii::$app->request->post()) to populate the attributes.

If you're handling file uploads or more complex forms, make sure to set the proper encoding type in your form and process additional fields accordingly.

Reading Data from the Database

For reading data, Yii offers several methods depending on what you need:

• To get all records:

   $posts = Post::find()->all();

• To get a single record by primary key:

   $post = Post::findOne($id);

• To find by other conditions:

   $post = Post::find()->where(['status' => 'published'])->one();

You can also chain methods like orderBy() , limit() , or with() for eager loading related models.

If you're building a listing page, you'll often combine these with pagination:

 $query = Post::find();
$pagination = new Pagination(['totalCount' => $query->count()]);
$posts = $query->offset($pagination->offset)->limit($pagination->limit)->all();

Updating an Existing Record

To update a record, first fetch it from the database, change the attributes, then call save() again.

 $post = Post::findOne($id);
if ($post) {
    $post->title = 'Updated Title';
    $post->save();
}

Like with creating, you can use load() if you're handling form submissions:

 if ($model->load(Yii::$app->request->post()) && $model->save()) {
    // redirect or show success message
}

Be careful with mass assignment — make sure to define safe attributes in the rules() method of your model to avoid security issues.

Deleting a Record

Deleting is simple but permanent, so always be cautious.

 $post = Post::findOne($id);
if ($post) {
    $post->delete();
}

Alternatively, you can delete multiple records at once:

 Post::deleteAll(['status' => 'draft']);

Keep in mind that delete() doesn't return a model anymore — it returns the number of affected rows. Also, if you want to soft-delete instead of removing data permanently, consider adding a deleted_at column and override the delete behavior.

That's basically how you perform CRUD operations in Yii using models. It's not overly complicated, but there are enough nuances — especially around validation, mass assignment, and relationships — that it's worth spending time understanding the documentation and best practices.

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