Workspace Blazor MVVM Patterns

When to Use This Skill

Use this skill when:

• Creating Blazor pages for workspace-scoped documents
• Using ObservableDataView component for list views
• Implementing detail pages with workspace services
• Debugging "Unable to resolve service for type 'IObservableReader'" errors
• Working with reactive persistence (IObservableReader/Writer) in Blazor
• Setting up workspace document types with CRUD UI

Keywords: workspace, ObservableDataView, IObservableReader, IObservableWriter, workspace services, CascadingParameter, Blazor MVVM, workspace scoping, workspace documents

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Quick Reference

Critical Concept: Workspace Service Scoping

The Problem: IObservableReader/Writer services are workspace-scoped, not in the root DI container.

The Solution: Use CascadingParameter to get WorkspaceServices and resolve services manually.

[CascadingParameter(Name = "WorkspaceServices")]
public IServiceProvider? WorkspaceServices { get; set; }

var reader = WorkspaceServices.GetService<IObservableReader<string, BotEntity>>();

See: references/service-scoping.md for complete explanation.

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Two Primary Patterns

Pattern 1: ObservableDataView (List Views)

When: Displaying a list/grid of workspace documents with CRUD operations.

Code (~20-30 lines):

<ObservableDataView TKey="string"
                    TValue="BotEntity"
                    TValueVM="BotVM"
                    DataServiceProvider="@WorkspaceServices">
    <Columns>
        <PropertyColumn Property="x => x.Value.Name" />
    </Columns>
</ObservableDataView>

@code {
    [CascadingParameter(Name = "WorkspaceServices")]
    public IServiceProvider? WorkspaceServices { get; set; }
}

See: examples/list-view-example.razor for complete example.

Pattern 2: Manual VM Creation (Detail Views)

When: Displaying/editing a single workspace document with custom layout.

Code (~60-80 lines):

@code {
    [CascadingParameter(Name = "WorkspaceServices")]
    public IServiceProvider? WorkspaceServices { get; set; }

    private ObservableReaderWriterItemVM<string, BotEntity, BotVM>? VM { get; set; }

    protected override async Task OnParametersSetAsync()
    {
        var reader = WorkspaceServices.GetService<IObservableReader<string, BotEntity>>();
        var writer = WorkspaceServices.GetService<IObservableWriter<string, BotEntity>>();

        VM = new ObservableReaderWriterItemVM<string, BotEntity, BotVM>(reader, writer);
        VM.Id = BotId;
    }
}

See: examples/detail-view-example.razor for complete example.

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Step-by-Step Workflows

Workflow 1: Fix "Unable to Resolve Service" Error

When encountering:

InvalidOperationException: Unable to resolve service for type
'IObservableReader`2[System.String,MyEntity]'

Steps:

1. Identify the issue: Component trying to inject workspace-scoped services from root container

2. Check current pattern:

// ❌ WRONG: Tries to inject from root
@inherits ReactiveInjectableComponentBase<ObservableReaderWriterItemVM<string, BotEntity, BotVM>>

3. Fix with CascadingParameter:

// ✅ RIGHT: Get workspace services via cascading parameter
[CascadingParameter(Name = "WorkspaceServices")]
public IServiceProvider? WorkspaceServices { get; set; }

protected override async Task OnParametersSetAsync()
{
    var reader = WorkspaceServices.GetService<IObservableReader<string, BotEntity>>();
    var writer = WorkspaceServices.GetService<IObservableWriter<string, BotEntity>>();
    VM = new ObservableReaderWriterItemVM<string, BotEntity, BotVM>(reader, writer);
    VM.Id = ItemId;
}

4. Verify registration:

// In Program.cs, ensure:
services
    .AddWorkspaceChildType<BotEntity>()                    // ← Must have this!
    .AddWorkspaceDocumentService<string, BotEntity>();

For detailed explanation: Load references/service-scoping.md.

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Workflow 2: Create List Page for Workspace Documents

Goal: Display a reactive grid of workspace documents with CRUD operations.

Steps:

1. Verify entity and VM are defined:

[Alias("Bot")]
public partial class BotEntity : ReactiveObject
{
    [Reactive] private string? _name;
}

public class BotVM : KeyValueVM<string, BotEntity>
{
    public BotVM(string key, BotEntity value) : base(key, value) { }
}

2. Verify registration:

services
    .AddWorkspaceChildType<BotEntity>()
    .AddWorkspaceDocumentService<string, BotEntity>()
    .AddTransient<BotVM>();

3. Create list page using ObservableDataView:

   • Load examples/list-view-example.razor
   • Adapt for your entity type
   • Key: Set DataServiceProvider="@WorkspaceServices"

4. Customize columns as needed (PropertyColumn, TemplateColumn)

5. Add navigation to detail page:

<MudButton Href="@($"/bots/{context.Item.Key}")">Edit</MudButton>

For complete pattern details: Load references/blazor-mvvm-patterns.md.

---

Workflow 3: Create Detail Page for Workspace Document

Goal: Display/edit a single workspace document.

Steps:

1. Create page with route parameter:

@page "/bots/{BotId}"

@code {
    [Parameter]
    public string? BotId { get; set; }
}

2. Get workspace services:

@inject ILogger<Bot> Logger
@inject IServiceProvider ServiceProvider

@code {
    [CascadingParameter(Name = "WorkspaceServices")]
    public IServiceProvider? WorkspaceServices { get; set; }
}

3. Resolve reader/writer and create VM:

   • Load examples/detail-view-example.razor
   • Adapt service resolution pattern
   • Create ObservableReaderWriterItemVM

4. Bind UI to VM.Value:

<MudTextField @bind-Value="VM.Value.Name" Label="Name" />

5. Implement Save:

private async Task Save() => await VM.Write();

For complete pattern details: Load references/blazor-mvvm-patterns.md.

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Workflow 4: Add New Workspace Document Type

Goal: Add a new document type (e.g., Portfolio) to existing workspace application.

Steps:

1. Define entity:

[Alias("Portfolio")]
public partial class PortfolioEntity : ReactiveObject
{
    [Reactive] private string? _name;
    // ... other properties
}

2. Define ViewModel:

public class PortfolioVM : KeyValueVM<string, PortfolioEntity>
{
    public PortfolioVM(string key, PortfolioEntity value) : base(key, value) { }
}

3. Register:

services
    .AddWorkspaceChildType<PortfolioEntity>()
    .AddWorkspaceDocumentService<string, PortfolioEntity>()
    .AddTransient<PortfolioVM>();

4. Create pages (follow Workflow 2 and 3 above)

5. Result: Portfolios appear in workspace subdirectory Portfolios/

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Key Components Reference

ObservableDataView

Purpose: Pre-built MudDataGrid component with reactive workspace data integration.

Key Parameters:

• TKey, TValue, TValueVM - Type parameters
• DataServiceProvider - CRITICAL: Pass @WorkspaceServices here
• AllowedEditModes - EditMode.None, .Cell, .Form, .All
• ReadOnly - Enable/disable editing
• Columns - Custom column definitions

Automatic Features:

• CRUD toolbar (Add/Edit/Delete buttons)
• Reactive updates (file changes auto-refresh UI)
• VM creation (automatic via constructor)
• Sorting, filtering, grouping

ObservableReaderWriterItemVM

Purpose: ViewModel wrapper for single workspace documents.

Constructor:

public ObservableReaderWriterItemVM(
    IObservableReader<TKey, TValue> reader,
    IObservableWriter<TKey, TValue> writer)

Key Properties:

• Id - The document key (triggers load when set)
• Value - The wrapped entity (as TValueVM)
• Writer - Access to persistence

Key Methods:

• Write() - Save changes to file

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Common Pitfalls

❌ Pitfall 1: Injecting Workspace Services from Root

// ❌ WRONG
@inject IObservableReader<string, BotEntity> Reader

// ✅ RIGHT
[CascadingParameter(Name = "WorkspaceServices")]
public IServiceProvider? WorkspaceServices { get; set; }

var reader = WorkspaceServices.GetService<IObservableReader<string, BotEntity>>();

❌ Pitfall 2: Forgetting DataServiceProvider

<!-- ❌ WRONG -->
<ObservableDataView TKey="string" TValue="BotEntity" TValueVM="BotVM" />

<!-- ✅ RIGHT -->
<ObservableDataView TKey="string" TValue="BotEntity" TValueVM="BotVM"
                    DataServiceProvider="@WorkspaceServices" />

❌ Pitfall 3: Not Registering Document Type

// ❌ WRONG - Missing AddWorkspaceChildType
services.AddWorkspaceDocumentService<string, BotEntity>();

// ✅ RIGHT
services
    .AddWorkspaceChildType<BotEntity>()                    // ← MUST have this
    .AddWorkspaceDocumentService<string, BotEntity>();

---

References

Detailed documentation (load as needed):

• references/service-scoping.md - Deep dive on workspace service scoping and DI

  • Why workspace services are scoped
  • Complete registration flow
  • Troubleshooting DI errors

• references/blazor-mvvm-patterns.md - Complete Blazor MVVM pattern guide

  • ObservableDataView pattern details
  • Manual VM pattern details
  • When to use which pattern
  • Navigation between list/detail

• references/workspaces-architecture.md - Workspace architecture overview

  • What workspaces are
  • Service scoping model
  • Document type system
  • When to use workspaces

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Quick Decision Tree

Need to display workspace documents?
├─ Multiple items (list/grid)?
│  └─ Use ObservableDataView ✅
│     → See examples/list-view-example.razor
└─ Single item (detail/edit)?
   └─ Use Manual VM Pattern ✅
      → See examples/detail-view-example.razor

Getting "Unable to resolve service" error?
└─ Using @inject instead of CascadingParameter?
   └─ Fix: Use CascadingParameter for WorkspaceServices
      → See references/service-scoping.md

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Summary

This skill teaches two complementary patterns:

1. ObservableDataView - Automatic reactive grids with minimal code
2. Manual VM Creation - Full control for detail views

Both require: CascadingParameter to access workspace-scoped services.

Most Common Issue: Trying to inject workspace services from root DI container.

Solution: Always use CascadingParameter(Name = "WorkspaceServices").