use jsonb column

database/migrations/2018_07_08_193640_create_data_rows_table.php

@@ -16,7 +16,7 @@ class CreateDataRowsTable extends Migration
         Schema::create('data_rows', function (Blueprint $table) {
             $table->increments('id');
             $table->unsignedInteger('data_table_id')->index();
-            $table->longtext('data');
+            $table->jsonb('data');
 
             $table->foreign('data_table_id')->references('id')->on('data_tables')
                 ->onDelete('cascade');