schema builder laravel migrations unique on two columns

问题

How can I set a unique constraints on two columns?

class MyModel extends Migration {
  public function up()
  {
    Schema::create('storage_trackers', function(Blueprint $table) {
      $table->increments('id');
      $table->string('mytext');
      $table->unsignedInteger('user_id');
      $table->engine = 'InnoDB';
      $table->unique('mytext', 'user_id');
    });
  }
}

MyMode::create(array('mytext' => 'test', 'user_id' => 1);
// this fails??
MyMode::create(array('mytext' => 'test', 'user_id' => 2);

回答1:

The second param is to manually set the name of the unique index. Use an array as the first param to create a unique key across multiple columns.

$table->unique(array('mytext', 'user_id'));

or (a little neater)

$table->unique(['mytext', 'user_id']);

回答2:

Simply you can use

$table->primary(['first', 'second']);

Reference: http://laravel.com/docs/master/migrations#creating-indexes

As an example:

    Schema::create('posts_tags', function (Blueprint $table) {

        $table->integer('post_id')->unsigned();
        $table->integer('tag_id')->unsigned();

        $table->foreign('post_id')->references('id')->on('posts');
        $table->foreign('tag_id')->references('id')->on('tags');

        $table->timestamps();
        $table->softDeletes();

        $table->primary(['post_id', 'tag_id']);
    });

来源：https://stackoverflow.com/questions/20065697/schema-builder-laravel-migrations-unique-on-two-columns