Play Framework How can i pass collection to action create()? - collections

Question

I am starter with Play Framework. I got a problem when i passed parameters.
I want to pass a collection from view to controller. And i do not know how to do this. I always get "null" when i get a collection from view.
My code below:
Code in controller:
public static void create(List<Book> books) throws Exception {
for(Book book : books){
System.out.println(book.get(0).author) // i got null :(
}
}
Code in HTML
Book 1:
<input type="text" name="books.author" />
<input type="text" name="books.title" />
Book 2:
<input type="text" name="books.author" />
<input type="text" name="books.title" />
When i submit, i want to add 2 records into database include Book1 and Book2. Please support me
Thanks

Answer 1

You can make this work by simplying add the array indicator to your HTML code
Book 1:
<input type="text" name="books[0].author" />
<input type="text" name="books[0].title" />
Book 2:
<input type="text" name="books[1].author" />
<input type="text" name="books[1].title" />
I have tested this solution, and it works fine.
Also note that your println will not compile, as you are calling get(0) on the Book object, and not the List object. If you just println book.author, it outputs the author as required.

Answer 2

In case anyone needs an example of the Javascript for dyanmically adding and removing books (JQUERY needed):
<script type="text/javascript">
$(document).ready(function() {
var bookCount=0;
$('#btnAddBook').click(function() {
bookCount++;
//newElem = go up a to the parent div then grab the previous container
var newElem = $(this).parent().prev().clone().attr('id', 'book[' + bookCount + ']');
//for each input inside the div, change the index to the latest bookCount
$(newElem).find("input").each(function(){
var name = $(this).attr('name');
var leftBracket = name.indexOf("[");
var rightBracket = name.indexOf("]");
var beforeBracketString = name.substring(0,leftBracket+1);//+1 to include the bracket
var afterBracketString = name.substring(rightBracket);
$(this).attr('name', beforeBracketString + bookCount + afterBracketString);
});
//insert it at the end of the books
$(this).parent().prev().after(newElem);
$(newElem).find("input").each(function(){
$(this).attr('id', $(this).attr('id') + bookCount);
});
//enable the remove button
$('#btnRemovebook').removeAttr('disabled');
//If we are at 16 divs, disable the add button
if (bookCount == 15)
$(this).attr('disabled','disabled');
});
$('#btnRemoveBook').click(function() {
bookCount--;
//remove the last book div
$(this).parent().prev().remove();
//in case add was disabled, enable it
$('#btnAddbook').removeAttr('disabled');
//never let them remove the last book div
if (bookCount == 0)
$(this).attr('disabled','disabled');
});
});
</script>
<!-- HTML Snippet -->
<div id="book[0]">
<label> Book: </label>
<input type="text" name="books[0].author" value="Author" />
<input type="text" name="books[0].title" value="Title" />
</div>
<div>
<input type="button" id="btnAddbook" value="Add another book" />
<input type="button" id="btnRemovebook" value="Remove last book" disabled="disabled" />
</div>
<!-- REST of the HTML -->