laravel migration add foreign key to existing table

• Create foreign key to an existing table in laravel 8

  //Create migration file
  php artisan make:migration add_user_id_to_posts_table --table=posts
  
  //Create table structure using column type in the generated migration file
  //database\migrations\<2021_07_26_032616>_add_user_id_to_posts_table.php
  public function up()
  {
      Schema::table('posts', function (Blueprint $table) {
          $table->foreignId('user_id')->constrained();
      });
  }
  
  /**
      * Reverse the migrations.
      *
      * @return void
      */
  public function down()
  {
      Schema::table('posts', function (Blueprint $table) {
          $table->dropForeign(['user_id']);
      });
  }
  
  //Run artisan command to create a foreign key
  php artisan migrate
  

  Laravel 8 has a foreignId() column type in migration schema builder. Which is used to create a foreign key in laravel with an UNSIGNED BIGINT equivalent column.

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