I have a customer which I want to update in the repository.
var customer = new Customer{ Name = "Test" }
The customer has still more properties which are null, because I have not loaded them before to the client. Thus these properties have all their default values like null or 0.
What do I have to do with latest EF 6, that only the property Name is updated and the other properties from the customer are not overwritten?
1.) How would I have to query/update the customer?
2.) What would happen if the customer has a collection of and he has changed some properties of some meetings - but not all properties - how would then be the override behavior?
UPDATE pseudo code
Open context
Get customer
Close context
Open context
Update customer.name
SAveChanges
Close context
The custom.name is not saved, why?
You can't do it natively without getting the whole entiy first, which is obviously 2 db hits.
There is however an extension you can use that does what you want:
https://github.com/loresoft/EntityFramework.Extended/wiki/Batch-Update-and-Delete
Assuming you already have your model generated and it has a name of "MyEntities" and you should have a customer ID if you are updating an existing. Here is a solution using c#.
using(MyEntities db = new MyEntities()) {
//this will retreieve the customer based on ID
Customer cust = db.Customers.FirstOrDefault(c => c.CustomerID == custID);
//you can update each column
cust.Name = "Test";
//save the changes to the entity
db.SaveChanges();
}
Related
I just changed our database, adding a new column to a table and setting it as a foreign key. We're using EF4 Database first, so I updated the model from the DB, added my new field to the DTOs and everything looked great until I tried to save data to it.
The new column is called DiaryEventId, and because it's a FK there's also a virtual property on the object called DiaryEvent. Here's what the code looks like:
public void SaveDocument(Guid CaseId, string diaryText, string ActivityType)
{
Guid eventTypeId = RepositoryHelper.GetDiaryEventFromCache("Document Uploaded", _commonQueryContext);
//this wanders off and created a diary event object, adds it to
//the context and returns its ID
Guid diaryId = RepositoryHelper.AuditEvent(CaseId, diaryText, commonUpdateContext);
Entities.DocumentMetadata docData = new Entities.DocumentMetadata()
{
Id = Guid.NewGuid();,
ActivityType = activityType,
DiaryEventId = diaryId
};
_commonUpdateContext.DocumentMetadatas.Add(docData);
_commonUpdateContext.SaveChanges();
}
This compiles and runs fine, and when you step through it it appears to function as expected - diaryId is generated and set on the object. But in the DB, it always appears as null.
I've tried calling SaveChanges after adding the diary event (to make sure the key has something to connect to) and I've tried adding the actual DiaryEvent object to the virtual property rather than just the ID - both have the same effect.
When I watch what's going on in SQL Profiler, I can see that the INSERT statement simply ignores my new column completely - it's not listed in the insert columns at all.
Really got no idea what's going on. Any ideas?
Try modifying the object after adding it to the context, just as a test.
_commonUpdateContext.DocumentMetadatas.Add(docData);
Entities.DocumentMetadata docData = new Entities.DocumentMetadata()
{
Id = Guid.NewGuid();,
ActivityType = activityType,
DiaryEventId = diaryId
};
_commonUpdateContext.SaveChanges();
Or is this perhaps a typo?
Entities.DocumentMetadata docData = new Entities.DocumentMetadata()
{
Id = Guid.NewGuid();, <-------------typo?
Beyond that, it will require a bit of info on how you have your entities mapped out. Is there a navigation property between DiaryEvent and DocumentMetadata? Is the key defined as nullable (I'm assuming it is)? Is ActivityType getting persisted correctly?
I want to use EF DbContext/POCO entities in a detached manner, i.e. retrieve a hierarchy of entities from my business tier, make some changes, then send the entire hierarchy back to the business tier to persist back to the database. Each BLL call uses a different instance of the DbContext. To test this I wrote some code to simulate such an environment.
First I retrieve a Customer plus related Orders and OrderLines:-
Customer customer;
using (var context = new TestContext())
{
customer = context.Customers.Include("Orders.OrderLines").SingleOrDefault(o => o.Id == 1);
}
Next I add a new Order with two OrderLines:-
var newOrder = new Order { OrderDate = DateTime.Now, OrderDescription = "Test" };
newOrder.OrderLines.Add(new OrderLine { ProductName = "foo", Order = newOrder, OrderId = newOrder.Id });
newOrder.OrderLines.Add(new OrderLine { ProductName = "bar", Order = newOrder, OrderId = newOrder.Id });
customer.Orders.Add(newOrder);
newOrder.Customer = customer;
newOrder.CustomerId = customer.Id;
Finally I persist the changes (using a new context):-
using (var context = new TestContext())
{
context.Customers.Attach(customer);
context.SaveChanges();
}
I realise this last part is incomplete, as no doubt I'll need to change the state of the new entities before calling SaveChanges(). Do I Add or Attach the customer? Which entities states will I have to change?
Before I can get to this stage, running the above code throws an Exception:
An object with the same key already exists in the ObjectStateManager.
It seems to stem from not explicitly setting the ID of the two OrderLine entities, so both default to 0. I thought it was fine to do this as EF would handle things automatically. Am I doing something wrong?
Also, working in this "detached" manner, there seems to be an lot of work required to set up the relationships - I have to add the new order entity to the customer.Orders collection, set the new order's Customer property, and its CustomerId property. Is this the correct approach or is there a simpler way?
Would I be better off looking at self-tracking entities? I'd read somewhere that they are being deprecated, or at least being discouraged in favour of POCOs.
You basically have 2 options:
A) Optimistic.
You can proceed pretty close to the way you're proceeding now, and just attach everything as Modified and hope. The code you're looking for instead of .Attach() is:
context.Entry(customer).State = EntityState.Modified;
Definitely not intuitive. This weird looking call attaches the detached (or newly constructed by you) object, as Modified. Source: http://blogs.msdn.com/b/adonet/archive/2011/01/29/using-dbcontext-in-ef-feature-ctp5-part-4-add-attach-and-entity-states.aspx
If you're unsure whether an object has been added or modified you can use the last segment's example:
context.Entry(customer).State = customer.Id == 0 ?
EntityState.Added :
EntityState.Modified;
You need to take these actions on all of the objects being added/modified, so if this object is complex and has other objects that need to be updated in the DB via FK relationships, you need to set their EntityState as well.
Depending on your scenario you can make these kinds of don't-care writes cheaper by using a different Context variation:
public class MyDb : DbContext
{
. . .
public static MyDb CheapWrites()
{
var db = new MyDb();
db.Configuration.AutoDetectChangesEnabled = false;
db.Configuration.ValidateOnSaveEnabled = false;
return db;
}
}
using(var db = MyDb.CheapWrites())
{
db.Entry(customer).State = customer.Id == 0 ?
EntityState.Added :
EntityState.Modified;
db.SaveChanges();
}
You're basically just disabling some extra calls EF makes on your behalf that you're ignoring the results of anyway.
B) Pessimistic. You can actually query the DB to verify the data hasn't changed/been added since you last picked it up, then update it if it's safe.
var existing = db.Customers.Find(customer.Id);
// Some logic here to decide whether updating is a good idea, like
// verifying selected values haven't changed, then
db.Entry(existing).CurrentValues.SetValues(customer);
I have this entity, want to update using entityframework
EmployeeModel employee = new EmployeeModel
{
Id = 1000, //This one must
FirstName = modifiedValue,
Email = modifiedValue,
LastName = originalValue,
Phone = originalValue
};
Code to update
_db.ObjectStateManager.ChangeObjectState(employee, EntityState.Modified);
_db.SaveChanges();
This is the SQL statement got once updated
Update Employee set Id=1138,FirstName='modifiedValue',Email='modifiedValue',LastName= 'OriginalValue',phone='originalValue' where Id=1138
But I am expecting this
Update Employee set FirstName='modifiedValue', Email='modifiedValue' where Id=1138.
I dont know what I am missing here. Please let me know.
This problem is common when dealing with DTOs. An employee entity is fetched from the database, mapped to a DTO and sent over the wire. The client then modifies this DTO and sends it back to the server.
When you touch (set) a property on an EF entity, EF will assume that the value has been changed. Even if the old value and the new value are exactly the same.
The same problem occurs when you map the DTO to a new Entity and attach it to EF and updating its status to 'Modified'.
Using AutoMapper:
// This will result in the full update statement
var employee = AutoMapper.Mapper.Map<EmployeeDto, Employee>(dto);
// This will result in a smaller update statement (only actual changes)
var employee = dbContext.Employees.Find(dto.Id);
AutoMapper.Mapper.Map(dto, employee);
Or, manually (I would avoid doing this, but just for the sake of completeness):
// This will result in a smaller update statement (only actual changes)
var employee = dbContext.Employees.Find(dto.Id);
if (employee.Email != dto.Email )
employee.Email = dto.Email;
There are probably some other ways for dealing with this problem... but using AutoMapper together with Entity Framework correctly is definitely one of the easiest ways.
This is the solution I got
var entity = _db.CreateObjectSet<Employee>();
entity.Detach(employee);
entity.Attach(employee);
foreach (string modifiedPro in employeeModel.ModifiedProperties){
_db.ObjectStateManager.GetObjectStateEntry(employee).SetModifiedProperty(modifiedPro);}
_db.SaveChanges();
Only modified values in the sql update statement
Update Employee set FirstName='modifiedValue', Email='modifiedValue' where Id=1138.
If anybody knows better answer than this, Please post your suggestions
You can try this way
public update(Person model)
{
// Here model is model return from form on post
var oldobj = db.Person.where(x=>x.ID = model.ID).SingleOrDefault();
var UpdatedObj = (Person) Entity.CheckUpdateObject(oldobj, model);
db.Entry(oldobj).CurrentValues.SetValues(UpdatedObj);
}
public static object CheckUpdateObject(object originalObj, object updateObj)
{
foreach (var property in updateObj.GetType().GetProperties())
{
if (property.GetValue(updateObj, null) == null)
{
property.SetValue(updateObj,originalObj.GetType().GetProperty(property.Name)
.GetValue(originalObj, null));
}
}
return updateObj;
}
Example:
I am entering a new invoice. For this invoice I need to enter a customer. Lets assume that we retrieved a list of customers:
var list = Context.Set<Customer>().ToList();
Here I see two issues:
1) I do not need to bring all information for customer, I only need Id, Code and Name
2) Customer in current DbContext is read-only, so it would be nice if it is possible to tell DbContext not to monitor their states, to improve performance.
Questions:
1) Can we load only partial data for customer, but still be able to assign it to Invoice (see code bellow)?
2) Can we tell DbContext not to monitor Customers for changes, and still be able to do this:
Invoice.Customer = CustomerList[10];
There's not a direct way to do exactly what you want, but you might be able to achieve your goals with some compromise.
I do not need to bring all information for customer, I only need Id,
Code and Name
There isn't a way for EF to create a partially loaded entity, but you could create an anonymous type:
Context.Customers.Select(c => new {Id = c.CustomerId, Code = c.Code, Name = c.Name}).Tolist()
If you could live with the new anonymous type then use that, or you could then iterate through that list, creating actual customer objects.
Customer in current DbContext is read-only, so it would be nice if it
is possible to tell DbContext not to monitor their states, to improve
performance.
EF provides an Extension of AsNoTracking() which will do exactly what you're looking for:
var list = Context.Set<Customer>().AsNoTracking().ToList();
Depending on what you choose from above, the following code may change, but this code does achieve what you're looking for. Partially loads the customer, but still allows you to attach the customer to the invoice.
Note: You'll need to attach the customer to your context before you can use it, and then setting it to a state of Unchanged will prevent it from overwriting exiting data.
m = new Model();
var list = m.Customers.Select(c => new {Id = c.CustomerId, Code = c.Code, Name = c.Name});
List<Customer> customerList = new List<Customer>();
foreach (var item in list)
{
customerList.Add(new Customer()
{
CustomerId = item.Id,
Code = item.Code,
Name = item.Name
});
}
Invoice i = new Invoice();
var customer = customerList.First();
m.Customers.Attach(customer);
m.Entry(customer).State = EntityState.Unchanged;
i.Customer = customer;
m.Invoices.Add(i);
m.SaveChanges();
I'm having the same problem that a few of you have had - when trying to insert a new object, EF inserts null values for some of their properties, and the insert fails.
First let me describe the structure of our DB. Its an event management system, in which each event needs to be associated with a practice group, stored in a cache table but ultimately fetched from Active Directory. I manually created the join table - is that a problem? Anyway, so Event has a foreign key pointing to EventPracticeGroup, which has a foreign key pointing to PracticeGroupCache. PracticeGroupCache also has a RegionId pointing to the Regions table.
The problem comes when trying to insert a new EventPracticeGroup object. Below is the code I'm currently using:
var eventPracticeGroup = new EventPracticeGroup();
if (TryUpdateModel<EventPracticeGroup>(eventPracticeGroup))
{
/*
var eventId = EventScheduleRepository.GetById(Convert.ToInt32(Request.QueryString["EventScheduleId"])).EventId;
eventPracticeGroup.Event = EventRepository.GetById(eventId);
eventPracticeGroup.PracticeGroupCache = PracticeGroupCacheRepository.GetById(eventPracticeGroup.PracticeGroupCacheId);
eventPracticeGroup.PracticeGroupCache.Region = RegionRepository.GetById(eventPracticeGroup.PracticeGroupCache.RegionId);
EventPracticeGroupRepository.Add(eventPracticeGroup);
*/
var eventId = EventScheduleRepository.GetById(Convert.ToInt32(Request.QueryString["EventScheduleId"])).EventId;
var theEvent = new Event() { Id = eventId };
EventRepository.Repository.UnitOfWork.Context.AttachTo("Events",theEvent);
var practiceGroupCache = new PracticeGroupCache() { Id = eventPracticeGroup.PracticeGroupCacheId };
practiceGroupCache.Region = new Region() { Id = eventPracticeGroup.PracticeGroupCache.RegionId };
eventPracticeGroup.PracticeGroupCache = practiceGroupCache;
EventPracticeGroupRepository.Add(eventPracticeGroup);
EventPracticeGroupRepository.Save();
return RedirectToAction("Index");
}
Anyway... as you can see, I've just tried using stub objects (no help), and I've also tried actually fetching and setting the objects. The error I get is:
Cannot insert the value NULL into column 'Name', table 'XXXX.dbo.Regions'; column does not allow nulls. INSERT fails. The statement has been terminated.
Obviously name is not a key field. I have checked the EDMX XML - only the Id (primary key columns) have StoreGeneratedPattern set to Identity, as they should (they are int32 identity columns). Not a single foreign key has StoreGeneratedPattern set to identity.
if I set Regions.Name to allow nulls, PracticeGroupCaches.Description throws the same error. It seems that every linked object gets set to null. I did have a look with the debugger, when I used the now commented out code, nothing was null and everything had a value. I even got the RegionRepository to return all of the regions, just to see if one of them somewhere had a null name. None did. There are only 2 in my test DB. Our object context is shared per HTTP request.
Please can anyone help. At this point I would settle for using the dirtiest workaround as long as it worked.
Regards,
Jonathan.
Look what happens when you call this line:
EventPracticeGroupRepository.Add(eventPracticeGroup);
You are adding a new eventPracticeGroup to the context. But eventPracticeGroup has the other related objects:
eventPracticeGroup -> PracticeGroupCache -> Region
And you create new objects for those:
var practiceGroupCache = new PracticeGroupCache() {
Id = eventPracticeGroup.PracticeGroupCacheId };
practiceGroupCache.Region = new Region() {
Id = eventPracticeGroup.PracticeGroupCache.RegionId };
eventPracticeGroup.PracticeGroupCache = practiceGroupCache;
When you add the eventPracticeGroup to the context this whole object graph gets added which means that EF considers all three objects as new which have to be added to the DB. Since you only fill the Id properties other string properties (like Name or Description) are null. Because they are not nullable in the database the INSERT command fails.
But I guess that you don't want to insert the related entities into the DB anyway but only the eventPracticeGroup. So you need to attach them to the context before you add the new object, something like:
var practiceGroupCache = new PracticeGroupCache() {
Id = eventPracticeGroup.PracticeGroupCacheId };
EventRepository.Repository.UnitOfWork.Context.AttachTo(
"PracticeGroupCaches",practiceGroupCache);
practiceGroupCache.Region = new Region() {
Id = eventPracticeGroup.PracticeGroupCache.RegionId };
EventRepository.Repository.UnitOfWork.Context.AttachTo(
"Regions",practiceGroupCache.Region);
eventPracticeGroup.PracticeGroupCache = practiceGroupCache;
EventPracticeGroupRepository.Add(eventPracticeGroup);
BTW as a side note: About this EventRepository.Repository.UnitOfWork.Context.XXX take a look at Ladislav Mrnka's answer here: EF 4.0 IsAttachedTo extension method and error An object with the same key already exists
Try to Add: [DatabaseGenerated(DatabaseGeneratedOption.None)]
On your Id field, Like:
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int Id { get; set; }
It seems like you already found the problem and the solution. In your DB schema it seems like the columns don't allow NULL values. So either change all these columns to allow NULL or don't insert null (this is what you currently are trying to do)