How to update Alloy collection row?

Hi, I've been working with Alloy collections for a couple of days.

In short: I cannot do that simple thing: retrieve a collection row, change the content, and save it back.

In detail: I have got my binding working beautifully in my 'History table' as follows:

historyList.js

var books = Alloy.Collections.book;
books.fetch();

historyList.xml

<Alloy>
<Collection src="book" />
<Window id="winHistoryList" class="container">
    <TableView id="tableview" dataCollection="book">
      <SearchBar id="searchBar" hintText="search"></SearchBar>
      <TableViewRow id="row" dataId="{book_id}" dataTitle="{sec1_1_title}">
        <Label class="rowName" text="{sec1_1_title}"></Label>
        <Label class="rowDate" text="{sec1_1_date_book}"></Label>
    </TableViewRow> 
    </TableView>
</Window>
</Alloy>

Elsewhere in the app, I add instances to the collection, all going well too:

var books = Alloy.Collections.book;
    var data = {
       "incidate": indicate,
       "sec1_1_date_book":todaysDate,
       "sec1_1_title": title
    };
    var book = Alloy.createModel("book", data);
    books.add(book);
    // Save our model to the SQL database
    book.save(book);

So that you really have all the elements, here is my model declaration:

exports.definition = {
    config: {
        "columns": {
            "book_id": "INTEGER PRIMARY KEY AUTOINCREMENT",
            "incidate": "TEXT",
            "sec1_1_division": "TEXT",
            "sec1_1_site": "TEXT",
            "sec1_1_location": "TEXT",
            "sec1_1_date_book": "TEXT",
            [...]
 
        },
        "adapter": {
            "type": "sql",
            "collection_name": "books",
            "idAttribute": "book_id"
        }
    },
 
    extendModel: function(Model) {      
        _.extend(Model.prototype, {
            // Extend, override or implement the Backbone.Model methods                     
        });
        return Model;
    },
 
    extendCollection: function(Collection) {        
        _.extend(Collection.prototype, {
 
            // Implement the comparator method.
            comparator : function(book) {
                return book.get('book_id');
            }
 
        }); // end extend
 
        return Collection;
    }
}

We're getting to the point. In another location I have a form with one field per model column:

section1.xml

<Alloy>
    <Collection src="book" />
    <Window id="winSection1">
        <View class="formRow">
            <Label class="formLabel">Division</Label>
            <TextArea class="textArea250" id="sec1_1_division" />
        </View> 
 
        <View class="formRow">
            <Label class="formLabel">Site / Project</Label>
            <TextArea class="textArea250" id="sec1_1_site"/>
        </View> 
        [...]

I set the column values like this:

section1.js

var args = arguments[0] || {};
if (args.data){
    $.sec1_1_division.value = args.data.sec1_1_division || '';
    $.sec1_1_site.value = args.data.sec1_1_site || ''; 
    $.sec1_1_location.value = args.data.sec1_1_location || '';

and in the same file set my onclick save action:

$.finishButton.addEventListener('click',function(e){
    var books = Alloy.Collections.book;
 
    var data = {
       "incidate": incidate,
       "sec1_1_division": $.sec1_1_division.value,
       "sec1_1_site": $.sec1_1_site.value,
       "sec1_1_location": $.sec1_1_location.value,
    [...]

Finally I use my custom ID to try and fetch the collection row, update it and spit it back. That's where I'm stuck as.

var books = Alloy.Collections.book;
var book = books.fetch({"book_id":args.data.book_id}); // not working, it retrieves all of them
book.save(data);

Can anyone enlighten me here? How do you update a Collection row???