Questions tagged [mvvm]

The Model View ViewModel (MVVM) is an architectural pattern used in software engineering that originated from Microsoft as a specialization of the presentation model design pattern introduced by Martin Fowler.

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Loose Coupling Presenter to View in MVP

We work in a Java shop here and our web application uses an implementation of the MVP architectural pattern. Our manager comes from a .NET world, where he has been exposed to the MVVM design pattern. ...
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What is the proper way to handle with View and ViewModel in WPF?

Currently, I'm making an Editor with MVVM pattern in WPF. Editor simply take an instance of a specific type as a reference and modifies it. The following code is the expected usage when editor ...
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1answer
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Extract Exception handling MVVM

I noticed a pattern in my code, where im repeating a solid amount of code. Let's say my application has 2 layers. UI and Services. I have a FileService class, that has a CopyTo method. Now there are 2 ...
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2answers
110 views

Layered Model-View-ViewModel design

I am designing an application using C# and Windows Presentation Foundation (WPF). I would like to follow (at least) the very basic rules of software architecture, like dependicies only going in one ...
2
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1answer
68 views

Does passing a view model down to a properties violate MVVM or OOP?

I'm new to MVVM but experienced in OOP. I have an easy solution to my problem, but I'm not sure if it violates MVVM or OOP or if it is a good practice. I have a set of ViewModel classes in my WPF ...
2
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1answer
585 views

MVVM viewmodel to view correlation in adaptive UI

I am making an mvvm application for the uwp platform and I am looking for advice on the following matter. Take for example the windows 10 e-mail application, which when full screen displays both the ...
32
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4answers
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How to choose NOT to use a framework (Caliburn.Micro, etc.) in a given MVVM application?

I have once started a MVVM/WPF project, which was eventually built and deployed, and for that I studied a lot of the Caliburn.Micro MVVM Framework. The fact is: I ended up not using Caliburn.Micro for ...
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2answers
726 views

Propagating Data to multiple ViewModels - C#

I'm a bit new to MVVM, but here's my dilemma: I have a model (or models, but let's keep it simple) I want to show that model data on multiple different views. Ok, so ViewModel for each view gets ...
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1answer
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How to populate view models

So let's say I have a view model, representing a student. The view model is corresponding to a student model, from which the data comes. What I am struggling with, is how to populate the fields in the ...
0
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1answer
69 views

How do I plan my refactor of my android app for better architecture?

The current structure of my app is as follows: One activity and multiple fragments (about 25 fragments) One huge monolithic repository One huge monolithic viewmodel Databinding is being used but with ...
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1answer
432 views

Throttling notifications from child ViewModel to parent ViewModel

I have a child view-model which notifies on a property change: public class ChildViewModel : INotifyPropertyChanged { private bool isSelected; public bool IsSelected { get => ...
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1answer
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What is the correct architecture for 4 MVVM synchronized collections related to groups and filters inside a WPF application?

I have a small architectural problem with MVVM. In this question I will note Model through M and ViewModel through VM. I have 4 collections that must be synchronized, and the items in them must have ...
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2answers
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Clean Architecture: What is the View Model?

In his book 'Clean Architecture', Uncle Bob says that the Presenter should put the data that it receives into something he calls the 'View Model'. Is this the same thing as the 'ViewModel' from the ...
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0answers
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Common business logic in android MVVM

Requirement I am currently working on an android application that uses MVVM, live data and databinding. I have a use-case where I need to show a Comment button in multiple screens in my android app. ...
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41 views

WPF MVVM EventAggregator Cons?

We have a wpf mvvm application with a lot of "panes". Just like the draggable panes in visual studio for example. All of these are individual usercontrols with their own viewmodels and im trying to ...
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2answers
67 views

MVVM construction questions

I am trying to understand how MVVM works. Here are two examples (in Andrdoid) on how I understand it should work, please tell me if I understood correctly. I currently want to make a list of ...
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3answers
9k views

MVVM Correct way to switch between views occupying the same footprint on the screen

An example is switching the main view according to the selected item in a hamburger menu. Also sometimes it is just a small part of the GUI that changes according to the application state or according ...
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2answers
53 views

Should a view-model be coupled to a view or to a model?

That is, let's say I have a model that's used in several views. Should I create a single view model to represent it across all those views, or should I create a separate view model for each view that ...
3
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5answers
634 views

WPF UserControl Reuse With MVVM

I'm struggling to find an elegant and idiomatic way of coding the following scenario using the MVVM paradigm in WPF and was wondering how other people would approach it. I have a UserControl in my ...
2
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1answer
3k views

What is the good way of sharing specific data between ViewModels

We have IAppContext which is injected into ViewModel. This service contains shared data: global filters and other application wide properties. But there are cases when data is very specific. For ...
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2answers
89 views

Dependency relations in MVVM and the place of the controller

I know there is plenty of questions about this, but there is a lot of seemingly conflicting information. My assumption: The viewmodel is an abstraction of the view, an interface to the business ...
0
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1answer
52 views

CRUD actions rexponsibility in the MVVM

In Form-based application (WPF/MVVM/SQLServer), consider the form that handles the classical actions that you can perform on any entity. Create Read Update Delete The problem, in general terms, is ...
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2answers
133 views

Services injected with factories

I face an issue where I want to inject Entity Frameworks DbContext into a service class, in a WPF application. The problem is that the service classes are instantiated and contained by the view models....
2
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2answers
408 views

Uncle Bob's Clean Architecture - Dealing with anemic interactors, tiering, and front-end MVVM

Background In Uncle Bob's Clean Architecture, use case interactors are responsible for the orchestration of business objects to accomplish some user goal. As an easy example, an e-commerce application ...
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63 views

confusion for view's and viewmodel's responsibility in mvvm architecture in android

i have a confusion about what code should be placed in view and what in viewmodel for example click events here is a snippet code of google ToDo app example for showing application architecture (...
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1answer
289 views

IoC/DI + “normal” constructor arguments mvvm

I am using unity in C# to achieve dependency injection and inversion of control. What if I have a class, let's say a viewmodel, that depends on several services like a repository, a validator and a ...
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3answers
131 views

How to design and join more complex entities

I am developing a small ERP software. I'm wondering how to design entities as well as where to join them. I'm just gonna start with an example, that makes it way easier. Say I'm modelling a ...
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2answers
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Adding model into another view model's collection

The Setup So I'm working on a project in which there exists a MainViewModel class. This MainViewModel contains a list of Soldiers through an observable collection. I have a button in the MainView ...
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0answers
54 views

Do MV* architectural patterns apply not only to OO languages but also functional languages?

I am learning about MV* architectural patterns, thanks to the help from several answers here. I learned that they are used for designing the architectures of user interactive applications. I also ...
2
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2answers
98 views

Where should objects be built from view-models in a layered architecture?

Having the following classes: Person.cs namespace Project.Domain { public class Person { public int Id { get; set; } public string Name { get; set; } public decimal ...
3
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1answer
2k views

Should MVVM models have behaviour?

I am trying to wrap my head around MVVM and "models should not have behaviour". If my getter depends on an environment variable, should it be in the model or viewmodel? Does it make a difference if ...
2
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1answer
76 views

Provide overall application status in global exception handler/crash report

In my UI application (WPF/C#, using MVVM design pattern), I have implemented a global exception handler which catches all unexpected (hence uncaught) exceptions and reports the application crash to ...
0
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1answer
661 views

Do shared ViewModels contradict MVVM?

I want to follow the MVVM app architecture. I also need to have some communication between some fragments. But the official approach is pretty confusing. Taken from the docs (https://developer....
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1answer
2k views

Check location permissions with MVVM in Android?

I need to request runtime location permissions for the FusedLocationProviderClient api and, once I have them, obtain Location objects and feed them to an algorithm that will make a query to an ...
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1answer
68 views

When to fetch/send data in an Android application

I am currently creating an Android application and I have the following questions: We have a server which provides data for the app in form of a REST-JSON-API. The App is following the MVVM ...
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2answers
2k views

Where to call OnPropertyChanged

With WPF and MVVM, properties of the ViewModel are bound to UI elements. When a property changes, its set accessor calls OnPropertyChanged which in turn raises the PropertyChanged event of the ...
4
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3answers
2k views

Is using getters in XAML view-models a bad thing?

I've recently had an argument with a colleague about using getters (without setters) in a view-model classes used by XAML. Example: public string FullName { get { return $"{FirstName} {...
5
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3answers
551 views

How to avoid duplication of types in MVVM

I'm learning the MVVM pattern and something that comes up often is a duplication of data-types. Say I have a Person datatype. Intuitively I want it to look like this: public class Person { ...
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0answers
68 views

How to avoid circular dependency from abstracting navigation in desktop application?

I am trying to abstract some functionality from my desktop application (JavaFX) for changing views. So, what I am thinking is: Navigator interface with methods like goToAccountsOverview(), ...
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3answers
293 views

How do I architect an iOS app when multiple view models must know when the model has changed?

I'm using MVVM and I have an app with a UITabBarController, the Main tab of which is a list of publications and the other is a Search screen where they can search for publications. Searching returns a ...
0
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2answers
703 views

Is it okay to pass my model into my view model via its constructor through MVVM practices?

public class LDLTrackViewModel : RailwayViewModel { private LDLTrack _ldlTrack; public LDLTrack LDLTrack { get => _ldlTrack; set { _ldlTrack = value; ...
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1answer
185 views

Where to store calculated values of an entity

Trying to figure out the best place to store calculated properties related to a base entity class for use through out the application, namely in view models and DTOs. For example, a base entity class ...
1
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1answer
489 views

Setters in ViewModels

So I have started reading some books and articles on architecture. They all state (put a little simply) that you should never let your view access the model directly, when using a Model-View-ViewModel ...
0
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1answer
139 views

Where do I save a Canvas “center position” coordinate in an MVVM architecture?

Assume I have a canvas that has rendered shapes. I can drag-move around that canvas as if I was in a zoomed in image to move all shapes around. Between the Model and ViewModel I have a ServiceLayer (...
0
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1answer
160 views

Designing a WPF / MVVM architecture where view behavior changes in different states

As part of my bachelors thesis, I'm trying to develop something akin to a painting program. That means, I have a toolset, be it selection, drawing, highlighting, etc. I'll have a canvas that displays ...
1
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1answer
418 views

What is the proper way to change the View from a ViewModel when using the MVVM pattern?

I'm trying to follow the Model–View–ViewModel pattern in a Xamarin application and am wondering how the View should be able to change when a given ViewModel is finished. Below I have listed the ideas ...
4
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1answer
2k views

Why can’t ViewModels communicate with each other?

Can someone explain concretely why it is not desirable for ViewModels to communicate directly with other view models? It seems to me that for virtually any UX application there will be a “root” view (...
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0answers
90 views

When not to use View Services in MVVM design pattern?

I'm using the MVVM design pattern in my application which is comprised of, A Xamarin.IOs project (View Layer) A Net Standard project (Common Layer) A Xamarin.Android project (in the future) (View ...
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2answers
219 views

What is better approach to implement dependency injection using MVVM Architecture?

I need to use DispatchQueue within controller and pass it as dependency. This is what I have tried so far and worked out two solutions. Need to ask what is better and in common use by other developers:...
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1answer
95 views

MVVM/WPF/Appropriate place for code

I have a question about MVVM design, and where I should put some code that I would like to add. My application queries active directory for computers and displays the list to the user. Selecting a ...

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