Laravel Eloquent Model Retrieval: Easily Get Database Data

Eloquent ORM provides a simple and easy-to-understand way to operate a database. This article will introduce various Eloquent model search techniques in detail to help you obtain data from the database efficiently.

1. Get all records

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

 <code class="php">use App\Models\Post; $posts = Post::all();</code>

This returns a collection. You can access data using foreach loop or other collection methods:

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

2. Get a single record

• find() method: Get a single record through the primary key.

 <code class="php">$post = Post::find(1); if ($post) { echo $post->title; }</code>

• findOrFail() method: If the record does not exist, a 404 HTTP exception is thrown.

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

• first() method: Get the first record that meets the criteria.

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

• firstOrFail() method: If no record matching the criteria is found, a 404 HTTP exception is thrown.

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

3. Search records based on conditions

where clause and other conditions are used to filter specific records.

• Single condition:

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

• Multiple conditions:

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

• orWhere clause:

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

4. Select a specific column

select() method is used to specify the columns to be retrieved:

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

5. Pagination

paginate() method is used to paginate the results:

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

Show paging links in the Blade template:

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

6. Block processing

chunk() method is used to process large amounts of data and reduce memory usage:

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

7. Sort

orderBy() method is used to sort the results:

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

8. Limits and Offsets

take() or limit() and skip() are used to get a specified number of records:

 <code class="php">$posts = Post::take(5)->get(); // 獲取前5 條記錄$posts = Post::skip(10)->take(5)->get(); // 跳過前10 條，獲取接下來(lái)的5 條</code>

9. Aggregation method

Eloquent provides a variety of aggregation methods:

• count() : count number of records
• max() : Get the maximum value
• min() : Get the minimum value
• avg() : Get the average
• sum() : Get the sum

10. Retrieval of association model

The Eloquent relationship allows easy retrieval of data from an associated model:

• Urgent loading:

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

• Multiple associations:

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

11. Native SQL Query

For complex queries, native SQL queries can be used:

 <code class="php">use Illuminate\Support\Facades\DB; $posts = DB::select('SELECT * FROM posts WHERE status = ?', ['published']);</code>

By mastering the above techniques, you can use Laravel Eloquent to retrieve database data flexibly and efficiently. Remember to choose the most appropriate method according to actual needs to improve the readability and performance of your code.

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