I'm new to MVC and trying to add/ edit records in master detail form. Both masterid and detailid are generated by oracle on insert of record. Thus when I try to call DBContext.SaveChanges() I get error that foreign key is violated and no primary row with id '0' can be found.
Below is the class description.
public class Master
{
public int MasterID { get; set; }
public string MasterTitle { get; set; }
public virtual IList<Detail> Details { get; set; }
}
public class Detail
{
public int DetailID { get; set; }
public int MasterID { get; set; }
public string DetailName { get; set; }
public virtual Master Master { get; set; }
}
Controller code
[HttpPost]
public ActionResult Create(MASTER masterrecord)
{
if (ModelState.IsValid)
{
db.MASTER.Add(masterrecord);
db.SaveChanges();
}
...
}
The primary key (masterid) will get meaningful values only after record is inserted to database. context.SaveChanges() at this point tries to save Client records too with '0' masterid. I searched every where couldn't find anything which could be of useful.
Though of saving only Master table first so that I can retrieve the masterid and us it with DETAIL model. however couldnt find anywhere how to do it using EF5 MVC ASP.NET
Can any one point me to right direction of provide with some working sample?
thanks
Siddhant
You might want to consider using GUIDs instead of ints for your PK. Then in your constructor for Master you can say MasterID = Guid.NewGuid();. This way you don't have to hit the database to find out what the next ID will be.
There is a pro and con list here http://www.codinghorror.com/blog/2007/03/primary-keys-ids-versus-guids.html
If you have set a breakpoint on the Create method and are getting a proper list in your Master object, it may be an issue with the Oracle provider.
As a workaround, you could try to change the method signature to accept your data like the following:
public ActionResult Create(MASTER masterrecord, List<Detail> details)
Then you could first save the masterrecord and subsequently add your details and save again. It's not optimal, but it may work.
Side note: change your IList to an ICollection.
Related
I'm facing a problem with breeze metadata. I developed a system with breeze controller. I see my model in the metadata including all navigation properties. When I fetch the data from the server I see my objects filled with the expected field, but the deserialized object on client side only includes the simple field without the collection.
I see in the metadata and the returned object from the server like following:
public partial class DesignType
{
public DesignType()
{
this.Product = new HashSet<Product>();
}
public int Id { get; set; }
public string Name { get; set; }
public string Code { get; set; }
public virtual ICollection<Product> Product { get; set; }
public virtual VisionType Vision { get; set; }
}
public partial class VisionType
{
public VisionType()
{
this.DesignType = new HashSet<DesignType>();
}
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<DesignType> DesignType { get; set; }
}
Here is the query code :
var query = breeze.EntityQuery.from("Designs");
breeze.manager.executeQuery(query).then(function (queryResult) {
callback(queryResult.results)
}).fail(function (queryFailed) {
error(queryFailed);
});
The results objects only contain the simple data properties and ignors the properties ICollection Product and Vision .
Any ideas.
Thanks in advance...
Your query only asks for the root type, DesignType, so that is all that should be returned. I'll assume that your server side method is not returning the related Product and Vision entities (which it could do but I'm betting that you're not making that happen).
So Breeze is doing what you asked.
If the client wants the related entities, it can ask for them with an expand clause:
breeze.EntityQuery.from("Designs")
.expand('Products, Vision')
Check out the documentation on queries and expand
Update 11 Dec 2013
If I understand your comment, (a) you now understand why you don't see Product because you are neither requesting products on the client nor pushing them out from the server, (b) your web api is including the related Vision instance and (b) you are seeing Vision data in the JSON response from the query.
The remaining mystery is why someDesignType.Vision is returning null.
Please read "Query response debugging" focusing in particular on the reference navigation property and the foreign key property on Product that points back to the DesignType. If you're still mystified, please show us how the details of the Vision navigation property as explained there.
I have an MVC app using EF code first. I add a user to the system and enter pension details, part of this is a dropdown linked to a model called PensionBenefitLevel. This is the model -
[Key]
public int PensionBenefitLevelID { get; set; }
public string DisplayText { get; set; }
public int EmployeePercentage { get; set; }
public int EmployerPercentage { get; set; }
public virtual ICollection<Pension> Pension { get; set; }
When registered I have the PensionBenefitLevelID that came from the dropdown, but in my controller I was to peform a calculation using the EmployerPercentage value that is related to that ID. Can anyone point me in the correct direction?
Do I need to create a variable in the controller and use a linq query to get that value back? I've not been able to find any examples of something similar so if you could point me to one that would be great too.
If I understand the question correctly, you want to get back the entity corresponding to PensionBenefitLevelID and perform a calculation on the EmployerPercentage field.
Since you haven't mentioned what pattern you are using with EF (repository, unit of work, etc.) I can only give you a general answer:
var entity = [Your DB Context].[Your Entity].GetById(pensionBenefitLevelID);
if(entity != null)
{
[Calculation]
}
I'm trying to update a model, but get the error "The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned another non-null value, or the unrelated object must be deleted."
From what I understand from The relationship could not be changed because one or more of the foreign-key properties is non-nullable the problem might be with how Entity Framework handles my virtual ICollection
However I'm not really sure how to implement the solution when using scaffolded repository pattern. Do I have to edit the Save()-method ParentObjectRepository-class?
Actually I really think that there must be some way to make EF understand this. I can't see how the EF-team was thinking "Probably noone is using a collection of objects with a foreign key constraint, lets not support that".
Update
Added code
[HttpPost]
public ActionResult Edit(int id, FormCollection formCollection)
{
var eventRepository = new MagnetEventRepository();
var original = eventRepository.Find(id);
UpdateModel(original);
eventRepository.Save();
return RedirectToAction("Details", "Home", new { slug = original.Slug });
}
public void Save()
{
context.SaveChanges();
}
More code:
public class MagnetEvent
{
public virtual int Id { get; set; }
[Required]
public virtual string Name { get; set; }
[Required]
[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd HH:mm}")]
[DataType(DataType.DateTime)]
public virtual DateTime? StartDate { get; set; }
public virtual string Description { get; set; }
[StringLength(100)]
public virtual string Slug { get; set; }
public virtual int MaximumCapacity { get; set; }
[DataType(DataType.Currency)]
public virtual int TicketPrice { get; set; }
public virtual int LocationId { get; set; }
public virtual Location Location { get; set; }
public virtual Collection<Ticket> Tickets { get; set; }
public virtual Collection<AttendeeInformationField> CaptureAttendeeInformationFields { get; set; }
public virtual int CustomerId { get; set; }
[Required]
public virtual CUSTOMER Customer { get; set; }
}
The Save()-method is from MagnetEventRepository, which is scaffolded from the above class.
Another update
I successfully removed the error by changing MagnetEventId in AttendeeInformationField to nullable int. When examining the database I can see exactly what's wrong.
Let's say I have a single AttendeeInformationField with the value "E-mail". When I edit my MagnetEvent, the AttendeeInformationField updates the MagnetEventId to null and then adds a new post with the correct MagnetEventId and Value.
I'd very much prefer if the posts in AttendeeInformationField were updated instead.
can you add the code for your event object. The one you call original.
It might be so that the UpdateModel change some info on the associated objects and that's not good if so. Not sure about this though I can't see all the code.
I prefer to not uder UptadeModel and instead use a inputmodel or your MVC model as the inparameter and manually map the chages to the loaded original object.
Antoher problem is that I can't see if
eventRepository.Save();
really do an SaveShages? does it? I can se some context code in another method Save?
As the exception say it seams like your associated collections or other associated objects cant find a valid ID value.
Are you Eager-loading the associated objects? like Customer?
One thing of note is that you shouldn't have the [Required] on Customer as its inferred from the fact that your FK isn't nullable. Required should only be used on a navigation property if you do not have the FK in the model.
To try to diagnose the issue, can you load the object and look at it in a debugger, you should expect that both locationId and CustomerId have non-zero values.
I found a solution to my problem. It seems to be a bug (?) in ASP.NET MVC when it comes to UpdateModel and a model containing an ICollection.
The solution is to override the default behaviour, as described in this blog post: http://www.codetuning.net/blog/post/Binding-Model-Graphs-with-ASPNETMVC.aspx
Update
I found a solution! The above only worked when updating existing items in the collection. To solve this, I have to manually check and add new AttendeeInformationFields. Like this:
[HttpPost]
public ActionResult Edit(int id, MagnetEvent magnetEvent)
{
var eventRepository = new MagnetEventRepository();
var original = eventRepository.Find(id);
UpdateModel(original);
foreach (var attendeeInformationField in magnetEvent.CaptureAttendeeInformationFields)
{
var attendeeInformationFieldId = attendeeInformationField.Id;
if (original.CaptureAttendeeInformationFields.AsQueryable().Where(ai => ai.Id == attendeeInformationFieldId).Count() == 0)
{
original.CaptureAttendeeInformationFields.Add(attendeeInformationField);
}
}
eventRepository.Save();
}
Together with the modified DefaultModelBinder, this actually works with both editing and adding. For now I haven't tried deleting.
Still, I hope there is a simpler way to do this. Seems like a lot of coding to do a very basic task.
I have a couple of classes (for this example anyway) that use code first with the entity framework to connect to the database.
public class Customer
{
[Key]
public long CustomerId { get; set; }
public string CompanyName { get; set; }
...
public virtual List<Contact> Contacts { get; set; }
}
public class Contact
{
[Key]
public long ContactId { get; set; }
public string Forename { get; set; }
...
public long CustomerId { get; set; }
public virtual Customer Customer { get; set; }
}
When I hook these up in my context class directly to the db the foreign key relationships hook up fine and I can access the collection of contacts from within the customer class.
class RemoteServerContext : DbContext
{
public DbSet<Customer> Customers { get; set; }
public DbSet<Contact> Contacts { get; set; }
...
}
My problem is that these database tables are used by various different systems and are massive. In order to increase efficiency I have overridden the default behaviour to point at a view (and also a stored proc elsewhere) rather than directly at the table.
public IEnumerable<Customer> Customers ()
{
return Database.SqlQuery<Customer>("SELECT * FROM vw_CustomerList");
}
public IEnumerable<Contact> Contacts()
{
return Database.SqlQuery<Contact>("SELECT * FROM vw_ContactsList");
}
I have made sure that in each of the views I have included the foreign key fields: CustomerId and ContactId.
When I do this however the class joins appear to be lost - there's always a null when I drill into either of the objects where it should be pointing to the other one. I have tried to set up what the foreign key field should point to but this doesn't seem to help either.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Contact>().HasRequired(p => p.Customer)
.WithMany()
.HasForeignKey(k => k.CustomerId);
}
Is there a way to establish the connection when overriding the default behaviour?
There is no overriding in this case. If you removed
public DbSet<Customer> Customers { get; set; }
and replaced it with
public IEnumerable<Customer> Customers ()
{
return Database.SqlQuery<Customer>("SELECT * FROM vw_CustomerList");
}
you have completely changed the behavior. The first uses entities and full power of EF. The second is only helper to execute custom SQL. Second without first or without defining entity in OnModelCreating doesn't use Customer as mapped entity at all - it uses it as any normal class (only mapped entities can use features like lazy loading).
Because your Customer is now mapped to view you cannot use your former Customer class used with table. You must define mapping of Customer to a view by cheating EF:
modelBuilder.Entity<Customer>().ToTable("vw_ContactsList"); // EF code fist has no view mapping
Once you have this you can try again using:
public DbSet<Customer> Customers { get; set; }
Unless your view is updatable you will get exception each time you try to add, update or delete any customer in this set. After mapping relation between Customer and Contact mapped to views your navigation properties should hopefully work.
The problem with SqlQuery is the way how it works. It returns detached entities. Detached entities are not connected to the context and they will not lazy load its navigation properties. You must manually attach each Customer instance back to context and to do that you again need DbSet.
Am having trouble finding a clear answer to my situation when searching Stack Overflow and Google, hopefully someone can point me in the right direction.
My Situation
I want to be able to use a single edit form (in a single View) to update a 3-level-deep hierarchical entity using ASP.NET MVC 3 and Entity Framework 4 CTP (Code-first) - the model consists of Services, which can have many Service Options, which in Turn can have many Inventory Items.
I was expecting to be able to use MVCs default model binder (via TryUpdateModel) to:
Update an existing 'Service' record
Add/Update/Delete 'Service Option' records (attached to the Service) depending on posted values
Add/Update/Delete 'Inventory' records (attached to each Service Option) depending on posted values
My Model
[Bind(Include="Name, ServiceOptions")]
public class Service {
[Key]
public int ServiceID { get; set; }
public string Name { get; set; }
public DateTime DateCreated { get; set; }
public virtual ICollection<ServiceOption> ServiceOptions { get; set; }
}
[Bind(Include="ServiceOptionID, Description, Tags")]
public class ServiceOption {
[Key]
public int ServiceOptionID { get; set; }
public int ServiceID { get; set; } /* parent id reference */
public string Description { get; set; }
public virtual ICollection<Inventory> InventoryItems { get; set; }
}
[Bind(Include = "InventoryID, Description")]
public class Inventory {
[Key]
public int InventoryID { get; set; }
public int ServiceOptionID { get; set; } /* parent id reference */
public string Description { get; set; }
}
Ideal Controller Method:
[HttpPost]
public ActionResult EditService(int id) {
Service service = db.Services.Single(s => s.ServiceID == id);
TryUpdateModel(service); // automatically updates child and grandchild records
if (ModelState.IsValid) {
db.SaveChanges();
return RedirectToAction("Index");
}
return View(service);
}
Is there a way to achieve this utopian dream, or am I barking up the wrong tree? I'm open to using another technology (such as normal EF4, Automapper etc)
Thanks in advance!
With just the default model binder? Probably not.
With a custom one? Probably.
However your issue won't be the model binder itself. Your issue will be that EF and ORMs and ( I think ) in general do not consider removing an item from a collection as a delete operation. In effect what you are telling the ORM is the relationship does not exist, not that a child row needs to be deleted. Depending on your mappings you'll usually get an error like "A referential integrity constraint violation occurred". This won't be because of code first this is just how EF works.
EF works this way by design and is really important for more complex relationships such as when you have m2m relationships which reference other m2m relationships. You really want EF to be able to disambiguate calls for removal of a relationship and calls to remove a row entirely.
Also, IMHO, this technique is also bad because your letting the piece of code responsible for mapping http values also dictate how objects should be persisted. This is a bad move. I consider delete operations a pretty sacrosanct act and shouldn't be left to the ModelBinder alone. Without soft deletes or logging deleting objects should be considered "serious business".