javascript - Using Knockout and Breeze with Cascading Dropdowns -


so i've been @ , forth quite long time now, i'll point.

i creating application based on hottowel template, i'm using knockout, breeze, q etc. i'm using breeze query data server, , load data first select (as options). changes selectedmodel observable , subscription triggers ( subscription current "solution", have used data-bind etc same results). subscription takes new selectedmodel value , uses data second observable. query passes , results stored in modelproperties observable array, yet ui not update second select (it's empty). strange thing is, pressing ctrl + f5 (i tried 50 times in row) populates correctly, never on first load.

tldr; 2 selects, selected option of first 1 defines query options of second one. queries work, observables populated, first select populated, second never on first boot on following ctrl+f5.

here snippets regarding piece of application: viewmodel:

define(['services/logger', 'services/datacontext'], function (logger, datacontext) {     var models = ko.observablearray();     var modelproperties = ko.observablearray();     var selectedmodel = ko.observable();     var init = true;      function activate() {         logger.log('search view activated', null, 'search', true);         return datacontext.getmodels(models);     }      var sub = selectedmodel.subscribe(function (newvalue) {         return datacontext.getmodelproperties(modelproperties, newvalue);     });      var vm = {         activate: activate,         models: models,         selectedmodel: selectedmodel,         modelproperties: modelproperties,         title: 'search view'     };      return vm;

the view's code:

<!doctype html> <html xmlns="http://www.w3.org/1999/xhtml"> <head>     <title></title> </head> <body id="one">     <select id="entityselect" class ="entityselect" name="first"         data-bind="options: models, value: selectedmodel">     </select>     <select id="propertyselect" class ="propertyselect" data-bind=     'options:modelproperties'></select> </body> </html>

and methods in datacontext:

        var getmodels = function (modelsobservable) {         var query = entityquery.from('models');         return manager.executequery(query)             .then(querysucceeded)             .fail(queryfailed);          function querysucceeded(data) {             logger.log("query succeeded", true);             logger.log(data);             if (modelsobservable) {                 modelsobservable(data.results);             }             logger.log('retrieved [models] remote data source',                 data, true);         }         function queryfailed(data) {             logger.log(data.tostring(), data, true);         }     };      var getmodelproperties = function (propertiesobservable,modelname) {         var query = entityquery.from('modelproperties').withparameters({ name: modelname });         return manager.executequery(query)             .then(querysucceeded)             .fail(queryfailed);          function querysucceeded(data) {             logger.log("query succeeded", null, true);             logger.log(data);             if (propertiesobservable) {                 propertiesobservable(data.results);             }             logger.log('retrieved [properties] remote data source',                 data, true);         }         function queryfailed(data) {             logger.log(data.tostring(), data, true);         }     };

once again i'd point out queries pass, , observablearrays populated results (checked .peek() ).

here screenshots clarify problem: on first boot vs : http://i.imgur.com/8gd53yh.png

then, ctrl+f5 http://i.imgur.com/vzo8d70.png

i have tried pretty can think of, , googled came mind, no avail. appreciated! also, first post here apologize mistakes!

here few comments -

your view makes no sense. if using hottowel template there lot of mark-up not needed there, considering using durandal.js composition , additional mark-up hurting you.

if indeed loading 'subview' more or less should - 

<select id="entityselect" class ="entityselect" name="first" data-bind="options: models, value: selectedmodel"></select> <select id="propertyselect" class ="propertyselect" data-bind='options:modelproperties'></select>

next, if using cascading dropdowns have mentioned method before , suggest everyone. make second dependent on first ko.computed.

var models = ko.observablearray(); var modelproperties = ko.computed(function () {     var modelarr = ko.observablearray();     if (!selectedmodel()) { return modelarr; }     datacontext.getmodelproperties(modelarr, selectedmodel().then(function() { return modelarr(); }); });

now modelproperties null until select model, go out , properties of model.

it's important understand difference between function declarations using. var myfunc = function () {}; constructor function , evaluate on view model instantiation. function myfunc () {} standard function , wait until called before evaluating.


-

Comments

Post a Comment

Popular posts from this blog

scala - 'wrong top statement declaration' when using slick in IntelliJ -

Image
i'm porting project scala 2.9 2.10, therefore have use slick instead of scalaquery. i'm using slick 2.1.0 since supports ms access. according this tutorial , upgrade guide changed robs object class , added val robs : why error message wrong top statement declaration , how rid of it? edit: i'm new scala... according this question seems can't put val outside of methods or classes, right? code above directly in packge. right approach slick then? should move code in class or trait? according this changed val robs = tablequery[robs] to object robs extends tablequery(new robs(_)) {} . no warnings or errors anymore. :)
Read more

c# - DevExpress.Wpf.Grid.InfiniteGridSizeException was unhandled -

Image
when using devexpress, see error: devexpress.wpf.grid.infinitegridsizeexception unhandled message="by default, infinite grid height not allowed since grid rows rendered , hence grid work slowly. fix issue, should place grid container give finite height grid, or should manually specify grid's height or maxheight. note can avoid exception setting gridcontrol.allowinfinitegridsize static property true, in case grid run slowly." the problem dxgrid has infinite height. to fix, set height non-infinite. snoop absolutely invaluable this: if "height" xaml element infinite (i.e. 0 or nan ), can set using one of following: option 1: height="{binding path=actualheight, relativesource={relativesource mode=findancestor, ancestortype=uielement}}" option 2: verticalalignment="stretch" option 3: height="auto" hint: use verticalalignment="stretch" if child of grid <rowdefinition height=
Read more

PySide and Qt Properties: Connecting signals from Python to QML -

i trying run simple pyside appliccation design made in qml. call function in qml python in separated thread. i have following qml view: import qt 4.7 rectangle { visible: true width: 100; height: 100 color: "lightgrey" text { id: datestr objectname: "datestr" x: 10 y: 10 text: "init text" font.pixelsize: 12 function updatedata(text) { datestr.text = qstr(text) console.log("you said: " + text) } } } here application: some imports.... #!/usr/bin/python import sys import time pyside import qtdeclarative, qtcore pyside.qtgui import qapplication pyside.qtdeclarative import qdeclarativeview the qthread worker.... #worker thread class worker(qtcore.qthread): updateprogress = qtcore.signal(int) def __init__(self, child): qtcore.qthread.__init__(self) self.child = child def run(self):
Read more