[ACCEPTED]-Refresh entity instance with DbContext-ef-code-first
Accepted answer
You must use this:
public void Refresh(Document instance)
{
_ctx.Entry<Document>(instance).Reload();
}
0
The above doesn't work. Reload() method 8 does not correctly refresh the entity from 7 the database. It performs SQL select query 6 but does not build proxies for the navigational 5 properties. See the example below (I use 4 the Northwind database in SQL Server with 3 EF 5.1):
NorthwindEntities northwindEntities = new NorthwindEntities();
Product newProduct = new Product
{
ProductName = "new product",
Discontinued = false,
CategoryID = 3
};
northwindEntities.Products.Add(newProduct);
northwindEntities.SaveChanges();
// Now the product is stored in the database. Let's print its category
Console.WriteLine(newProduct.Category); // prints "null" -> navigational property not loaded
// Find the product by primary key --> returns the same object (unmodified)
// Still prints "null" (due to caching and identity resolution)
var productByPK = northwindEntities.Products.Find(newProduct.ProductID);
Console.WriteLine(productByPK.Category); // null (due to caching)
// Reloading the entity from the database doesn't help!
northwindEntities.Entry<Product>(newProduct).Reload();
Console.WriteLine(newProduct.Category); // null (reload doesn't help)
// Detach the object from the context
((IObjectContextAdapter)northwindEntities).ObjectContext.Detach(newProduct);
// Now find the product by primary key (detached entities are not cached)
var detachedProductByPK = northwindEntities.Products.Find(newProduct.ProductID);
Console.WriteLine(detachedProductByPK.Category); // works (no caching)
I may conclude that real refresh 2 / reload of EF entity can be done by Detach 1 + Find:
((IObjectContextAdapter)context).ObjectContext.Detach(entity);
entity = context.<SomeEntitySet>.Find(entity.PrimaryKey);
Nakov
Source:
stackoverflow.com
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