skip CSV columns that don't exist in the database

If no mapping is found, first row is used, but csv columns not found in
the DB are stripped out to prevent insert errors.
This is done only once, up at the top, and is only done if no mapping
is specified.

Author: jackfruh

src/Flynsarmy/CsvSeeder/CsvSeeder.php

@@ -5,6 +5,7 @@
 use DB;
 use Hash;
 use Illuminate\Database\Seeder;
+use Illuminate\Database\Schema;
 
 /**
  * Taken from http://laravelsnippets.com/snippets/seeding-database-with-csv-files-cleanly
@@ -160,6 +161,13 @@ public function seedFromCSV($filename, $deliminator = ",")
             {
                 $mapping = $row;
                 $mapping[0] = $this->stripUtf8Bom($mapping[0]);
+
+                // skip csv columns that don't exist in the database
+                foreach($mapping  as $index => $fieldname){
+                    if (!DB::getSchemaBuilder()->hasColumn($this->table, $fieldname)){
+                       array_pull($mapping, $index);
+                    }
+                }
             }
             else
             {