Question
I am working on mvc project, with repository pattern and entity framework, now on my form i have a sample model
SampleModel
1) name
2) age
3) address
4) notes
5) date updated
I am displaying only following data on the edit form
1) name
2) age
3) address
now if i update the model with missing property values using the repository, the notes, dateupdated field goes null.
My question is how do i update only few selected properties using the repository ( tryupdatemodel not available in repository ) and i dont want to call the original object and map the properites with the updated model.
Is there any way, there must be.
Accepted Answer
You can update only subset of 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 in 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 is an old thread, but if anyone is interested, to extend on Ladislav's solutions, we've come up with a helpful extension method for EF 4.1 and newer:
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;
}
Obviously you'll need to take away the IEntity constraint unless you're using an interface by the same name for your POCOs.
Example usage would be:
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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