This paper illustrates the usage of polymorphic Association in laravel 5.1 framework model. Share with you for your reference, as follows:
What is polymorphic association? You can see from an example: for example, comments can belong to video or article. When there is a need to get video data from the comment table, polymorphic association is required.
A simple one sentence summary: one table corresponds to two tables.
1 realize polymorphic Association
1.1 structure of article table
public function up()
{
Schema::create('articles', function (Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->text('body');$table->timestamps();
});
}
1.2 video table structure
public function up()
{
Schema::create('videos', function (Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->text('description');
$table->timestamps();
});
}
1.3 comment form structure
public function up()
{
Schema::create('comments', function (Blueprint $table) {
$table->increments('id');
$table->text('content');
$table->integer('item_id');
$table->string('item_type');
$table->timestamps();
});
}
↑ you need to specify Item here_ ID and item_ Type single introduction to item_ Type is mainly different from the table associated with it. Here, it has only two values: app \ article or app \ video.
1.4 writing polymorphic associations
Article and video:
public function comments()
{
/**
*Second parameter: if your prefix is item_ Then write item. If it's something else, write something else.
*The third parameter: item_ type
*The fourth parameter: item_ id
*The fifth parameter: the key associated with that table
*(all but the second parameter above can be omitted)
*/
return $this->morphMany(Comment::class, 'item', 'item_type', 'item_id', 'id');
}Comment：
public function video()
{
/**
*All three parameters can be omitted, but K suggests you write them all
*/
return $this->morphTo('item', 'item_type', 'item_id');
}use:
Route::get('/', function () {
$video = App\Video::find(8);
foreach ($video->comments as $comment) {
echo $comment->id . ": " . $comment->item_type;
}
});
For more information about laravel, readers who are interested can see the special topics on this site: introduction and advanced tutorial of laravel framework, summary of PHP excellent development framework, introduction to PHP object-oriented programming, introduction to PHP + MySQL database operation, and summary of common database operation skills for PHP
I hope this article will be helpful to your PHP Programming Based on laravel framework.