Question
I'm working on an MVC project using the repository pattern and entity framework; right now, a sample model is shown on my form.
SampleModel
1) name
2) age
3) Identify
4) notes
5) Updated date
On the edit form, I am simply showing the data below.
1) name
2) age
3) Identify
Now, if I use the repository to update the model with missing property values, the notes, dateupdated field becomes null.
My concern is how to use the repository to update just a few chosen properties (tryupdatemodel is not included in the repository). I do not want to call the original object and map the properties to the updated model.
There must be a way, somewhere.
Accepted Answer
You may only change a portion of the fields:
using (var context = new YourDbContext())
{
context.SamepleModels.Attach(sampleModel);
DbEntityEntry<SameplModel> entry = context.Entry(sampleModel);
entry.Property(e => e.Name).IsModified = true;
entry.Property(e => e.Age).IsModified = true;
entry.Property(e => e.Address).IsModified = true;
context.SaveChanges();
}
or using the ObjectContext API
using (var context = new YourObjectContext())
{
context.SamepleModels.Attach(sampleModel);
ObjectStateEntry entry = context.ObjectStateManager.GetObjectStateEntry(sampleModel);
entry.SetModifiedProperty("Name");
entry.SetModifiedProperty("Age");
entry.SetModifiedProperty("Address");
context.SaveChanges();
}
Popular Answer
This post is old, but if anybody is interested, we've developed a useful extension technique for EF 4.1 and newer to build on Ladislav's solutions:
public static void SetModified<TEntity>(
this DbEntityEntry<TEntity> entry,
IEnumerable<Expression<Func<TEntity, object>>> expressions) where TEntity : class, IEntity
{
foreach (var expression in expressions)
entry.Property(expression).IsModified = true;
}
Unless you're using an interface with the same name for your POCOs, you'll need to remove the IEntity constraint.
Usage examples include:
var user = new User
{
Id = Request.Id,
UserName = Request.UserName,
FirstName = Request.FirstName
};
var expressions = new List<Expression<Func<User, object>>>
{
x => x.UserName,
x => x.FirstName
};
context.Entry(user).SetModified(expressions);
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