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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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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
169 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
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Xamarin.Forms and Prism NavigationParameters implementation

I am developing a Xamarin Forms project and use Prism Library as tool to implement the MvvM pattern. I have two views: PersonViewModel: Summary and has Edit button PersonEditViewModel: Details, and ...
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2answers
1k views

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 ...
0
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1answer
31 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 ...
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46 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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4answers
21k views

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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1answer
509 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 ...
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2answers
1k views

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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2answers
118 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
76 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 ...
2
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1answer
237 views

When to use The Messenger (Mediator) Pattern in MVVM design

I got confused with the role of the Messenger in MVVM. I see contradictory articles about it. This Article by MSDN by: Communicating from the View-Model to the View Observant readers will ...
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3answers
356 views

When to use Parameters and When Not to C#

I am have an application using MVVM pattern. It takes a user ID and returns a table with the user's bookmarks. I am trying to decided if it is better practice to include parameters in my model's ...
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2answers
160 views

How should I Implement a general method that could be used across several view models?

Currently I have implemented a method in to a model to take a screen shot like so E.G. Interface public interface ICapture { void CaptureMethod(); } This is the model that implements that ...
4
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1answer
251 views

Where is it better to implement Copy/Cut/Paste in MVVM?

I am working on a project using C#/WPF and following MVVM pattern. This project is designed for touch screens. The major objects of the program are the following: We have Programs which contain ...
18
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1answer
4k views

Is there a good formal pattern to manage state in MVVM?

I have started learning about Redux and React in the web-world, and the more I learn about it the more I'm realizing how painful state management is in the desktop-world with WPF's MVVM-style ...
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1answer
150 views

Giving Viewmodels access to application wide Model in MVVM

I am practicing building applications using MVVM and WPF+C# by making a "finance application". The application contains several views with their own ViewModels. The views are in a hierarchy and are ...
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2answers
5k views

How to separate the ViewModel from the Model, yet associate them with each other based on the Model?

In a wpf application, a Model object is created either from scratch or deserialized from some .xml file. To create a connection to the ViewModel, the following method (on the Model!) is used by the ...
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1answer
766 views

Where to keep persistent services in MVVM architecture?

In an MVVM application I need to use some services that are persistent, e.g. network services like P2P and WCF where the main "engine" or server endpoint must remain up and running during the lifetime ...
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1answer
71 views

MVVM distinguish between Model and View-Model and Models relashionships on reactive architecture

This should be a simple MVVM - reactive architecture question, something that I miss probably. I'll start with a context example: I have a Music Tracks Player application with 2 models Player and ...
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1answer
128 views

MVC / MVVM principles

I'm currently working on updating some old projects (inherited stuff) and I keep running into various small issues with the architecture. Namely monolithic classes too tightly coupled. One example ...
5
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1answer
262 views

Approach for Constructing View Models in Complex MVVM Application

I'm struggling with the design in a WPF MVVM application. In a few courses I've taken, they say that having a lot of parameters in a constructor is a code smell, but they never address how to deal ...
3
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1answer
73 views

View-model architecture

I have two screens: A screen with a list of items, where every item in the list has "Show Details" and "Update buttons" An item details screen. The "Show Details" button navigates to item details ...
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3answers
652 views

State of selected items in view or viewmodel?

Myself and my colleague were having a discussion about MVVM and how lists and selected items should be stored in view / viewmodel. I think the viewmodel should only offer up the data and allow the ...
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1answer
114 views

MVC: How to use data model list in recursive views

I am trying to learn web app MVC in PHP.Most of the articles discussed about 1-to-1 MVC pattern given bellow Controller: gets user request & update model, Model: receives orders form Controller &...
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0answers
47 views

How does “redux” decouple the different components so they can be tested separately in unit tests?

In the past we saw a big move from traditional MVC to MVVM for user interfaces: One of the primary motivations for MVVM is that the view and viemmodel are competely indepedently of each other and ...
5
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1answer
604 views

MVVM Persistence from view model

I'm new to MVVM, I get the general idea, but there's one thing that I've been having a tough time finding an answer for. Inevitably an application will have a save button in the UI. The UI talks to ...
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3answers
801 views

Modular Filter Architecture for WPF

I am creating a little stock-management tool for private use. I have different views, which need similar but different filters. As an example I have a "current stock" list where I can filter for ...
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0answers
996 views

Proper implementation of Repository Pattern with MVVM in WPF

I am currently refactoring a WPF application that is built on the principles of the Repository Pattern. It uses Entity Framework as its ORM, and is Database First. Each of those entities is wrapped by ...
0
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1answer
105 views

Adding an additional layer between domain model and view model necessary?

I am working on a Xamarin application (Mvvm using Prism), I am also leveraging OData for communication between my backend and the mobile application. The structure of my Mobile app is as follows: ...
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0answers
38 views

Where to keep the code for new instance of an object in iOS project?

Example: There is a KingDetailViewController class with the following code. // MARK: - New Instance extension KingDetailViewController { class func newInstance() -> ...
20
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6answers
13k views

Should we bind view to a model property or ViewModel should have it's own..?

I am starting a project with following technical environment : .Net 4.0, Entity Framework 4.0, WPF with MVVM Architecture I saw lots of examples on the net, some books with this environment. In some ...
2
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1answer
3k views

When using MVVM, is it okay to use property injection on a view model in WPF?

I am rather new to the concept of MVVM in C#/.NET WPF projects. The way I understand it, the view-model is supposed to lessen the amount of code-behind required to display data on a form. I try to do ...
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1answer
68 views

Ext JS: Designing a base class and override it

I'm trying to define a base class and override it's items on different inherited sub-classes. I'm following MVVM pattern to fetch records from backend. Created several stores and formulas within ...
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0answers
172 views

Should I populate view model inside or before creating it

I'm not sure if softwareengineering exchange is right for the question. I need to populate view model with some values I query from the database. I do it like: var db = new NPoco.Database(...
0
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1answer
991 views

Duplicating Domain Model in View Model or not

I have an XML file that contains configuration information for a system. I can serialize/deserialize the XML into a hierarchy of objects that describe the configuration (and no more) and then pass ...
2
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1answer
217 views

ASP.Net MVC When ViewModel properties vs Ajax calls in view

When is it more appropriate to use asynchronous calls from the view to get data vs prepopulating it server-side when creating the instance of the viewmodel? For instance, if my view has some dropdown ...
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2answers
545 views

Should I remove “everything” from my controller in MVVM?

I'm working with Xamarin and we are following the MVVM design pattern. For those who don't know what Xamarin is, it's a technology that allows us to build iOS and Android apps with shared code. ...
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4answers
413 views

Avoid type checking but preserve separation of concerns

I'm working on an MVVM project and trying to preserve separation of concerns. Our current architecture has an entity framework model and MVVM light view and viewmodel projects. I'm working ViewModel ...
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2answers
517 views

MVVM. Is it a code smell when view model has properties with names show/hide/display that semantically belong to view?

I've lately been involved with WPF and looked into MVVM. I understand that view model shouldn't be aware of view. However, sometimes I come across situation where my initial instinct is to write ...
2
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1answer
77 views

Thick viewmodel results in thin model

How thick should a viewmodel be? For example, should my viewmodel or model handle the actual filtering? For example, let's say I have a Roster object holding a collection of Users which are ...
2
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1answer
213 views

What's the M in MVVM?

Is the M (model) in MVVM equal to business logic + data? Or is it just supposed to be data/state for the view? Background: In a project we use "model" as a name for an object that holds presentation ...
6
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4answers
2k views

Clean, Modular Code vs MV* Frameworks [closed]

I've been hearing a lot about the "new" MV* frameworks. I've tinkered with KnockoutJS (I created an invoicing application), but I much prefer to write clean, modular code in raw JavaScript - ...
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2answers
2k views

Overall view validation with a datagrid and keeping to MVVM

I am struggling to find a good architecture for what must be a common problem Enable/Disable a button in a View that contains a datagrid, and has validation requirements on the cell, row and ...
3
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1answer
3k views

WPF MVVM Loading data on startup

I am building a simple master-details GUI using WPF/MVVM/Prism for some data coming from a Restful service. I have the main window as my main view with a corresponding view model. I have a user ...
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2answers
3k views

How to implement validation before setting a property value in MVVM (WPF)

Scenario. ViewModel has a property State. View has a ComboBox that allows to change value of State. ViewModel needs to run some validation (call bool ValidateState(State value) method) before setting ...
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2answers
4k 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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1answer
516 views

Is it right to have dependenties to my Viewmodel from data acces layer and view layer

Context In my application I use the MVVM pattern. I'll have a ViewModel that can contains information of a student. This viewmodel is used to communicatie between my view and model. I use ASP.net ...
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2answers
202 views

Should I create a (new) project for shared UserControls?

Context: I'm creating some applications to help me on my daily tasks, it does not connect anywhere and the only "data" it has to deal with is the parameters that I enter on the input fields. This is ...
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2answers
302 views

Should i be using My own MVVM implementation?

Hi there i've been into MvvM and modular design the last few days, i find it really nice design principle that be scaled and maintained really well. But here is the thing, i see there are multiple ...