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Presenter responsible for wiring together the top-level View (a ContactsPage)
and the top-level model (a Contacts collection).
For convenience, we derive this presenter from Backbone's View class to pick
up some benefits like automatic references to the model and the View's
top-level DOM element. The real View role, however, is filled by the QuickUI
Backbone defines a $el member for us, which is designed to hold a jQuery
instance. Since a QuickUI control *is* a jQuery reference, we can use the $el
member to directly hold a reference to the QuickUI control serving as the View.
class window.ContactsPresenter extends Backbone.View
# A new contact has been added.
add: ( contact, contacts, options ) ->
.insertItemBefore( contact, options.index ) # Add contact to the list.
.selectedIndex( options.index ) # Select the card for the new contact.
# The contact's name has changed. We resort the card in response. We could
# easily accomplish this by invoking the collection's own sort() method,
# but that will cause a complete reset of the collecction, and therefore a
# complete (and slow) repopulation of the list box. Instead, we remove the
# card from the collection, then reinsert it at the correct position.
change: ( contact ) ->
@model.remove contact
index = findInsertLocation contact, @contacts(), @model.comparator
@model.add contact, options: at: index
@$el.selectedIndex index # Keep the contact selected.
# Shorthand for referring to the set of contacts
contacts: -> @model.models
# Erase all contacts.
# REVIEW: Is there a better way to do this in Backbone?
eraseAll: ->
contacts = @contacts()
while contacts.length > 0
contacts[0].destroy silent: true
# The View events we're interested in.
eraseAll: "eraseAll"
new: "newContact"
samples: "samples"
initialize: ->
@model.on "add", @add, this
@model.on "change:name", @change, this
@model.on "reset", @render, this
@model.on "remove", @remove, this
# The View has raised a new event.
newContact: ->
# Create a new contact with an empty name.
# (The empty name will sort the new contact to the beginning of the list.)
@model.add name: ""
# Put the card for the new contact in editing mode.
@$el.selectedContact()?.editing true
# Render all the contacts.
render: -> @$el.contacts @contacts()
# Remove the indicated contact.
remove: ( contact, contacts, options ) ->
@$el.selectedContact().editing false
@$el.removeItemAt options.index
# Select the new item at the previous position, or the last item.
@$el.selectedIndex Math.max options.index, @contacts.length
# Replace set of contacts with sample contact set.
# REVIEW: Is there a better way to do this in Backbone?
samples: ->
$.getJSON( "contacts.json" ).success ( data ) =>
@model.reset data.contacts for contact in @contacts()
# Return the index of the location where the given model should be inserted
# in order to preserve sort order. Note that this function is defined with
# "=" instead of ":", making the function private to the class scope.
findInsertLocation = ( model, models, comparator ) ->
min = 0
max = models.length - 1
key = comparator model
# A simple binary search
while max >= min
mid = Math.floor ( min + max ) / 2
considerKey = comparator models[ mid ]
if considerKey < key
min = mid + 1
else if considerKey > key
max = mid - 1
return mid # Position of an existing model with the same key
return max + 1 # Where the model would be if it were already in the list