source: Dev/trunk/src/client/dojox/mvc/tests/1.7/models/LoanWizardModel.js

define([
        "dojo/_base/declare",
        "dojox/mvc",
        "dojox/mvc/StatefulModel",
        "dojo/data/ItemFileWriteStore"
], function(declare, mvc, StatefulModel, ItemFileWriteStore){

        return declare("dojox.mvc.tests.models.LoanWizardModel", [StatefulModel], {

                // data store for pie chart
                chartStore: new ItemFileWriteStore({ data: {
                        "hierarchical" : false,
                        "identifier"   : "id",
                        "items" : [
                                   { "id" : "mortgage", "x"  : 1, "y"   : 0 },
                                   { "id" : "taxes", "x"  : 2, "y"       : 0 },
                                   { "id" : "otherhousing", "x"  : 3, "y"       : 0 }
                                   ]
                }}),

                constructor: function (args) {
                        // try to precompute address fields from the zipcode and country...      
                        mvc.bindInputs([this.Zip, this.Country], dojo.hitch(this, this._lookupAddrs));
                        // simple dependence of percentages on input values and total
                        mvc.bindInputs([this.Mortgage, this.Taxes, this.OtherHousing, this.BaseIncome, this.BonusIncome], dojo.hitch(this, this._recomputeTotalAndPercentages));

                        mvc.bind(this.HousingPercent, "value", this.HousingPercent, "valid", dojo.hitch(this, this._isHousingLessThanOrEqualToThirtyThreePercent), true);

                        mvc.bind(this.HousingPercent, "value", this.HousingPercent, "relevant", dojo.hitch(this, this._nonZeroRelevance), true);
                        mvc.bind(this.TotalHousing, "value", this.TotalHousing, "relevant", dojo.hitch(this, this._nonZeroRelevance), true);

                        this._recomputeTotalAndPercentages();  // get things going first time...
                },

                _lookupItem: function( dataSource, identity ) {
                        var found_item;
                        dataSource.fetchItemByIdentity( { "identity": identity, 
                                "onItem": function (item) { found_item = item; } } );
                        return found_item;
                },

                _lookupAddrs: function() {
                        if ( this.Zip.get("value") == null || isNaN(this.Zip.get("value"))) return;
                        var pThis = this;
                        var query = { "postalcode": this.Zip.get("value"), "country": this.Country.get("value") };              
                        var xhrArgs = {
                                        url: "zips/"+this.Zip.get("value")+".json",
                                        sync: true,
                                        content: query,
                                        preventCache: true,
                                        handleAs: "json",
                                        load: function(data, io) {
                                                pThis.City.set("value", data.postalcodes[0].placeName );
                                                pThis.County.set("value", data.postalcodes[0].adminName2 );
                                                pThis.State.set("value", data.postalcodes[0].adminCode1 );
                                                pThis.Zip.set("valid", true ); 
                                        },
                                        error: function (data) {
                                                // we couldn't find this country/zip combination...clear the fields and set validity=false
                                                pThis.City.set("value", "" );
                                                pThis.County.set("value", "" );
                                                pThis.State.set("value", "" );
                                                pThis.Zip.set("valid", false );
                                        }
                        };
                        //Call the synchronous xhrGet
                        var deferred = dojo.xhrGet(xhrArgs);    
                },

                _recomputeTotalAndPercentages: function() {
                        var mortgage = parseInt(this.Mortgage.get("value"));
                        var taxes = parseInt(this.Taxes.get("value"));
                        var otherHousing = parseInt(this.OtherHousing.get("value"));
                        var totalHousing = mortgage + taxes + otherHousing;

                        var baseIncome = parseInt(this.BaseIncome.get("value"));
                        var bonusIncome = parseInt(this.BonusIncome.get("value"));
                        var totalIncome = baseIncome + bonusIncome;

                        var housingPercentage = Math.round(totalHousing / totalIncome * 100);

                        this.HousingPercent.set("value", housingPercentage);
                        this.TotalHousing.set("value", totalHousing);
                        this.TotalIncome.set("value", totalIncome);

                        // map the values into the data source structure required for chart display as well...
                        var mortgageItem = this._lookupItem(this.chartStore, "mortgage");
                        var taxesItem = this._lookupItem(this.chartStore, "taxes");
                        var otherItem = this._lookupItem(this.chartStore, "otherhousing");
                        this.chartStore.setValue(mortgageItem, "y", mortgage);
                        this.chartStore.setValue(taxesItem, "y", taxes);
                        this.chartStore.setValue(otherItem, "y", otherHousing);
                },

                _isHousingLessThanOrEqualToThirtyThreePercent: function(newValue) {
                        return newValue <= 33;
                },

                _nonZeroRelevance: function(newValue) {
                        if ( newValue > 0 ) return true;
                        else return false;
                }

        });
});