Entity Framework Core

What it does

When your agent uses it

• Model configuration
• EF6 migration decisions
• : unrelated stacks
• Generic tasks that do not need this specific guidance

Example prompts

• “/entity-framework-core”

Requirements

• Compatibility (from SKILL.md): Requires EF Core 7+ (preferably 8/9 for latest features).

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

1. 1Prefer EF Core for new development unless a documented gap requires Dapper or raw SQL
2. 2Keep DbContext lifetime scoped — align with unit of work
3. 3Review query translation — check generated SQL, avoid N+1
4. 4Treat migrations as first-class — reviewable, not throwaway
5. 5Be deliberate about provider behavior — cross-provider but not identical
6. 6Validate with query inspection — not just in-memory mental model

What it can do on your machine

Read from SKILL.md and the folder at commit 535dd55. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • dotnet

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • learn.microsoft.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Requires EF Core 7+ (preferably 8/9 for latest features).

  From compatibility in the SKILL.md frontmatter.

Context cost

Entity Framework Core loads about 2.3k tokens when it runs, and up to ~7.8k if it reads all its reference files. Until then it costs about 140 tokens; SKILL.md has 403 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~140

When it runs · the whole SKILL.md, loaded when a task matches

~2.3k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~7.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from managedcode/dotnet-skills at commit 535dd55, republished under its MIT licence (© managedcode). 403 words, ~2,307 tokens.

name

entity-framework-core

description

Design, tune, or review EF Core data access with proper modeling, migrations, query translation, performance, and lifetime management for modern .NET applications. USE FOR: DbContext, migrations, model configuration, EF queries, tracking, loading, performance, transactions, and EF6 migration decisions. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.

compatibility

Requires EF Core 7+ (preferably 8/9 for latest features).

public class AppDbContext : DbContext
{
    public DbSet<Product> Products => Set<Product>();
    public DbSet<Order> Orders => Set<Order>();

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

// Entity Configuration (Fluent API)
public class ProductConfiguration : IEntityTypeConfiguration<Product>
{
    public void Configure(EntityTypeBuilder<Product> builder)
    {
        builder.HasKey(p => p.Id);
        builder.Property(p => p.Name).HasMaxLength(200).IsRequired();
        builder.HasIndex(p => p.Sku).IsUnique();
        builder.HasMany(p => p.OrderItems).WithOne(oi => oi.Product);
    }
}

builder.Services.AddDbContext<AppDbContext>(options =>
    options.UseSqlServer(connectionString)
           .EnableSensitiveDataLogging()  // Dev only
           .EnableDetailedErrors());      // Dev only

// Or with pooling (better performance)
builder.Services.AddDbContextPool<AppDbContext>(options =>
    options.UseSqlServer(connectionString));

// Bad - tracks entities unnecessarily
var products = await db.Products.ToListAsync();

// Good - no tracking overhead
var products = await db.Products
    .AsNoTracking()
    .ToListAsync();

// Bad - loads entire entity graph
var orders = await db.Orders
    .Include(o => o.Items)
    .Include(o => o.Customer)
    .ToListAsync();

// Good - loads only needed data
var orders = await db.Orders
    .Select(o => new OrderDto
    {
        Id = o.Id,
        CustomerName = o.Customer.Name,
        ItemCount = o.Items.Count,
        Total = o.Items.Sum(i => i.Price)
    })
    .ToListAsync();

// Bad - N+1 problem
foreach (var order in orders)
{
    var items = await db.OrderItems
        .Where(i => i.OrderId == order.Id)
        .ToListAsync();
}

// Good - eager loading
var orders = await db.Orders
    .Include(o => o.Items)
    .ToListAsync();

// Good - split query for large graphs
var orders = await db.Orders
    .Include(o => o.Items)
    .AsSplitQuery()
    .ToListAsync();

// Pre-compiled for frequently used queries
private static readonly Func<AppDbContext, int, Task<Product?>> GetProductById =
    EF.CompileAsyncQuery((AppDbContext db, int id) =>
        db.Products.FirstOrDefault(p => p.Id == id));

// Usage
var product = await GetProductById(db, productId);

# Add migration
dotnet ef migrations add AddProductIndex

# Apply to database
dotnet ef database update

# Generate SQL script
dotnet ef migrations script --idempotent -o migrate.sql

public partial class AddProductIndex : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.CreateIndex(
            name: "IX_Products_Sku",
            table: "Products",
            column: "Sku",
            unique: true);

        // Data migration (if needed)
        migrationBuilder.Sql(@"
            UPDATE Products
            SET NormalizedName = UPPER(Name)
            WHERE NormalizedName IS NULL");
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropIndex(
            name: "IX_Products_Sku",
            table: "Products");
    }
}

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }

    [ConcurrencyCheck]
    public int Version { get; set; }

    // Or use RowVersion
    [Timestamp]
    public byte[] RowVersion { get; set; }
}

// Handle concurrency conflicts
try
{
    await db.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException ex)
{
    var entry = ex.Entries.Single();
    var databaseValues = await entry.GetDatabaseValuesAsync();
    // Resolve conflict...
}

© managedcode, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files (references) in catalog/Frameworks/Entity-Framework-Core/skills/entity-framework-core of managedcode/dotnet-skills.

• SKILL.md
• manifest.json
• references/anti-patterns.md
• references/patterns.md

Open the folder on GitHubat commit 535dd55