ManualBindings

A simple example that illustrates establishing bindings programmatically, including a number of options such as validation and an array operator, and indexed accessor methods. A custom model object implements custom validation method.

Originally from “Cocoa Bindings Examples and Hints”, converted to PyObjC by u.fiedler.

Sources

AppController.py

#
#  AppController.py
#  ManualBindings
#
from Cocoa import *

class AppController (NSObject):
    arrayController = objc.IBOutlet()
    selectedNameField = objc.IBOutlet()
    selectedPriceField = objc.IBOutlet()
    tableView = objc.IBOutlet()
    totalCountField = objc.IBOutlet()

    def awakeFromNib(self):
        self.totalCountField.bind_toObject_withKeyPath_options_(u"value", self.arrayController, u"arrangedObjects.@sum.price", None)
        bindingOptions = {}
        bindingOptions[u'NSNullPlaceholder'] = u"No Name"
        self.selectedNameField.bind_toObject_withKeyPath_options_(u"value", self.arrayController, u"selection.name", bindingOptions)
        # binding for "name" column
        tableColumn = self.tableView.tableColumnWithIdentifier_(u'name')
        tableColumn.bind_toObject_withKeyPath_options_(u"value", self.arrayController, u"arrangedObjects.name", bindingOptions)

        # binding options for "price"
        del bindingOptions[u'NSNullPlaceholder']
        bindingOptions[NSValidatesImmediatelyBindingOption] = True

        # binding for selected "price" field
        self.selectedPriceField.bind_toObject_withKeyPath_options_(u"value", self.arrayController, u"selection.price", bindingOptions)

        #binding for "price" column
        tableColumn = self.tableView.tableColumnWithIdentifier_(u'price')
        tableColumn.bind_toObject_withKeyPath_options_(u"value", self.arrayController, u"arrangedObjects.price", bindingOptions)

        # bind array controller to self's itemsArray
        # we use _k_itemsArray because Python does not have a separate
        # namespace for instance variables, and we are using accessors.
        self._k_itemsArray = []
        self.arrayController.bind_toObject_withKeyPath_options_(u"contentArray", self, u"self.itemsArray", None)

    @objc.accessor
    def countOfItemsArray(self):
        return len(self._k_itemsArray)

    @objc.accessor
    def objectInItemsArrayAtIndex_(self, index):
        return self._k_itemsArray[index]

    @objc.accessor
    def insertObject_inItemsArrayAtIndex_(self, obj, idx):
        self._k_itemsArray.insert(idx, obj)

    @objc.accessor
    def removeObjectFromItemsArrayAtIndex_(self, idx):
        del self._k_itemsArray[idx]

    @objc.accessor
    def replaceObjectInItemsArrayAtIndex_withObject_(self, idx, obj):
        self._k_itemsArray[idx] = obj

ITEM_ERROR_DOMAIN = u'ITEM_ERROR_DOMAIN'
ITEM_NEGATIVE_PRICE = 10001

class Item(NSObject):
    def price(self):
        return getattr(self, '_k_price', 0.0)

    def setPrice_(self, aPrice):
        self._k_price = aPrice

    def name(self):
        return getattr(self, '_k_name', None)

    def setName_(self, aName):
        self._k_name = aName

    @objc.accessor
    def validatePrice_error_(self, value, error):
        if value >= 0:
            return True, value, None

        errorString = u'Price cannot be negative'
        userInfoDict = {NSLocalizedDescriptionKey: errorString}
        error = NSError.alloc().initWithDomain_code_userInfo_(
            ITEM_ERROR_DOMAIN,
            ITEM_NEGATIVE_PRICE,
            userInfoDict)

        return False, value, error

ManualBindings.py

from PyObjCTools import AppHelper

# import classes required to start application
import AppController

# start the event loop
AppHelper.runEventLoop()

setup.py

"""
Script for building the example:

Usage:
    python setup.py py2app
"""
from distutils.core import setup
import py2app

setup(
    name="ManualBindings",
    app=["ManualBindings.py"],
    data_files=["English.lproj"],
)

Resources

• Download example