10 Entity Framework Core Best Practices

Entity Framework Core is a powerful tool for data access in .NET applications. When used correctly, it can help you write cleaner and more maintainable code. However, when used incorrectly, it can lead to performance issues and code that is difficult to debug and maintain.

In this article, we will discuss 10 best practices for working with Entity Framework Core. By following these best practices, you can avoid common pitfalls and make the most of this powerful tool.

1. Use the Latest Version of Entity Framework Core

The latest version will have the most up-to-date features, bug fixes, and performance improvements. Additionally, the community around Entity Framework Core is very active, and new versions are released frequently.

If you’re using an older version of Entity Framework Core, you may be missing out on important features or security fixes. Therefore, it’s always a good idea to upgrade to the latest version as soon as possible.

2. Avoid Using DbContext Pooling in ASP.NET Core Applications

When an ASP.NET Core application starts up, it creates a pool of DbContext instances. These instances are then used to service requests from web pages and web APIs. The problem with this approach is that it can lead to memory leaks, as the DbContext instances are never disposed of properly.

A better approach is to create a new DbContext instance for each request, and then dispose of it when the request is complete. This ensures that there are no leaked DbContext instances, and that all resources are properly disposed of.

3. Don’t Ignore Warnings About Sensitive Data

When Entity Framework Core maps data from your database to your entity classes, it automatically detects whether or not the data is sensitive. If the data is deemed sensitive, Entity Framework Core will generate a warning.

The reason you should pay attention to these warnings is because sensitive data could potentially be leaked if your entity classes are serialized and sent over the network without encryption. By default, Entity Framework Core will serialize all entity properties, even if they’re marked as private.

To avoid this, you need to explicitly specify which entity properties should be serialized using the [JsonProperty] attribute. For example:

[JsonProperty(nameof(Name))]
public string Name { get; set; }

[JsonProperty(nameof(CreditCardNumber))]
public string CreditCardNumber { get; set; }

By doing this, you can ensure that only the entity properties you want to be serialized are actually serialized. This is especially important for sensitive data, such as credit card numbers and passwords.

4. Use AsNoTracking() to Improve Performance

When querying data from a database, Entity Framework will by default keep track of the entities it retrieves in what’s called its “change tracker”. This is useful if you want to make changes to those entities and then save those changes back to the database. However, if you’re just querying data and not making any changes, there’s no need to keep track of the entities, and this tracking can actually have a negative impact on performance.

That’s where AsNoTracking() comes in. By calling AsNoTracking() on a query, you’re telling Entity Framework not to keep track of the entities it retrieves. This can lead to a significant performance boost, especially when retrieving large amounts of data.

Of course, there are some trade-offs to consider. Without change tracking, you won’t be able to update or delete entities that you retrieve from the database. So, if you need to make changes to the data, you’ll need to call AsNoTracking() on a separate query.

Overall, though, the performance benefits of using AsNoTracking() outweigh the drawbacks, and it’s definitely something you should consider using in your own applications.

5. Use Lazy Loading Sparingly

Lazy Loading is the process of deferring the loading of related entities until they are actually needed. For example, when querying for a blog post, you might not want to load all of the comments related to that post right away. Lazy Loading allows you to do just that by deferring the loading of those related entities until they are explicitly requested.

While this might sound like a good idea at first, there are some drawbacks to using Lazy Loading. The biggest one is that it can lead to performance issues if not used carefully.

The reason for this is that when you lazy load related entities, EF Core has to go back to the database to query for those related entities every time they are accessed. This can quickly add up and lead to unnecessary roundtrips to the database.

It’s important to note that Lazy Loading is different from Eager Loading, which is the process of eagerly loading related entities when querying for an entity. With Eager Loading, EF Core will query for both the entity and its related entities in a single trip to the database, which can help improve performance.

So, as a general rule of thumb, you should only use Lazy Loading if you’re absolutely sure that you need it and you know what you’re doing. If you’re not sure, then it’s probably best to stick with Eager Loading.

6. Use Explicit Loading When You Need It

When you query for data using Entity Framework Core, the default behavior is lazy loading. This means that related data is not retrieved from the database until you specifically tell EF Core to do so.

While this may not seem like a big deal, it can actually have a significant impact on performance. Lazy loading can cause EF Core to generate a lot of unnecessary SQL queries, which can lead to decreased performance and increased resource usage.

Explicit loading, on the other hand, allows you to explicitly specify which related data should be loaded along with the main entity. This can help improve performance by reducing the number of SQL queries that EF Core generates.

It’s important to note that explicit loading is not always the best choice. In some cases, lazy loading may actually be more efficient. For example, if you only need to access a small amount of related data, it may be more efficient to lazy load it since EF Core will only generate the necessary SQL queries when you actually try to access the data.

As a general rule, you should use explicit loading whenever possible. Only use lazy loading when you have a specific reason to do so.

7. Be Careful With Change Tracking Proxies

Change tracking proxies are classes that inherit from your entity classes and are used by Entity Framework to keep track of changes made to entities. These proxies are created automatically when you query for entities using the DbContext.

The problem with these proxies is that they can cause unexpected behavior in your application if you’re not careful. For example, let’s say you have a Customer entity with a navigation property to their Orders. If you query for Customers and then iterate over the Orders navigation property, each Order will be a change tracking proxy.

If you make any changes to an Order and then save those changes back to the database using the DbContext, those changes will be saved, even if you didn’t explicitly call the DbContext.SaveChanges method.

This can lead to data loss if you’re not careful, so it’s important to understand how change tracking proxies work and how to use them correctly.

8. Use Value Conversions for Better Performance and Simpler Queries

Value conversions allow you to store data in the database in a format that is different from how it is represented in your entity classes. For example, you could store dates as integers in the database, but still have them appear as DateTime objects in your entity class.

Value conversions can improve performance because they can reduce the amount of data that needs to be retrieved from the database. They can also simplify queries by allowing you to filter and sort data in the database without having to convert it first.

To use value conversions in Entity Framework Core, you need to create a value converter class and then register it with your model. You can then annotate your properties with the [ValueConversion] attribute to specify which converter should be used.

9. Use Raw SQL Queries When Necessary

Entity Framework Core is an ORM (object-relational mapper) that enables developers to work with relational data using domain-specific objects. However, there are times when working with raw SQL queries is more efficient than using the Entity Framework Core ORM.

For example, if you need to execute a complex query that can’t be easily expressed using LINQ, or if you need to optimize performance by taking advantage of database-specific features, then using a raw SQL query may be your best option.

When working with raw SQL queries, it’s important to use parameterized queries to protect against SQL injection attacks. Parameterized queries allow you to specify the parameters for a query without concatenating strings, which can leave your application vulnerable to attack.

To use a raw SQL query in Entity Framework Core, you can use the Database.ExecuteSqlCommand() method. This method takes two parameters: the SQL query and the parameters for the query. The parameters for the query are specified as an array of anonymous types.

Here’s an example of how to use the Database.ExecuteSqlCommand() method to execute a raw SQL query:

var sql = “UPDATE products SET price = @price WHERE id = @id”;

var parameters = new[] {
new { price = 100, id = 1 },
new { price = 200, id = 2 }
};

context.Database.ExecuteSqlCommand(sql, parameters);

10. Use Migrations for Database Changes

Migrations allow you to keep track of changes made to your database schema, and they make it easy to apply those changes to other databases. For example, if you make a change to your development database and then want to apply that change to your production database, you can simply run the Migration on the production database to update it.

This is a much better approach than manually making changes to your database, or relying on scripts that may not work correctly. Migrations also make it easy to roll back changes if necessary.

To use Migrations, simply add a new Migration file to your project whenever you make a change to your database. Then, when you’re ready to apply the changes, you can use the ‘ef database update’ command to update your database.