C#•4mo ago

✅ How to access specific fields from an [ObservableProperty] ObservableCollection<Object>?

Hoping to pick someone's brain on MVVM and MAUI. So I have a ViewModel that looks like:

public partial class TermsViewModel : ObservableObject
{
    public TermsViewModel()
    {
        Terms = new ObservableCollection<Term>();
    }
    
    [ObservableProperty]
    ObservableCollection<Term> terms;
}

public partial class TermsViewModel : ObservableObject
{
    public TermsViewModel()
    {
        Terms = new ObservableCollection<Term>();
    }
    
    [ObservableProperty]
    ObservableCollection<Term> terms;
}

and I want to have the xaml create each of the objects in the ObservableCollection... But the items are of type Term, so how do I tell the xaml to access the IdText of the Term object and print that?

    <CollectionView
        ItemsSource="{Binding Terms}">
        <CollectionView.ItemTemplate>
            <DataTemplate x:DataType="x:String">
                <SwipeView>
                    <SwipeView.RightItems>
                        <SwipeItems>
                            <SwipeItem Text="Delete" 
                                       BackgroundColor="Red"/>
                        </SwipeItems>
                    </SwipeView.RightItems>
                    <SwipeView.LeftItems>
                        <SwipeItems>
                            <SwipeItem Text="Edit" 
                                       BackgroundColor="Orange"/>
                        </SwipeItems>
                    </SwipeView.LeftItems>
                </SwipeView>
            </DataTemplate>
        </CollectionView.ItemTemplate>
    </CollectionView>

    <CollectionView
        ItemsSource="{Binding Terms}">
        <CollectionView.ItemTemplate>
            <DataTemplate x:DataType="x:String">
                <SwipeView>
                    <SwipeView.RightItems>
                        <SwipeItems>
                            <SwipeItem Text="Delete" 
                                       BackgroundColor="Red"/>
                        </SwipeItems>
                    </SwipeView.RightItems>
                    <SwipeView.LeftItems>
                        <SwipeItems>
                            <SwipeItem Text="Edit" 
                                       BackgroundColor="Orange"/>
                        </SwipeItems>
                    </SwipeView.LeftItems>
                </SwipeView>
            </DataTemplate>
        </CollectionView.ItemTemplate>
    </CollectionView>

I'm not sure how best to handle a "complex" object vs. just an ObservableCollection<string>. I essentially want the term.Name to be displayed for each Term object in the Collection, but when the term.Name is tapped in my app, I want it to reference pass the term.Id to an eventual call to open a CoursePage(term.Id)

108 Replies

leowest•4mo ago

For a start, ObservableCollection does not required ObservableProperty, it already is an observable object.

public partial class TermsViewModel : ObservableObject
{
    public TermsViewModel()
    {
        Terms = new ObservableCollection<Term>();
    }
    
    public ObservableCollection<Term> Terms { get; set; }
}

public partial class TermsViewModel : ObservableObject
{
    public TermsViewModel()
    {
        Terms = new ObservableCollection<Term>();
    }
    
    public ObservableCollection<Term> Terms { get; set; }
}

In addition to that you should not need to specify the DataType and to bind the properties it would be as simple as using {Binding Id} or {Binding Name} https://learn.microsoft.com/en-us/dotnet/maui/user-interface/controls/collectionview/populate-data?view=net-maui-8.0 https://learn.microsoft.com/en-us/dotnet/maui/xaml/fundamentals/data-binding-basics?view=net-maui-8.0 For more information these links should be of help

DaClownieOP•4mo ago

Phenomenal, I’ll read up and use your information to start. I appreciate the time you put in to your answer and I’ll update if I make progress or hit snares. Thanks! Hey, so I'm hitting build time errors when trying to reference the Name and IdText fields of the Term objects inside the ObservableCollection we talked about Rider showed no issues until I tried to Build, visual studio on windows recognizes that it can't make the connection, but I can't quite figure out a way to resolve it

DaClownieOP•4mo ago

DaClownieOP•4mo ago

I still can't figure out what I'm missing to make this work. The IDE knows its a Term, but at build time it tries to find the property IdText inside the TermsViewModel and not in the Term.

DaClownieOP•4mo ago

If I remove the IdText you see whats on the lines right below, Label "Text={Binding}" /> gets annotated by Rider with DataContext=Term

leowest•4mo ago

can you show me your model preferable if u have a github its easier

DaClownieOP•4mo ago

using System;
using System.Collections.Generic;

namespace LibrandriaMAUI.Models;

public partial class Term
{
    
    public Guid Id { get; set; }

    public string Name { get; set; } = null!;

    public DateTime StartDate { get; set; }

    public DateTime EndDate { get; set; }

    public string UserId { get; set; }

    public string? IdText { get; set; }

    public DateTime DateCreated { get; set; }

    public DateTime DateModified { get; set; }

    private Term() { }

    public Term(string name, DateTime startDate, DateTime endDate,
        string userId)
    {
        Id = Guid.NewGuid();
        Name = name;
        StartDate = startDate;
        EndDate = endDate;
        UserId = userId;
        IdText = Id.ToString();
    }
}

using System;
using System.Collections.Generic;

namespace LibrandriaMAUI.Models;

public partial class Term
{
    
    public Guid Id { get; set; }

    public string Name { get; set; } = null!;

    public DateTime StartDate { get; set; }

    public DateTime EndDate { get; set; }

    public string UserId { get; set; }

    public string? IdText { get; set; }

    public DateTime DateCreated { get; set; }

    public DateTime DateModified { get; set; }

    private Term() { }

    public Term(string name, DateTime startDate, DateTime endDate,
        string userId)
    {
        Id = Guid.NewGuid();
        Name = name;
        StartDate = startDate;
        EndDate = endDate;
        UserId = userId;
        IdText = Id.ToString();
    }
}

The github is set to private unless I can add specific users. I have to learn how to hide certain bits of info before i can make it public (connection strings, etc)

leowest•4mo ago

and here are u binding via DI?

DaClownieOP•4mo ago

probably just need to pan out a proper .gitignore but i haven't got there

leowest•4mo ago

I mean u could make it public for a short period so I can clone it and then hide it again

DaClownieOP•4mo ago

give me a moment

leowest•4mo ago

for connection strings etc usually env vars are used or things u dont want to commit to your git and yes also a gitignore for obvious reasons because u dont want to push the bin folder etc https://www.jetbrains.com/help/rider/Run_Debug_Configuration.html#envvars-progargs

DaClownieOP•4mo ago

check your messages sent it privately

leowest•4mo ago

sadly I dont get dms, u can send here nad delete short after k

DaClownieOP•4mo ago

tell me when i can delete and set private again :kek:

leowest•4mo ago

see like u dont want ever to push these

leowest•4mo ago

u can try running a dotnet new gitignore that folder alone is probably making your project like 100~+ mbs to upload to git haha

DaClownieOP•4mo ago

ok done, will it automatically remove things from the repo that is being ignored? or will I need to clean that up

leowest•4mo ago

mmm it should does rider not have a git changes u can view?

DaClownieOP•4mo ago

Just shows changed files, I'll deal with that part a bit later, add it to my todo list :kek:

leowest•4mo ago

the binding looks fine, let me delve into I can also see u wired things right in the DI

DaClownieOP•4mo ago

Ok, thats good to know I might have to rework how the database works, or how I interact with it. As it stands now, I need to add any IP that tries to connect to the Db to an allowed conneciton list. Probably need some sort of backend api that does the routing so its "local" (i'm spitballing, don't know what i'm talking about it, but assuming something like that is the proper methodology) I could also just host my own instance on my server, but I didn't want to spend all that time lol

leowest•4mo ago

I mean depends is this a external database hosted somewhere?

DaClownieOP•4mo ago

yep

leowest•4mo ago

then u can't run it locally without creating your own

DaClownieOP•4mo ago

I have an unRAID server that I could run a MySQL docker on

leowest•4mo ago

you could dump all the scripts and create a local one for testing purpose if u want

DaClownieOP•4mo ago

I figured just grabbing some web hosting would make my life simpler, but as i've been going, nothing has been easy lol

leowest•4mo ago

also keep in mind this

leowest•4mo ago

you dont use the private field Community Toolkit creates public ones for u to use so those should be in your GetUserId Username and Password

leowest•4mo ago

DaClownieOP•4mo ago

ohhhh right

leowest•4mo ago

and for your models

DaClownieOP•4mo ago

I also know there's no hashing or salting of passwords happening, I was going to just roll that in after

leowest•4mo ago

if u have a string that will never be empty you can append required to it i.e.:

leowest•4mo ago

DaClownieOP•4mo ago

I did have a question just on best practice while I have you here... Currently I have the db creating the DateCreated, DateModified fields when the database is added to or updated by EF, should I have all that logic on the c# side of things and remove that logic from the db?

leowest•4mo ago

ok I see the problem u will have to define the datatemplate type

<DataTemplate x:DataType="model:Term">

<DataTemplate x:DataType="model:Term">

and

xmlns:model="clr-namespace:LibrandriaMAUI.Models"

xmlns:model="clr-namespace:LibrandriaMAUI.Models"

I usually let the db handle those also u should use DateTimeOffset instead

DaClownieOP•4mo ago

damnit ok. I had x:DataType="string" in there before from the example and I was like well i'm not just displaying strings, but the IDE was not mad about anything so I forgot I did that lol oh for UTC time

leowest•4mo ago

$datetimelie

MODiX•4mo ago

please please please get into the habit of using DateTimeOffset instead of DateTime in your code everywhere you possibly can. DateTimeOffset contains the UTC offset with the data so is lossless. DateTime is very very weird in how it stores data. DateTime only knows UTC and "local" time. But your local time zone can change! Laptops easily move across state lines, even while an app is currently running. (So you are in California running an app, put some DateTime instance in memory, hop on a plane to New York, then resume your app 3 time zones ahead. What on earth will be contained within the DateTime instance?) But wait, this was a lie. DateTime actually has 3 ways it keeps track of time: UTC, local (which can change while an app is running), and unspecified (unknown, essentially). (Unknown = I don't know if it's UTC or local, the app will figure it out later and call ToUniversal or ToLocal before calling ToString or any comparison routine.) But wait, this was a lie. DateTime actually has a secret fourth way of storing data that's not exposed in the standard API surface! It's truly an abomination of a type. All of this nonsense is irrelevant if we just pretend DateTime doesn't exist and we instead use DateTimeOffset everywhere.

- GrabYourPitchforks (start: https://discord.com/channels/143867839282020352/143867839282020352/988353756108312607)

leowest•4mo ago

also please 👆 you really should not mark it as observable also instead of using ObservableObject you should create a common class to inherit from i.e.:

public partial class BaseViewModel : ObservableObject;

public partial class BaseViewModel : ObservableObject;

DaClownieOP•4mo ago

ah, that was how the example I followed did it, I can revise Is this so if I need to make changes to how I make models, I can change all at once, but they all inherit the ObservableObject if they inherit BaseViewModel? Ok, let me fix the original databinding issue and then I'll continue reading this, gimme a minute

leowest•4mo ago

and last but not least for organizational purposes for EF core I prefer keeping the Entity configuration next to the class by using IEntityTypeConfiguration, here is an example:

public class Term
{
    public Guid Id { get; set; }

    public string Name { get; set; } = null!;

    public DateTime StartDate { get; set; }

    public DateTime EndDate { get; set; }

    public required string UserId { get; set; }

    public string? IdText { get; set; }

    public DateTime DateCreated { get; set; }

    public DateTime DateModified { get; set; }
}

public class TermConfigurator : IEntityTypeConfiguration<Term>
{
    public void Configure(EntityTypeBuilder<Term> entity)
    {
        entity.HasKey(e => e.Id).HasName("PRIMARY");

        entity.Property(e => e.DateCreated)
            .HasDefaultValueSql("CURRENT_TIMESTAMP")
            .HasColumnType("datetime");
        entity.Property(e => e.DateModified)
            .ValueGeneratedOnAddOrUpdate()
            .HasColumnType("datetime");
        entity.Property(e => e.EndDate).HasColumnType("datetime");
        entity.Property(e => e.IdText)
            .HasMaxLength(36)
            .HasComputedColumnSql("insert(insert(insert(insert(hex(`id`),9,0,_utf8mb4'-'),14,0,_utf8mb4'-'),19,0,_utf8mb4'-'),24,0,_utf8mb4'-')", false);
        entity.Property(e => e.Name).HasMaxLength(64);
        entity.Property(e => e.StartDate).HasColumnType("datetime");
        entity.Property(e => e.UserId).HasMaxLength(36);
    }
}

public class Term
{
    public Guid Id { get; set; }

    public string Name { get; set; } = null!;

    public DateTime StartDate { get; set; }

    public DateTime EndDate { get; set; }

    public required string UserId { get; set; }

    public string? IdText { get; set; }

    public DateTime DateCreated { get; set; }

    public DateTime DateModified { get; set; }
}

public class TermConfigurator : IEntityTypeConfiguration<Term>
{
    public void Configure(EntityTypeBuilder<Term> entity)
    {
        entity.HasKey(e => e.Id).HasName("PRIMARY");

        entity.Property(e => e.DateCreated)
            .HasDefaultValueSql("CURRENT_TIMESTAMP")
            .HasColumnType("datetime");
        entity.Property(e => e.DateModified)
            .ValueGeneratedOnAddOrUpdate()
            .HasColumnType("datetime");
        entity.Property(e => e.EndDate).HasColumnType("datetime");
        entity.Property(e => e.IdText)
            .HasMaxLength(36)
            .HasComputedColumnSql("insert(insert(insert(insert(hex(`id`),9,0,_utf8mb4'-'),14,0,_utf8mb4'-'),19,0,_utf8mb4'-'),24,0,_utf8mb4'-')", false);
        entity.Property(e => e.Name).HasMaxLength(64);
        entity.Property(e => e.StartDate).HasColumnType("datetime");
        entity.Property(e => e.UserId).HasMaxLength(36);
    }
}

and then you can group call all of those like this

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.UseSerialColumns();
    modelBuilder.ApplyConfigurationsFromAssembly(typeof(LibrandriaDbContext).Assembly);
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.UseSerialColumns();
    modelBuilder.ApplyConfigurationsFromAssembly(typeof(LibrandriaDbContext).Assembly);
}

yes but also more than that you could have a ItemsSources made of BaseViewModel and then changing a page based on what u select from that menu and it would wire the view so there is more to it

leowest•4mo ago

this is what I wanna see next in your project

leowest•4mo ago

:Ok:

DaClownieOP•4mo ago

Your expectations of me are unrealistic, but i love you for it :kek:

leowest•4mo ago

not at all, in this time we've been talking I did it and I am sure u can aswell there was nothing overcomplex I had to do to achieve that

DaClownieOP•4mo ago

Would you want to look at one other part? I don't have the change up on github yet because I was trying to figure out how to do it

leowest•4mo ago

what would that be

DaClownieOP•4mo ago

So in the constructor for TermsViewModel() i have Terms = new ObservableCollection<Term>; I wanted to populate that ObservableCollection with the LibrandriaManager method for public async Task<List<Term> LoadTermList()

leowest•4mo ago

ah good I also wanted to talk about your SQLFunctions instead you should create services and take advantage of the DI that would be the proper way MVVMS

DaClownieOP•4mo ago

but it returns a type Task<List<Term>> which can't be used in the new ObservableCollection<Term>(LoadTermList());

leowest•4mo ago

well its an async method u have to await

DaClownieOP•4mo ago

oh jesus christ

leowest•4mo ago

but either way u dont want to do that in the constructor loading anything in the constructor is not good what u should do is

DaClownieOP•4mo ago

I can put the await in those parentheses can't I

leowest•4mo ago

in the ContentPage you create a Loaded event then you wire that to your vm

DaClownieOP•4mo ago

oh in the code behind? I was in the process of phasing the SQLFunctions out for instancing LibrandriaManager to remove all the static nonsense i was doing

leowest•4mo ago

so it somewhat looks like this

leowest•4mo ago

yes and u do that with services

DaClownieOP•4mo ago

So I'd create a builder.Services.AddSingleton<LibrandriaManager>(); in my MauiProgram.cs?

leowest•4mo ago

for example:

public class UserService
{
    private readonly LibrandriaDbContext _database;
    public UserService(LibrandriaDbContext database)
    {
        _database = database;
    }

    public async Task<User> GetUser(int id)
    {
        return await _database.FirstOrDefaultAsync(x => x.Id == id);
    }
}

public class UserService
{
    private readonly LibrandriaDbContext _database;
    public UserService(LibrandriaDbContext database)
    {
        _database = database;
    }

    public async Task<User> GetUser(int id)
    {
        return await _database.FirstOrDefaultAsync(x => x.Id == id);
    }
}

then you register it in your DI and you can pass that to your ViewModel in the constructor and have access to it in the same way you already do LibrandriaDbContext

DaClownieOP•4mo ago

I have a LibrandriaDbContext in there, but not the LibrandriaManager

leowest•4mo ago

beyond that u would create specific services for each model as needed I would not make a Manager that does everything

DaClownieOP•4mo ago

ohhh, get rid of a central file idea entirely

leowest•4mo ago

yes it would be just a massive confusing file also SRP

DaClownieOP•4mo ago

So I should create a new Folder for Services, and create a Service for each ViewModel that needs it

leowest•4mo ago

yes u could do that I prefer using a VSA approach here because its easier to manage everything from a organizational PoV

DaClownieOP•4mo ago

whats VSA

leowest•4mo ago

$vsa

MODiX•4mo ago

* https://www.youtube.com/watch?v=T-EwN9UqRwE * https://codeopinion.com/restructuring-to-a-vertical-slice-architecture/ * https://www.youtube.com/watch?v=ZA2X1gaAhJk

leowest•4mo ago

Vertical Slice Architecture

DaClownieOP•4mo ago

gotcha, I'll add that to my reading list

leowest•4mo ago

so instead of having Models, ViewModels, Services yada yada

DaClownieOP•4mo ago

TermModel, TermViewModel, TermService, TermPage something like that?

leowest•4mo ago

no anyway dont worry about that right now you dont need to append Model to your models

DaClownieOP•4mo ago

haha ok

leowest•4mo ago

u would append DTO to your dtos

DaClownieOP•4mo ago

$dto no? worth a shot

leowest•4mo ago

:when:

DaClownieOP•4mo ago

:kek:

leowest•4mo ago

DTOs are used to transport only the data u need so you're not always querying your whole table and also to improve security of EF when using tracking for example

DaClownieOP•4mo ago

I've got such a long way to go :kek: Ok, I need to tackle a few things here at work, and then I'm going to dig into everything we covered

leowest•4mo ago

if I have a dashboard page and all I need there for the user is the username id and email then I can do something like model

public class User
{
    public int Id {get;set;}
    public required string Username {get;set;}
    public required string Email {get;set;}
    public int Age {get;set;}
    public string Biography {get;set;}
    // .. lots of other props ..
}

public class User
{
    public int Id {get;set;}
    public required string Username {get;set;}
    public required string Email {get;set;}
    public int Age {get;set;}
    public string Biography {get;set;}
    // .. lots of other props ..
}

Then I need Username, Email and Id

public class UserDto
{
    public int Id {get;set;}
    public string Name {get;set;}
    public string Email {get;set;}
}

public class UserDto
{
    public int Id {get;set;}
    public string Name {get;set;}
    public string Email {get;set;}
}

Then in some service I would have something like

public class UserService
{
    private readonly DatabaseContext _db;
    public UserService(DatabaseContext db)
    {
        _db = db;
    }

    public async Task<UserDto> GetUser(int id)
    {
        return await _db.Users
                        .Select(x => x.ToUserDto())
                        .FirstOrDefaultAsync(u => u.Id == id);
    }
}

public class UserService
{
    private readonly DatabaseContext _db;
    public UserService(DatabaseContext db)
    {
        _db = db;
    }

    public async Task<UserDto> GetUser(int id)
    {
        return await _db.Users
                        .Select(x => x.ToUserDto())
                        .FirstOrDefaultAsync(u => u.Id == id);
    }
}

Then in your ViewModel it would look somewhat

public class DashboardViewModel : BaseViewModel
{
    private readonly UserService _userService;
    public DashboardViewModel(UserService userService)
    {
        _userService = userService
    }

    [ObservableProperty]
    private UserDto _currentUser;

    public async Task OnLoad()
    {
        CurrentUser = await _userService.GetUser(1);
    }
}

public class DashboardViewModel : BaseViewModel
{
    private readonly UserService _userService;
    public DashboardViewModel(UserService userService)
    {
        _userService = userService
    }

    [ObservableProperty]
    private UserDto _currentUser;

    public async Task OnLoad()
    {
        CurrentUser = await _userService.GetUser(1);
    }
}

and subsequently that generates a SQL query like

SELECT id, username, email FROM users WHERE id = 1

SELECT id, username, email FROM users WHERE id = 1

instead of:

SELECT * FROM users WHERE id = 1

SELECT * FROM users WHERE id = 1

Which is more performant if u have lots of columns https://learn.microsoft.com/en-us/ef/core/performance/efficient-querying#project-only-properties-you-need so imagine u are serving the whole User to your view, now if I edit your app memory for Role and change it to Admin, and update my user I gain admin access because you're passing User around and its being tracked by EF. so that is one of the security issues DTOs tackle if your models were all readonly for example it wouldn't be an issue this is more common in webapis thou anyway hf I g2g

DaClownieOP•4mo ago

Thanks for everything! I’ll read up on all of this tonight Ok, I've been able to incorporate basically everything you've said except for this ContentPage_Loaded method. Not quite sure how to handle that yet. But I've eliminated SQLFunctions and DataObjects entirely. No more globally referenced static things laying around. Everything is through DI

leowest•4mo ago

add that to your content page then click the red squiggle and see what options it gives u

DaClownieOP•4mo ago

wants me to just create a method in TermsViewModel for OnLoaded

leowest•4mo ago

:Ok:

DaClownieOP•4mo ago

Is that where I'd plug in the code to populate the Terms list?

leowest•4mo ago

yes in the vm method which u can make async Task

DaClownieOP•4mo ago

k lemme sort out all the stuff happening It doesn't want me to assign Terms a value in a static method, and I need to convert the List<Term> to ObservableCollection which I had done before I believe, just need to look through my code somewhere :kek: Ok so my TermService has this:

public class TermService(LibrandriaDbContext context, UserService userService)
{
    public Term? CurrentTerm { get; set; }
    public async Task<List<Term>> GetTermList()
    {
        return await context.Terms
            .Where(t => t.UserId == userService.CurrentUser!.IdText).ToListAsync();
    }
...

public class TermService(LibrandriaDbContext context, UserService userService)
{
    public Term? CurrentTerm { get; set; }
    public async Task<List<Term>> GetTermList()
    {
        return await context.Terms
            .Where(t => t.UserId == userService.CurrentUser!.IdText).ToListAsync();
    }
...

TermsPage.xaml.cs has:

    public TermsViewModel TermsViewModel => (TermsViewModel)BindingContext;
    public TermsPage(TermsViewModel vm)
    {
        InitializeComponent();
        BindingContext = vm;
    }

    private async void ContentPage_Loaded(object sender, EventArgs e)
    {
        await TermsViewModel.OnLoaded();
    }

    public TermsViewModel TermsViewModel => (TermsViewModel)BindingContext;
    public TermsPage(TermsViewModel vm)
    {
        InitializeComponent();
        BindingContext = vm;
    }

    private async void ContentPage_Loaded(object sender, EventArgs e)
    {
        await TermsViewModel.OnLoaded();
    }

TermsViewModel has:

public partial class TermsViewModel(TermService termService) : BaseViewModel
{
    public ObservableCollection<Term> Terms { get; set; }

    public static async Task OnLoaded()
    {
        var term = await termService.GetTermList();
    }
}

public partial class TermsViewModel(TermService termService) : BaseViewModel
{
    public ObservableCollection<Term> Terms { get; set; }

    public static async Task OnLoaded()
    {
        var term = await termService.GetTermList();
    }
}

It says I can't use the primary constructor termService in that context, but then if I change it to TermService.GetTermList(); it says I can't access the static method of GetTermList(), but if I make GetTermList() static, it won't allow me to use my context from my constructor there I'm going in a loop :kek: Ok... so I had to move

(TermService termService) out of the primary constructor and make this:
```cs
public partial class TermsViewModel : BaseViewModel
{
    private static TermService _termService;
    public TermsViewModel(TermService termService)
    {
        _termService = termService;
    }

    public static async Task OnLoaded()
    {
        var term = await _termService.GetTermList();
        Terms = new ObservableCollection<Term>(term);
    }
```
Now everything seems to be happy?
I can probably remove the whole var term thing there and make that a single line, lets see if it populates my terms first
Where do I actually call the

ContentPage_Loaded` method, and what am I using for the sender and args when I do?

leowest•4mo ago

I mean the code is very clear where it is at, you can see TermsPage and u also know what a ContentPage is also why the heck are u using static everywhere dont there is no code that needs static in anything I showed u earlier stop recurring to static for everything its bad

DaClownieOP•4mo ago

I couldn’t call the TermsViewModel.OnLoaded. Rider threw an error because it wasn’t a static method in the VM

leowest•4mo ago

no it threw an error because u did not write it like in my example also I admit the naming was ambiguous there should have made it simpler with

private readonly TermsViewModel _termsViewModel;

public TermsPage(TermsViewModel vm)
{
    _termsViewModel = vm;
    InitializeComponent();
    BindingContext = _termsViewModel;
}

private readonly TermsViewModel _termsViewModel;

public TermsPage(TermsViewModel vm)
{
    _termsViewModel = vm;
    InitializeComponent();
    BindingContext = _termsViewModel;
}

so u would call _termsViewModel.OnLoaded(); as it was with the ambiguous name u would probably have to use this.TermsViewModel so it understand it was referring to the instance of TermsViewModel and not the actual type

DaClownieOP•4mo ago

Ok, I’m about to drive home but I’ll take a quick stab at it before I go to bed and see if I can’t get it working like we want I should have noticed from the color coding from your visual studio screenshot

leowest•4mo ago

no worries I did make it confusing by naming it the same as the type

DaClownieOP•4mo ago

I’ve been up close to 24 hours :kekw:

leowest•4mo ago

either way excluding the statics it all looks fine

DaClownieOP•4mo ago

Very cool, greatly appreciated Been taking a lot of time to read docs and things to understand the guidance better. Don’t wanna just copy it and not understand what it’s doing

leowest•4mo ago

just side note I wouldn't make this a dependency

public class TermService(LibrandriaDbContext context, UserService userService)
{
    public Term? CurrentTerm { get; set; }
    public async Task<List<Term>> GetTermList()
    {
        return await context.Terms
            .Where(t => t.UserId == userService.CurrentUser!.IdText).ToListAsync();
    }

public class TermService(LibrandriaDbContext context, UserService userService)
{
    public Term? CurrentTerm { get; set; }
    public async Task<List<Term>> GetTermList()
    {
        return await context.Terms
            .Where(t => t.UserId == userService.CurrentUser!.IdText).ToListAsync();
    }

if all u need to pass in is an id I would rather pass the id and decouple it GetTermsByUser(int id) or ForUser(int id) or w/e the type it is it makes more sense understandable, and yes its very good that you're taking that time on top of practicing and doing it makes it click faster

DaClownieOP•4mo ago

Ok, I got everything working Interestingly enough I could not get my interface to update unless I changed back to this:

    [ObservableProperty] 
    private ObservableCollection<Term> _terms;

    [ObservableProperty] 
    private ObservableCollection<Term> _terms;

I know you had mentioned that it was already Observable and not necessary, but I went through all of the breakpoints, saw that the method was being called, the list was being populated, the list was being passed to the ObservableCollection<Term> Terms but it just wasn't drawing on the UI. For shits and giggles I went back to this just to see if it changed anything (thinking it wouldn't, but eliminating all things) and it worked.

leowest•4mo ago

if it was not updating something was wrong because I can 100% guarantee you that does not need it that is the one type that doesnt need it

DaClownieOP•4mo ago

Yea the only change I made to make everything display was add [ObservableProperty]. Weird right? lol My next issue is handling popups, but my google searches are showing that it might in fact be a bug in MAUI with iOS/MacOS, otherwise though I'm cruising along at the moment Got that resolved now a well forging along. If I get to the end and have time, i'll dig into the observable property on the collection issue, but not a big deal atm

leowest•4mo ago

$close

MODiX•4mo ago

If you have no further questions, please use /close to mark the forum thread as answered

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✅ How to access specific fields from an [ObservableProperty] ObservableCollection<Object>?