Why is なんだって at the end of 「当日券は現金購入だけなんだって。」?


Consider

> 当日券は現金購入だけなんだって。
>
> They say same-day tickets are available for cash purchase only.

(Source: from a Tofugu [tutorial on だけ](https://www.tofugu.com/japanese-
grammar/dake/))

**Questions:**

  1. Is 現金購入 one word, or two placed next to each other appositionally? (Or maybe there's a の in between them that's being dropped?)

  2. What is なんだって doing at the end of this sentence? I assume it's short for 何 + だ + 言って? If so, why put 言う in the て form at the end of the sentence (since this doesn't seem like it's a command)? Also what role is 何 playing here (given that this doesn't look like an interrogative sentence)?



  1. 現金購入 is not an appositive construction. 'Cash' is not equal to 'purchase', right? 購入 ("～ purchase") is one of those words that can form compounds almost like a suffix (e.g., クレカ購入, 電子マネー購入, 定期購入). See the last part of [this answer](https://japanese.stackexchange.com/a/19379/5010).
  2. It's なんだ + って. See Chocolate's links. 
    * なんだ (なのだ) is a plain example of [explanatory-の](https://www.wasabi-jpn.com/japanese-grammar/explanatory-noda/).
    * って is a quotative particle that means "I heard" here.



  1. 現金購入 is not an appositive construction. 'Cash' is not equal to 'purchase', right? 購入 ("～ purchase") is one of those words that can form compounds almost like a suffix (e.g., クレカ購入, 電子マネー購入, 定期購入). See the last part of [this answer](https://japanese.stackexchange.com/a/19379/5010).
  2. It's なんだ + って. See Chocolate's links. 
    * なんだ (なのだ) is a plain example of [explanatory-の](https://www.wasabi-jpn.com/japanese-grammar/explanatory-noda/).
    * って is a quotative particle that means "I heard" here.

