Laravel 5 - 将列和外键添加到包含数据的现有表中

Question

I am very new at Laravel! But I'm trying. Here is were I could use some help;

I have a posts table. I have a user table. But I forgot to add a foreign key in the posts table that links to the user id.

The create users table migration:

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateUsersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->string('email')->unique();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('users');
    }
}

The create posts table migration:

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreatePostsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('posts', function (Blueprint $table) {
            $table->increments('id');
            $table->string('title');
            $table->text('body');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('posts');
    }
}

I have created the new migration file:

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class AlterTablePostsAddForeignUser extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
      Schema::table('posts', function (Blueprint $table) {
          // I HAVE NO IDEA WHAT TO DO NEXT
      });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        //
    }
}

I have no idea how to fill up the "public function up()" method here! If anyone can help! It will be much appreciated!

Answer 1

I tried this and this worked for me.

Schema::table('posts', function (Blueprint $table) {
      $table->integer('user_id')->nullable()->unsigned();
      $table->foreign('user_id')->references('id')->on('users');
 });

Here When you adding foreign key, by default it will have a Null value.This 'null referencing' may cause the issue. Using nullable() foreign key will avoid that issue.

Answer 2

See the docs here

You need to install doctraine/dbal before modifying a column, be sure to add the doctrine/dbal dependency to your composer.json file. The Doctrine DBAL library is used to determine the current state of the column and create the SQL queries needed to make the specified adjustments to the column and the you should try what I found on this SO post

Schema::table('posts', function (Blueprint $table) {
    $table->integer('user_id')->unsigned()->change();

    $table->foreign('user_id')->references('id')->on('users');
}); 

change() method for change structure of column

after this run the artisan command

php artisan migrate

if this doesn't work for you shoot the comment here! :)