Laravel Eloquent ORM in Bangla Part-Models Retrieving)

Laravel Eloquent provides convenient and readable methods to interact with the database, making it easy to obtain database data. Several data acquisition techniques are introduced below:

1. Get all records

Use the all() method to get all records in the table:

<code class="language-php">use App\Models\Post;

$posts = Post::all();</code>

This will return a Collection. You can access data using foreach loops or other collection methods:

<code class="language-php">foreach ($posts as $post) {
    echo $post->title;
}</code>

2. Get a single record

1. find() Method: Get a single record based on the primary key.

<code class="language-php">$post = Post::find(1);

if ($post) {
    echo $post->title;
}</code>

2. findOrFail() Method: Get a single record based on the primary key. If the record does not exist, a 404 exception will be thrown.

<code class="language-php">$post = Post::findOrFail(1);</code>

3. first() Method: Get the first record that meets the conditions.

<code class="language-php">$post = Post::where('status', 'published')->first();</code>

4. firstOrFail() Method: Get the first record that meets the conditions. If the record does not exist, a 404 exception will be thrown.

<code class="language-php">$post = Post::where('status', 'published')->firstOrFail();</code>

3. Use query conditions to filter records

Use where and other conditional statements to filter data.

1. where Method:

<code class="language-php">$posts = Post::where('status', 'published')->get();</code>

2. Multiple conditions:

<code class="language-php">$posts = Post::where('status', 'published')
             ->where('user_id', 1)
             ->get();</code>

3. orWhere Method:

<code class="language-php">$posts = Post::where('status', 'published')
             ->orWhere('status', 'draft')
             ->get();</code>

4. Select specific fields

Eloquent gets all fields by default. Use the select() method to select a specific field:

<code class="language-php">$posts = Post::select('title', 'content')->get();</code>

5. Pagination

Use the paginate() method to get data in pages:

<code class="language-php">$posts = Post::paginate(10);</code>

Show pagination links in Blade templates:

<code class="language-blade">{{ $posts->links() }}</code>

6. Data Chunking

When processing large amounts of data, memory usage can be effectively reduced:

<code class="language-php">Post::chunk(100, function ($posts) {
    foreach ($posts as $post) {
        echo $post->title;
    }
});</code>

7. Sorting results (Ordering)

Use the orderBy() method to sort in the specified order:

<code class="language-php">$posts = Post::orderBy('created_at', 'desc')->get();</code>

8. Limit and Offset

Use take() or limit() and skip() methods to limit the number of records fetched:

<code class="language-php">$posts = Post::take(5)->get(); // 获取前 5 条记录
$posts = Post::skip(10)->take(5)->get(); // 跳过前 10 条，获取接下来的 5 条</code>

9. Aggregate functions (Aggregates)

1. Count:

<code class="language-php">$count = Post::count();</code>

2. Maximum value:

<code class="language-php">$maxViews = Post::max('views');</code>

3. Minimum value:

<code class="language-php">$minViews = Post::min('views');</code>

4. Average:

<code class="language-php">$avgViews = Post::avg('views');</code>

5. Sum:

<code class="language-php">$totalViews = Post::sum('views');</code>

10. Customized relationship retrieval

Eloquent supports obtaining data from other models through relationships.

1. Eager Loading:

<code class="language-php">$posts = Post::with('comments')->get();</code>

2. Specify relationship:

<code class="language-php">$posts = Post::with(['comments', 'user'])->get();</code>

11. Raw Queries

Execute custom SQL queries using Laravel’s DB facade:

<code class="language-php">use App\Models\Post;

$posts = Post::all();</code>

These methods provide flexible data acquisition methods to meet various database operation needs. Please choose the appropriate method according to the actual situation.

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