Multiple JavaScript-ViewModels on SinglePage-Site, Variable-Naming-Conflict - javascript

I am working on a single-page-application. For this purpose, I am using Knockout.js, which is really great for this task.
Now I'm facing a problem: The content of the pages is appended with jQuerys append-function. When i append two detail-pages from the same template, i have a conflict with my viewmodel-object-names, since both declare it's offlineDemoDetailViewModel-variable under use of the same name.
TestDetailA (from TestDetail Template): offlineDemoDetailViewModel = offlineDemoDetailViewModel();
TestDetailB (from TestDetail Template): offlineDemoDetailViewModel = offlineDemoDetailViewModel();
What is the best way to handle this? Should i create the variable-name dynaically or is there a better way?
Thanks a lot!
Just for Info, here is my (test) offlineDemoDetailViewModel-code:
var offlineDemoDetailViewModel = function () {
var _viewmodel = new (function() {
this.uuid = ko.observable(localDatabase.createUUID());
});
return _viewmodel;
};

Related

Using idb instead of localStorage

I'm following the Progressive Web App lab from Google and it says that it's using localStorage for simplicity but that we should change it to idb.
Basically, we want to store a list of cities to display their weather information.
I tried using plain idb following the info here but I think I'm too new to this and I couldn't get any of this. Am I supposed to do:
const dbPromise = idb.open('keyval-store', 1, upgradeDB => {
upgradeDB.createObjectStore('keyval');
});
and would keyval be the name of my variable where I would use keyval.get() or keyval.set() to get and store values?
I decided to move on to the simpler idbKeyval, I'm doing:
app.saveSelectedCities = function() {
var selectedCities = JSON.stringify(app.selectedCities);
idbKeyval.set(selectedCities);
};
instead of the localStorage example:
app.saveSelectedCities = function() {
var selectedCities = JSON.stringify(app.selectedCities);
localStorage.selectedCities = selectedCities;
};
and
app.selectedCities = idbKeyval.keys().then(keys => console.log(keys)).catch(err => console.log('It failed!', err));
instead of the localStorage example:
app.selectedCities = localStorage.selectedCities;
But my app is not loading any data, and in the developer tools console, I get:
app.js:314 Uncaught ReferenceError: idbKeyval is not defined(…)
I'm sure I'm missing something trivial but these are my first steps with javascript and the likes, so please, any help with any of the points touched here would be greatly appreciated!
Given the error you're seeing, it looks like you've forgotten to include the idb-keyval library.
I too was going through this, and wanted it to work with localForage. Took a bit, because I'm new to it too, but here is what I used for the save and load functions which made it all work.
// TODO add saveSelectedCities function here
// Save list of cities to localStorage
app.saveSelectedCities = function() {
var selectedCities = JSON.stringify(app.selectedCities);
localforage.setItem('selectedCities', selectedCities);
//localStorage.selectedCities = selectedCities;
}
localforage.getItem('selectedCities').then(function(cityList) {
app.selectedCities = cityList;
app.selectedCities.forEach(function(city) {
app.getForecast(city.key, city.label);
});
}).catch(function(err) {
app.updateForecastCard(initialWeatherForecast);
app.selectedCities = [
{key: initialWeatherForecast.key, label: initialWeatherForecast.label}
];
app.saveSelectedCities();
});

Problems when testing (whilst using javascript & QUnit)

Given the following code, I have managed to write a test by making use of QUnit for the first part but was unable to test finder.doRoutefinding. How can I 'mock'the function finder.doRoutefinding? (Mockjax cannot be used here since no ajax calls are involved)
`finder.doSelectDestination = function(address)
{
finder.destination = address;
finder.doRoutefinding(
finder.departure,
finder.destination,
finder.whenRouteLoaded,
finder.showRoute);
}
test('Destination Selector',
function()
{
address="London";
finder.doSelectDestination(address);
equal(pathfinder.destination,address, "Succesful Destination Selection");
}
);
There are caveats, but you could simply replace the function with your mock:
var originalDoRoutefinding = finder.doRoutefinding;
finder.doRoutefinding = function() {
// Mock code here.
};
// Test code here.
finder.doRoutefinding = originalDoRoutefinding;
If that kind of thing works for you, you might consider using a library like Sinon.JS.

Breeze Partial initializer

I have a Single Page Application that is working pretty well so far but I have run into an issue I am unable to figure out. I am using breeze to populate a list of projects to be displayed in a table. There is way more info than what I actually need so I am doing a projection on the data. I want to add a knockout computed onto the entity. So to accomplish this I registered and entity constructor like so...
metadataStore.registerEntityTypeCtor(entityNames.project, function () { this.isPartial = false; }, initializeProject);
The initializeProject function uses some of the values in the project to determine what the values should be for the computed. For example if the Project.Type == "P" then the rowClass should = "Red".
The problem I am having is that all the properties of Project are null except for the ProjNum which happens to be the key. I believe the issue is because I am doing the projection because I have registered other initializers for other types and they work just fine. Is there a way to make this work?
EDIT: I thought I would just add a little more detail for clarification. The values of all the properties are set to knockout observables, when I interrogate the properties using the javascript debugger in Chrome the _latestValue of any of the properties is null. The only property that is set is the ProjNum which is also the entity key.
EDIT2: Here is the client side code that does the projection
var getProjectPartials = function (projectObservable, username, forceRemote) {
var p1 = new breeze.Predicate("ProjManager", "==", username);
var p2 = new breeze.Predicate("ApprovalStatus", "!=", "X");
var p3 = new breeze.Predicate("ApprovalStatus", "!=", "C");
var select = 'ProjNum,Title,Type,ApprovalStatus,CurrentStep,StartDate,ProjTargetDate,CurTargDate';
var isQaUser = cookies.getCookie("IsQaUser");
if (isQaUser == "True") {
p1 = new breeze.Predicate("QAManager", "==", username);
select = select + ',QAManager';
} else {
select = select + ',ProjManager';
}
var query = entityQuery
.from('Projects')
.where(p1.and(p2).and(p3))
.select(select);
if (!forceRemote) {
var p = getLocal(query);
if (p.length > 1) {
projectObservable(p);
return Q.resolve();
}
}
return manager.executeQuery(query).then(querySucceeded).fail(queryFailed);
function querySucceeded(data) {
var list = partialMapper.mapDtosToEntities(
manager,
data.results,
model.entityNames.project,
'ProjNum'
);
if (projectObservable) {
projectObservable(list);
}
log('Retrieved projects using breeze', data, true);
}
};
and the code for the partialMapper.mapDtosToEntities function.
var defaultExtension = { isPartial: true };
function mapDtosToEntities(manager,dtos,entityName,keyName,extendWith) {
return dtos.map(dtoToEntityMapper);
function dtoToEntityMapper(dto) {
var keyValue = dto[keyName];
var entity = manager.getEntityByKey(entityName, keyValue);
if (!entity) {
extendWith = $.extend({}, extendWith || defaultExtension);
extendWith[keyName] = keyValue;
entity = manager.createEntity(entityName, extendWith);
}
mapToEntity(entity, dto);
entity.entityAspect.setUnchanged();
return entity;
}
function mapToEntity(entity, dto) {
for (var prop in dto) {
if (dto.hasOwnProperty(prop)) {
entity[prop](dto[prop]);
}
}
return entity;
}
}
EDIT3: Looks like it was my mistake. I found the error when I looked closer at initializeProject. Below is what the function looked like before i fixed it.
function initializeProject(project) {
project.rowClass = ko.computed(function() {
if (project.Type == "R") {
return "project-list-item info";
} else if (project.Type == "P") {
return "project-list-item error";
}
return "project-list-item";
});
}
the issue was with project.Type I should have used project.Type() since it is an observable. It is a silly mistake that I have made too many times since starting this project.
EDIT4: Inside initializeProject some parts are working and others aren't. When I try to access project.ProjTargetDate() I get null, same with project.StartDate(). Because of the Null value I get an error thrown from the moment library as I am working with these dates to determine when a project is late. I tried removing the select from the client query and the call to the partial entity mapper and when I did that everything worked fine.
You seem to be getting closer. I think a few more guard clauses in your initializeProject method would help and, when working with Knockout, one is constantly battling the issue of parentheses.
Btw, I highly recommend the Knockout Context Debugger plugin for Chrome for diagnosing binding problems.
Try toType()
You're working very hard with your DTO mapping, following along with John's code from his course. Since then there's a new way to get projection data into an entity: add toType(...) to the end of the query like this:
var query = entityQuery
.from('Projects')
.where(p1.and(p2).and(p3))
.select(select)
.toType('Project'); // cast to Project
It won't solve everything but you may be able to do away with the dto mapping.
Consider DTOs on the server
I should have pointed this out first. If you're always cutting this data down to size, why not define the client-facing model to suit your client. Create DTO classes of the right shape(s) and project into them on the server before sending data over the wire.
You can also build metadata to match those DTOs so that Project on the client has exactly the properties it should have there ... and no more.
I'm writing about this now. Should have a page on it in a week or so.

JAWR i18n: unit testing javascript when using messages

Our application currently shares messages between the Java and Javascript side. They are stored as resource bundles in the class path, and we have a custom controller that returns all the messages as Json. The client side code look like this:
// This calls the controller to get all the messages
var messages = MessageBundle();
var text = messages.get('my.message', 1);
This is great because we can mock "messages" in our unit tests.
I want to start using JAWR for this, since we already use it for other things. The problem is JAWR generates the following Javascript object:
var text = messages.my.message(1);
This means the code cannot be unit tested anymore unless the unit tests also define a global "messages" variable with the right nested objects. Is there a way around this? Any idea how to extend JAWR to make this unit-testable?
Currently my work around is:
function messages() {
var args = Array.prototype.slice.call(arguments);
var messageId = args.shift();
var messageFunc = window.messages;
messageId.split('.').forEach(function(part) {
messageFunc = messageFunc[part];
});
return messageFunc(args);
}
// Same syntax as the old one, but uses the JAWR object behind the scenes
// This function is easy to mock for a unit test
var text = messages('my.message', 1);
Thanks for any ideas!
Maybe next samples can help you.
1)
function messagesTester(funcPath,id) {
var args=funcPath.split('.'),root=window.messages;
for(var i=0;i<args.length;i++)root=root[args[i]];
return root(id);
// or if more that one parameter for *func*, then, for example:
// return root.apply(null,Array.prototype.slice(arguments,1));
}
var text = messagesTester('my.message',1);
2)
function messagesTester(funcPath) {
var args=funcPath.split('.'),root=window.messages;
for(var i=0;i<args.length;i++)root=root[args[i]];
return root;
}
// var text = messagesTester('my.message')( /*arguments list*/ );
var text = messagesTester('my.message')(1);

Pushlets working with HTML5 canvas or Javascript

Does anyone have experience with Pushlets?
I have been working on it several days. I can make it work on regular javascript, but when I add HTML canvas and use javascript to draw something based on the "push"ed data, it doesn't work.
In my simple example:
document.getElementById('sometag').innerHTML = event.get("x");
document.getElementById('sometag').innerHTML = event.get("x");
...
document.getElementById('sometag').innerHTML = event.get("x");
if I keep all these regular tag there is no problem, but when I add:
document.getElementById('canvas').getContext('2d').fillRect(....);
it doesn't work. The error says can not receive XML data.
So any help? Thanks in advance.
You probably need to evaluate scripts in HTML pushed from server. Something like this:
function extractScripts(html) {
// based on PrototypeJs
var ScriptFragment = "<script[^>]*>([\\S\\s]*?)<\/script>";
var matchAll = new RegExp(ScriptFragment, "img");
var matchOne = new RegExp(ScriptFragment, "im");
return (html.match(matchAll) || []).map(function(scriptTag) {
return (scriptTag.match(matchOne) || ['', ''])[1];
});
}
function evalScripts(html) {
return extractScripts(html).map(function(script) { return eval(script) });
}

Categories

Resources