Data Update in Entity Framework

In Framework, updating records is one of the most common and frequent CRUD operations when we build an application.

Updating records involves modifying the values of an entity that already exists in the database. For this, Entity Framework tracks changes in the entities being managed by the context (DbContext).

When you call the SaveChanges() method, Entity Framework generates and executes the necessary SQL statements to reflect the changes in the database.

There are several main approaches to updating entities:

• Update an object from the DbContext
• Use the Update() method

Updating an Entity from the DbContext

The most common way is simply to update one of the entities in the DbContext. For example,

using (var context = new SchoolContext())
{
    var student = context.Students.Find(1); // Search by primary key
    if (student != null)
    {
        student.Name = "New Name"; // Update the name
        student.Age = 21; // Update the age

        context.SaveChanges(); // Save changes to the database
    }
}

Updating Records with Update

The Update method is a straightforward way to mark an entity as modified.

When this method is called, Entity Framework assumes that the entity has been altered and that it should generate an SQL UPDATE statement to synchronize the changes in the database.

dbContext.Update(entity);
dbContext.SaveChanges();

Suppose we have a Product entity with the following properties:

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

To update an existing product, we first retrieve it from the database, modify its properties, and then call the Update method:

using (var dbContext = new MyDbContext())
{
    // Retrieve the product to update
    var product = dbContext.Products.Find(1); // Suppose the Id is 1

    if (product != null)
    {
        // Modify the properties
        product.Name = "New Name";
        product.Price = 99.99m;

        // Mark the entity as modified
        dbContext.Update(product);

        // Save changes to the database
        dbContext.SaveChanges();
    }
}