dotpudica-view

name	dotpudica-view
description	Create DotPudica View + ViewModel pairs with declarative bindings: [DotPudicaView], [BindTo], [BindCommand], [ItemsSource], [Inject], [Subscribe], [ViewModelFactory], lifecycle hooks and the mandatory _Ready/_ExitTree lines. Use whenever the user wants a UI page, panel, menu, list, a binding that does not work, or a property that does not update the UI.

dotpudica-view

Purpose

Build a page, panel, menu, or list as a [DotPudicaView] partial class bound to a ViewModel through declarative attributes, so UI state and commands flow automatically with zero hand-written plumbing. This is the I/O contract for page development: it defines what a valid View + ViewModel pair looks like, the exact steps to produce one, and the failure modes the source generator reports. It is the core dependency of the add-page workflow and of every fix where "a binding does not work" or "a property does not update the UI".

Input Contract

Preconditions:

• Bootstrap is done: AppContext.Initialize has completed (otherwise run dotpudica-bootstrap first). Views resolve [Inject] services from AppContext.Current.Services.
• Godot 4.7.x .NET project with the DotPudica csproj block injected (see dotpudica-bootstrap).

Valid input states:

• ViewModel = partial class deriving from ViewModelBase or ValidatableViewModelBase (DotPudica.Core.ViewModels), or any ObservableObject (e.g. CommunityToolkit.Mvvm.ComponentModel.ObservableObject).
• The ViewModel has exactly one public constructor whose parameters are all interface types (then no [ViewModelFactory] needed); any other construction shape requires a [ViewModelFactory] method — otherwise the generator reports DOTPUDICA040 / DOTPUDICA041.
• View = partial class + [DotPudicaView(typeof(TVM))], deriving from a Godot control.
• Control fields are [Export] (so the Godot editor stores the node reference) and already assigned in the scene inspector.
• Binding paths resolve statically: every intermediate path segment must be a reference type so chained INotifyPropertyChanged listening can be generated — a value-type intermediate segment reports DOTPUDICA030.

Procedure

1. Design the ViewModel state, commands, and events. See the complete example in the next code block. Checkpoints: the class is partial; state fields use [ObservableProperty], commands use [RelayCommand]; binding paths will use the generated names (Title, SaveCommand), not the field names (_title, Save) — see references/attributes.md section 4.

using CommunityToolkit.Mvvm.ComponentModel;
using DotPudica.Core.ViewModels;

public partial class SettingsViewModel : ViewModelBase
{
    [ObservableProperty]
    private string _title = "Settings";

    [ObservableProperty]
    private int _volume = 50;

    [RelayCommand]
    private void Save() { }
}

2. Write the View class with [DotPudicaView(typeof(TVM))], [Export] control fields carrying the binding attributes, and the two lifecycle lines. Complete example:

using DotPudica.Core.Binding;
using DotPudica.Core.Binding.Attributes;
using DotPudica.Godot.Views;
using Godot;

[DotPudicaView(typeof(SettingsViewModel))]
public partial class SettingsView : Control
{
    [Export, BindTo(nameof(SettingsViewModel.Title), Mode = BindingMode.OneWay)]
    private Label _title = null!;

    [Export, BindCommand(nameof(SettingsViewModel.SaveCommand))]
    private Button _saveButton = null!;

    public override void _Ready() => InitializeView();
    public override void _ExitTree() => DisposeView();

    partial void OnViewModelBound() { }
}

Checkpoint: _Ready and _ExitTree must both be declared AND call their entry points — Godot only dispatches overrides declared in user source, so missing either half reports DOTPUDICA046 (use RecycleView() instead of DisposeView() when Pooled = true; see references/lifecycle.md section 2 for the matrix). 3. In the scene inspector, assign the controls to the [Export] fields declared in step 2 (this skill only guides; it never generates .tscn files). Checkpoint: every [Export] binding field has a node assigned — an unassigned field dereferences at runtime when the binding executes. 4. Add [Subscribe] handlers and lifecycle hooks (OnViewReady, OnViewModelBound, OnViewDisposing) where the feature needs them. Checkpoint: the event path must resolve on the ViewModel and the handler signature must match the event delegate (void return, matching parameters) — otherwise DOTPUDICA042. 5. For lists, bind with [ItemsSource(path, itemScene)]; set ItemCommand to a [RelayCommand] whose parameter type equals the collection element type. Checkpoints: the collection implements INotifyCollectionChanged (use ObservableCollection<T>), else DOTPUDICA010; the ItemCommand parameter matches the element type, else DOTPUDICA036; PoolSize is only for non-virtualized targets — on VirtualizedItemsControl it errors with DOTPUDICA045. 6. Build with dotnet build and fix until zero DOTPUDICA diagnostics (look each ID up in references/diagnostics.md). Checkpoint: zero diagnostics; when the project builds with -p:EmitCompilerGeneratedFiles=true, obj/Generated also contains {Namespace}.{Class}.Bindings.g.cs with InitializeView / DisposeView and the generated binding statements.

Output Contract

Deliverable = the ViewModel file + the View file + a scene where every [Export] binding field is assigned. Acceptance:

• dotnet build passes with zero DOTPUDICA diagnostics.
• Runtime checkpoints pass: initial values display on open; command binding fires (button pressed → SaveCommand); subscriptions do not leak — switching scenes and returning must not produce repeated-subscription errors (bindings are released by DisposeView).
• Mutating an [ObservableProperty] updates the bound control without manual refresh.

Failure Handling

Symptom (typical trigger)	See references/diagnostics.md entry
Binding path typo, or Mvvm member written as field name (_title) instead of generated name (Title)	DOTPUDICA001
[BindCommand] points at a member whose type is not ICommand	DOTPUDICA005
[ItemsSource] collection is a plain List<T> / array	DOTPUDICA010
Path has a value-type intermediate segment (e.g. a struct inside a chained path)	DOTPUDICA030
Control has no usable default target property (e.g. Button, custom control not in the inference table)	DOTPUDICA031
Source and target types incompatible and no Converter given	DOTPUDICA032
Converter provided but does not implement the typed IValueConverter<TSource,TTarget>	DOTPUDICA033
Reference upcast (base → derived target) with TwoWay / OneWayToSource	DOTPUDICA034
Binding would box a value type (value type → object / interface / enum)	DOTPUDICA035
ItemCommand parameter type does not match the collection element type	DOTPUDICA036
AutoInitialize = true, no [ViewModelFactory], and the VM is abstract or its constructor is not all-interface	DOTPUDICA040
[ViewModelFactory] method violates the shape (not parameterless instance method returning the VM type)	DOTPUDICA041
[Subscribe] event path unresolved or handler signature incompatible	DOTPUDICA042
[Inject] member is read-only (readonly field / property without setter)

The table only maps triggers; the full trigger condition, verbatim message, and fix action live in references/diagnostics.md — look the ID up there.

References

• references/attributes.md — attribute parameters, defaults, BindingMode semantics, control inference table, cross-generator naming rules.
• references/lifecycle.md — InitializeView / DisposeView / RecycleView / ActivateViewModel step order, AutoInitialize x Pooled matrix, hook timing.
• references/diagnostics.md — full diagnostic table and the DOTPUDICA046 lifecycle matrix.
• Related skills: dotpudica-verify (verifying a built page end-to-end), dotpudica-di-scope (service registration and [Inject] resolution), dotpudica-route (choosing which skill a task needs); prerequisite: dotpudica-bootstrap.