Hk-tang

[query.getSingleResult()](https://docs.oracle.com/javaee/7/api/javax/persistence/Query.html#getSingleResult--) causes an exception could be thrown if there is not exactly one row returned. Although this commit does not implement logic on how to decide which result in the...

`$temp_file[0]` would make it more concise

The jQuery doc for [jQuery.data()](https://api.jquery.com/jQuery.data/) says this is a "low-level method" and that you should use .data() instead.