efcore-patterns

Name: efcore-patterns
Author: Aaronontheweb

1.2kinstalls98forks

How to install efcore-patterns?

aaronontheweb/dotnet-skills/efcore-patterns

$npx -y skills add Aaronontheweb/dotnet-skills --skill efcore-patterns

Installs into the current project.

Summary

Entity Framework Core best practices including NoTracking by default, query splitting for navigation collections, migration management, dedicated migration services, and common pitfalls to avoid.

Files · 1

View on GitHub

SKILL.md

1	# Entity Framework Core Patterns
2
3	## When to Use This Skill
4
5	Use this skill when:
6	- Setting up EF Core in a new project
7	- Optimizing query performance
8	- Managing database migrations
9	- Integrating EF Core with .NET Aspire
10	- Debugging change tracking issues
11	- Loading multiple navigation collections efficiently (query splitting)
12
13	## Core Principles
14
15	1. NoTracking by Default - Most queries are read-only; opt-in to tracking
16	2. Never Edit Migrations Manually - Always use CLI commands
17	3. Dedicated Migration Service - Separate migration execution from application startup
18	4. ExecutionStrategy for Retries - Handle transient database failures
19	5. Explicit Updates - When NoTracking, explicitly mark entities for update
20
21	---
22
23	## Pattern 1: NoTracking by Default
24
25	Configure your DbContext to disable change tracking by default. This improves performance for read-heavy workloads.
26
27	```csharp
28	public class ApplicationDbContext : DbContext
29	{
30	public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
31	: base(options)
32	{
33	// Disable change tracking by default for better performance on read-only queries
34	// Use .AsTracking() explicitly for queries that need to track changes
35	ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;
36	}
37
38	public DbSet<Order> Orders => Set<Order>();
39	public DbSet<Customer> Customers => Set<Customer>();
40	}
41	```
42
43	### When NoTracking is Active
44
45	Read-only queries work normally:
46	```csharp
47	// ✅ Fast read - no tracking overhead
48	var orders = await dbContext.Orders
49	.Where(o => o.Status == OrderStatus.Pending)
50	.ToListAsync();
51	```
52
53	Writes require explicit handling:
54	```csharp
55	// ❌ WRONG - Entity not tracked, SaveChanges does nothing
56	var order = await dbContext.Orders.FirstOrDefaultAsync(o => o.Id == orderId);
57	order.Status = OrderStatus.Shipped;
58	await dbContext.SaveChangesAsync(); // Nothing happens!
59
60	// ✅ CORRECT - Explicitly mark entity for update
61	var order = await dbContext.Orders.FirstOrDefaultAsync(o => o.Id == orderId);
62	order.Status = OrderStatus.Shipped;
63	dbContext.Orders.Update(order); // Marks entire entity as modified
64	await dbContext.SaveChangesAsync();
65
66	// ✅ ALSO CORRECT - Use AsTracking() for the query
67	var order = await dbContext.Orders
68	.AsTracking()
69	.FirstOrDefaultAsync(o => o.Id == orderId);
70	order.Status = OrderStatus.Shipped;
71	await dbContext.SaveChangesAsync(); // Works!
72	```
73
74	### When to Use Tracking
75
76	\| Scenario \| Use Tracking? \| Why \|
77	\|----------\|---------------\|-----\|
78	\| Display data in UI \| No \| Read-only, no updates \|
79	\| API GET endpoints \| No \| Returning data, no mutations \|
80	\| Update single entity \| Yes or explicit Update() \| Need to save changes \|
81	\| Complex update with navigation \| Yes \| Tracking handles relationships \|
82	\| Batch operations \| No + ExecuteUpdate \| More efficient \|
83
84	### Explicit Add/Update Pattern
85
86	```csharp
87	public class OrderService
88	{
89	private readonly ApplicationDbContext _db;
90
91	// CREATE - Always use Add (works regardless of tracking)
92	public async Task<Order> CreateOrderAsync(Order order)
93	{
94	_db.Orders.Add(order);
95	await _db.SaveChangesAsync();
96	return order;
97	}
98
99	// UPDATE - Explicitly mark as modified
100	public async Task UpdateOrderStatusAsync(Guid orderId, OrderStatus newStatus)
101	{
102	var order = await _db.Orders.FirstOrDefaultAsync(o => o.Id == orderId)
103	?? throw new NotFoundException($"Order {orderId} not found");
104
105	order.Status = newStatus;
106	order.UpdatedAt = DateTimeOffset.UtcNow;
107
108	// Explicitly mark as modified since DbContext uses NoTracking by default
109	_db.Orders.Update(order);
110	await _db.SaveChangesAsync();
111	}
112
113	// DELETE - Attach and remove
114	public async Task DeleteOrderAsync(Guid orderId)
115	{
116	var order = new Order { Id = orderId };
117	_db.Orders.Remove(order);
118	await _db.SaveChangesAsync();
119	}
120	}
121	```
122
123	---
124
125	## Pattern 2: Never Edit Migrations Manually
126
127	CRITICAL: Always use EF Core CLI commands to manage migrations. Never:
128	- Manually edit migration files (except for custom SQL in `Up()`/`Down()`)
129	- Delete migration files directly
130	- Rename migration files
131	- Copy migrations between projects
132
133	### Creating Migrations
134
135	```bash
136	# Create a new migration
137	dotnet ef migrations add AddCustomerTable \
138	--project src/MyApp.Infrastructure \
139	--startup-project src/MyApp.Api
140
141	# With a specific DbContext (if you have multiple)
142	dotnet ef migrations add AddCustomerTable \
143	--context ApplicationDbContext \
144	--project src/MyApp.Infrastructure \
145	--startup-project src/MyApp.Api
146	```
147
148	### Removing Migrations
149
150	```bash
151	# Remove the last migration (if not yet applied)
152	dotnet ef migra

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6 picks

Type

efcore-patterns

1.2kinstalls98forks

View on GitHub

How to install efcore-patterns?

aaronontheweb/dotnet-skills/efcore-patterns

$npx -y skills add Aaronontheweb/dotnet-skills --skill efcore-patterns

Installs into the current project.

Summary

Entity Framework Core best practices including NoTracking by default, query splitting for navigation collections, migration management, dedicated migration services, and common pitfalls to avoid.

Files · 1

View on GitHub

SKILL.md

1	# Entity Framework Core Patterns
2
3	## When to Use This Skill
4
5	Use this skill when:
6	- Setting up EF Core in a new project
7	- Optimizing query performance
8	- Managing database migrations
9	- Integrating EF Core with .NET Aspire
10	- Debugging change tracking issues
11	- Loading multiple navigation collections efficiently (query splitting)
12
13	## Core Principles
14
15	1. NoTracking by Default - Most queries are read-only; opt-in to tracking
16	2. Never Edit Migrations Manually - Always use CLI commands
17	3. Dedicated Migration Service - Separate migration execution from application startup
18	4. ExecutionStrategy for Retries - Handle transient database failures
19	5. Explicit Updates - When NoTracking, explicitly mark entities for update
20
21	---
22
23	## Pattern 1: NoTracking by Default
24
25	Configure your DbContext to disable change tracking by default. This improves performance for read-heavy workloads.
26
27	```csharp
28	public class ApplicationDbContext : DbContext
29	{
30	public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
31	: base(options)
32	{
33	// Disable change tracking by default for better performance on read-only queries
34	// Use .AsTracking() explicitly for queries that need to track changes
35	ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;
36	}
37
38	public DbSet<Order> Orders => Set<Order>();
39	public DbSet<Customer> Customers => Set<Customer>();
40	}
41	```
42
43	### When NoTracking is Active
44
45	Read-only queries work normally:
46	```csharp
47	// ✅ Fast read - no tracking overhead
48	var orders = await dbContext.Orders
49	.Where(o => o.Status == OrderStatus.Pending)
50	.ToListAsync();
51	```
52
53	Writes require explicit handling:
54	```csharp
55	// ❌ WRONG - Entity not tracked, SaveChanges does nothing
56	var order = await dbContext.Orders.FirstOrDefaultAsync(o => o.Id == orderId);
57	order.Status = OrderStatus.Shipped;
58	await dbContext.SaveChangesAsync(); // Nothing happens!
59
60	// ✅ CORRECT - Explicitly mark entity for update
61	var order = await dbContext.Orders.FirstOrDefaultAsync(o => o.Id == orderId);
62	order.Status = OrderStatus.Shipped;
63	dbContext.Orders.Update(order); // Marks entire entity as modified
64	await dbContext.SaveChangesAsync();
65
66	// ✅ ALSO CORRECT - Use AsTracking() for the query
67	var order = await dbContext.Orders
68	.AsTracking()
69	.FirstOrDefaultAsync(o => o.Id == orderId);
70	order.Status = OrderStatus.Shipped;
71	await dbContext.SaveChangesAsync(); // Works!
72	```
73
74	### When to Use Tracking
75
76	\| Scenario \| Use Tracking? \| Why \|
77	\|----------\|---------------\|-----\|
78	\| Display data in UI \| No \| Read-only, no updates \|
79	\| API GET endpoints \| No \| Returning data, no mutations \|
80	\| Update single entity \| Yes or explicit Update() \| Need to save changes \|
81	\| Complex update with navigation \| Yes \| Tracking handles relationships \|
82	\| Batch operations \| No + ExecuteUpdate \| More efficient \|
83
84	### Explicit Add/Update Pattern
85
86	```csharp
87	public class OrderService
88	{
89	private readonly ApplicationDbContext _db;
90
91	// CREATE - Always use Add (works regardless of tracking)
92	public async Task<Order> CreateOrderAsync(Order order)
93	{
94	_db.Orders.Add(order);
95	await _db.SaveChangesAsync();
96	return order;
97	}
98
99	// UPDATE - Explicitly mark as modified
100	public async Task UpdateOrderStatusAsync(Guid orderId, OrderStatus newStatus)
101	{
102	var order = await _db.Orders.FirstOrDefaultAsync(o => o.Id == orderId)
103	?? throw new NotFoundException($"Order {orderId} not found");
104
105	order.Status = newStatus;
106	order.UpdatedAt = DateTimeOffset.UtcNow;
107
108	// Explicitly mark as modified since DbContext uses NoTracking by default
109	_db.Orders.Update(order);
110	await _db.SaveChangesAsync();
111	}
112
113	// DELETE - Attach and remove
114	public async Task DeleteOrderAsync(Guid orderId)
115	{
116	var order = new Order { Id = orderId };
117	_db.Orders.Remove(order);
118	await _db.SaveChangesAsync();
119	}
120	}
121	```
122
123	---
124
125	## Pattern 2: Never Edit Migrations Manually
126
127	CRITICAL: Always use EF Core CLI commands to manage migrations. Never:
128	- Manually edit migration files (except for custom SQL in `Up()`/`Down()`)
129	- Delete migration files directly
130	- Rename migration files
131	- Copy migrations between projects
132
133	### Creating Migrations
134
135	```bash
136	# Create a new migration
137	dotnet ef migrations add AddCustomerTable \
138	--project src/MyApp.Infrastructure \
139	--startup-project src/MyApp.Api
140
141	# With a specific DbContext (if you have multiple)
142	dotnet ef migrations add AddCustomerTable \
143	--context ApplicationDbContext \
144	--project src/MyApp.Infrastructure \
145	--startup-project src/MyApp.Api
146	```
147
148	### Removing Migrations
149
150	```bash
151	# Remove the last migration (if not yet applied)
152	dotnet ef migra

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Type