bwfc-data-migration

Web Forms Data Access & Architecture Migration

Overview

Covers data access and architecture migration — the Layer 2/3 decisions requiring project-specific judgment.

Related: /bwfc-migration (markup), /bwfc-identity-migration (auth)

When to Use This Skill

• Convert SelectMethod string → SelectHandler delegate, replace DataSource controls with service injection
• Migrate Entity Framework 6 → EF Core
• Convert Session/ViewState/Application state to Blazor patterns
• Migrate Global.asax → Program.cs, Web.config → appsettings.json
• Replace HTTP Handlers/Modules with middleware

Critical Rules

Session State Migration

Use SessionShim (Default — Works Everywhere)

Pages inheriting WebFormsPageBase get a Session property backed by SessionShim. SessionShim works in BOTH SSR and interactive modes:

• SSR: Reads/writes to ASP.NET Core ISession (cookie-backed)
• Interactive: Uses in-memory ConcurrentDictionary scoped per circuit

Original Web Forms:

Session["CartId"] = Guid.NewGuid().ToString();
var cartId = Session["CartId"].ToString();
Session["payment_amt"] = 99.99m;

Migrated Blazor (IDENTICAL):

Session["CartId"] = Guid.NewGuid().ToString();
var cartId = Session["CartId"].ToString();
Session["payment_amt"] = 99.99m;

No IHttpContextAccessor. No Minimal API. No cookies. Just Session["key"].

For non-page components, inject SessionShim directly:

@inject SessionShim Session

@code {
    protected override void OnInitialized()
    {
        var userId = Session["UserId"]?.ToString() ?? "guest";
    }
}

When to Upgrade Beyond SessionShim

Only consider alternatives when you need cross-tab or cross-server persistence:

ProtectedBrowserStorage — For data that must survive page refreshes:

@inject ProtectedSessionStorage SessionStorage

protected override async Task OnAfterRenderAsync(bool firstRender)
{
    if (firstRender)
    {
        var result = await SessionStorage.GetAsync<ShoppingCart>("cart");
        cart = result.Success ? result.Value! : new ShoppingCart();
    }
}