无法迁移外键

Question

Here is Vehicles migrate :

public function up()
    {
        Schema::create('Vehicles', function (Blueprint $table) {
            $table->increments('serie');
            $table->string('color');
            $table->integer('power');
            $table->float('capacity');
            $table->float('speed');
            $table->integer('maker_id')->unsigned();
            $table->timestamps();
        });

        Schema::table('Vehicles', function (Blueprint $table){
            $table->foreign('maker_id')->references('id')->on('Makers');
        });
    }

Here is Makers Migrate :

public function up()
    {
        Schema::create('Makers', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->integer('phone');
            $table->timestamps();
        });
    }

When I run artisan migrate , I got following error messages.

 [Illuminate\Database\QueryException]
 SQLSTATE[HY000]: General error: 1005 Can't create table `api`.`#sql-14b0_71
 ` (errno: 150 "Foreign key constraint is incorrectly formed") (SQL: alter t
 able `Vehicles` add constraint `vehicles_maker_id_foreign` foreign key (`ma
 ker_id`) references `Makers` (`id`))



 [PDOException]
 SQLSTATE[HY000]: General error: 1005 Can't create table `api`.`#sql-14b0_71
 ` (errno: 150 "Foreign key constraint is incorrectly formed")

I want to create two tables: Vehicles & Makers . In vehicles , maker_id is foreign key . I read the some references for laravel migration from various sources. But I can't find solution.

Answer 1

Pay attention to your migration files order, you have two solutions:

1. Change order: make Makers Migrate file first then Vehicles Migrate .

2. If Makers Migrate file comes after Vehicles Migrate file and you don't want to change order, move this:

    Schema::table('Vehicles', function (Blueprint $table){ $table->foreign('maker_id')->references('id')->on('Makers'); }); 

   To Makers Migrate file.

Answer 2

Now I delete makers migrate file and I run vehicles migrate file . Below is vehicles migrate file.

public function up()
    {
        Schema::create('Vehicles', function (Blueprint $table) {
            $table->increments('serie');
            $table->string('color');
            $table->integer('power');
            $table->float('capacity');
            $table->float('speed');
            $table->integer('maker_id')->unsigned();
            $table->timestamps();
        });
    }

But I got the below errors

PHP Fatal error:  Cannot redeclare class CreateVehicleTable in C:\xampp\htdocs\m
yownapi\database\migrations\2016_07_05_190215_vehicles_table.php on line 35


  [Symfony\Component\Debug\Exception\FatalErrorException]
  Cannot redeclare class CreateVehicleTable

Answer 3

Now it is work properly with below codes

Makers Migrate

<?php

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

class MakersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('Makers', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->integer('phone');
            $table->timestamps();
        });

        Schema::table('Vehicles', function(Blueprint $table){
            $table->foreign('maker_id')->references('id')->on('makers');
        });
    }

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

Vehicles Migrate

<?php

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

class VehiclesTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('Vehicles', function (Blueprint $table) {
            $table->increments('serie');
            $table->string('color');
            $table->float('power');
            $table->float('capacity');
            $table->integer('maker_id')->unsigned();
            $table->timestamps();
        });
    }

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

Answer 4

There is a simple way to do this. From your Vehicles migration, make the following changes

public function up()
{
    Schema::create('Vehicles', function (Blueprint $table) {
        $table->increments('serie');
        $table->string('color');
        $table->integer('power');
        $table->float('capacity');
        $table->float('speed');
        $table->integer('maker_id')
        $table->foreign('maker_id')
              ->references('id')->on('Makers');
        $table->timestamps();
    });
}

And since you will be adding the values form the id column in Makers , Laravel already has got your back, so there is really no need to add the unsigned() property there. Its still Okay if you add it there.

Hope I have answered your question. For More Details