Laravel数据迁移

Question

有没有办法在Laravel中进行数据迁移？我已经找到了一些关于如何为数据库设定种子的说明,但它没有涉及我需要将一个字段拆分成多个字段,或者将多个字段合并为一个字段的情况.

一种可能的解决方案是查询数据库并更新循环上的每条记录.这种方法的问题是模型在迁移期间可能无法反映表模式(Django为此提供了解决方案).

Answer 1

Laravel内置了迁移:http://laravel.com/docs/migrations

简单地跑

php artisan make:migration migration_name_here

它将在app/database/migrations下创建一个迁移.然后,您可以在up()和down()方法中使用Laravel的数据库类.

我们以此为例......

class SplitColumn extends Migration {

    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('table_name', function($table)
        {
            // Create new columns for table_name (1 column split into 2).
            $table->string('new_column');
            $table->string('new_column_b');
        });

        // Get records from old column.
        $results = DB::table('table_name')->select('old_column')->get();

        // Loop through the results of the old column, split the values.
        // For example, let's say you have to explode a |.
        foreach($results as $result)
        {
            $split_value = explode("|", $result->old_column);

            // Insert the split values into new columns.
            DB::table('table_name')->insert([
                "new_column"    =>  $split_value[0],
                "new_column_b"  =>  $split_value[1]
            ]);
        }

        // Delete old column.
        Schema::table('table_name', function($table)
        {
            $table->dropColumn('old_column');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('table_name', function($table)
        {
            // Re-create the old column.
            $table->string('old_column');
        });

        // Get records from old column.
        $results = DB::table('table_name')->select('new_column', 'new_column_b')->get();

        // Loop through the results of the new columns and merge them.
        foreach($results as $result)
        {
            $merged_value = implode("|", [$result->new_column, $result->new_column_b]);

            // Insert the split values into re-made old column.
            DB::table('table_name')->insert([
                "old_column"    =>  $merged_value
            ]);
        }

        // Delete new columns.
        Schema::table('table_name', function($table)
        {
            $table->dropColumn('new_column');
            $table->dropColumn('new_column_b');
        });
    }
}