What is the principle of soft deletion in laravel

In laravel, soft deletion means that the data table records are not actually deleted from the database, but the representation status of the table records is marked as soft deletion, so that it can be filtered during query, so that The corresponding table record looks like it has been "deleted".

#The operating environment of this article: Windows 10 system, Laravel version 6, Dell G3 computer.

What is the principle of soft deletion in laravel

1. Delete the model

1.1 Use delete to delete the model

Deleting a model is very simple. First get the model instance to be deleted, and then call thedeletemethod:

$post = Post::find(5); if($post->delete()){ echo '删除文章成功！'; }else{ echo '删除文章失败！'; }

This method returnstrueorfalse.

1.2 Use destroy to delete the model

Of course, if the model ID to be deleted is known, you can delete it directly using a simpler methoddestroy:

$deleted = Post::destroy(5);

You can also delete multiple models by passing in multiple model IDs at one time:

$deleted = Post::destroy([1,2,3,4,5]);

Call thedestroymethod to return the number of deleted records.

1.3 Use the query builder to delete the model

Since it was mentioned earlier that the Eloquent model itself is a query builder, you can also use the query builder style to delete the model. For example, we want to To delete all articles with 0 views, you can use the following method:

$deleted = Models\Post::where('views', 0)->delete();

The return result is the number of deleted articles.

2. Soft deletion and its related implementation

2.1 Soft deletion implementation

The above deletion methods will record the data table Delete from the database. In addition, the Eloquent model also supports soft deletion.

The so-called soft deletion means that the data table records are not actually deleted from the database, but the identification status of the table records is marked as soft deletion, so that it can be filtered when querying, so that the corresponding table records It looks like it has been "deleted". Laravel uses a date field as the identification status. This date field can be customized. Here we usedeleted_at. If the corresponding model is soft-deleted, the value of thedeleted_atfield is the deletion time. , otherwise the value is empty.

To make the Eloquent model support soft deletion, some settings need to be made. First, use theSoftDeletestrait in the model class. This trait provides a series of related methods for soft deletion. For details, please refer to the source codeIlluminate\Database\Eloquent\SoftDeletes. In addition, you must also set$dateAttribute array, placedeleted_atin it:

        

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Then add thedeleted_atcolumn to the corresponding databaseposts, we use migration to implement, first execute the Artisan command:

php artisan make:migration alter_posts_deleted_at --table=posts

Then edit the generated PHP file as follows:

softDeletes(); }); } ...//其它方法 }

Then run:

php artisan migrate

This wayposts# There is adeleted_atcolumn in ##. Next, we write the test code in the controller:

$post = Post::find(6); $post->delete(); if($post->trashed()){ echo '软删除成功！'; dd($post); }else{ echo '软删除失败！'; }

http://laravel.app:8000/testin the browser, the page output is as follows:

$posts = Post::all(); dd($posts);

2.2 Query results contain soft-deleted models

withTrashedmethod on theSoftDeletestrait:

$posts = Post::withTrashed()->get(); dd($posts);

onlyTrashedmethod onSoftDeletes:

$posts = Post::onlyTrashed()->get(); dd($posts);

2.3 Soft Deletion Recovery

SoftDeletesProvidedrestoremethod:

Restore a single model

$post = Post::find(6); $post->restore();

Restore multiple models

Post::withTrashed()->where('id','>',1)->restore();

Restore all models

Post::withTrashed()->restore();

Restore associated query model

$post = Post::find(6); $post->history()->restore();

2.4 Forced deletion

forceDeletemethod provided bySoftDeletes:

$post = Post::find(6); $post->forceDelete();

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