I've inherited a project that uses EF 6.2 and the AddOrUpdate method during the Migrations Seed() process.
With a clean database, this code works just fine. Once there is data though, the update piece is giving me problems.
We add the new template as seen below. Then we add the template to the Event.Templates collection. On the ADD version of this, starting from a clean database or no database, this fills in the Template.Event_Id Foreign Key value as expected.
But during the Update, once Events and Templates exist, it adds the new Template but leaves the Event_ID as null. There are other examples that I've checked against and those seem to have worked, or someone may have manually edited the database after the fact.
Any idea why it's doing this?
Template NbCaseConfirmationCarrierSubmissionAppTemplate = new Template
{
NotificationType = "app",
TemplateName = "NB Case Confirmation of Carrier Submission App Template",
TemplateSubject = #"#Model.EventData.CompanyName's enrollment has been submitted to #Model.EventData.CaseCarrier",
TemplateBody = #"",
JsonPayload = #"",
TemplateHistory = new List<TemplateHistory>()
};
context.Templates.AddOrUpdate(x => x.TemplateName, NbCaseConfirmationCarrierSubmissionAppTemplate);
Event NbCaseConfirmationCarrierSubmissionEvent = new Event
{
EventType = "NbCaseConfirmationCarrierSubmission",
Description = "NB Case Confirmation Carrier Submission",
ProgramId = "BM_CASE_CONFIRMATION_CARRIER_SUBMISSION_NOTICE",
NotifySalesforce = true,
Templates = new List<Template>
{
NbCaseConfirmationCarrierSubmissionEmailTemplate,
NbCaseConfirmationCarrierSubmissionAppTemplate
}
};
context.Events.AddOrUpdate(x => x.EventType, NbCaseConfirmationCarrierSubmissionEvent);
I finally found the issue. The core issue was that they built out the entity classes enough to get the database to build correctly, but they didn't include the FK object or ID on the Template class.
I had to add the below to the Template class:
public virtual Event Event { get; set; }
[Column("Event_Id")]
public int? EventId { get; set; }
Then I had to add the below to the DB Context OnModelCreating method:
modelBuilder.Entity<Template>()
.HasRequired(x => x.Event)
.WithMany(x => x.Templates)
.HasForeignKey(x => x.EventId);
Then I had to rearrange the code I posted in the question to AddOrUpdate the Event before the Template, remove the entries in the Event.Templates, and assign the value to Template.EventId.
Related
Using ASP.NET Core 2.2 with EF Core, I have followed various guides in trying to implement the automatic creation of date/time values when creating either a new record or editing/updating an existing one.
The current result is when i initially create a new record, the CreatedDate & UpdatedDate column will be populated with the current date/time.
However first time I edit this same record, the UpdatedDate column is then given a new date/time value (as expected) BUT for some reason, EF Core is wiping out the value of the original CreatedDate which results in SQL assigning a default value.
Required result I need as follows:
Step 1: New row created, both CreatedDate & UpdatedDate column is given a date/time value (this already works)
Step 2: When editing and saving an existing row, I want EF Core to update the UpdatedDate column with the updated date/time only, BUT leave the other CreatedDate column unmodified with the original creation date.
I'm using EF Core code first, and do no want to go down the fluent API route.
One of the guides i was partially following is https://www.entityframeworktutorial.net/faq/set-created-and-modified-date-in-efcore.aspx but neither this or other solutions I've tried is giving the result I am after.
Baseclass:
public class BaseEntity
{
public DateTime? CreatedDate { get; set; }
public DateTime? UpdatedDate { get; set; }
}
DbContext Class:
public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
{
var entries = ChangeTracker.Entries().Where(E => E.State == EntityState.Added || E.State == EntityState.Modified).ToList();
foreach (var entityEntry in entries)
{
if (entityEntry.State == EntityState.Modified)
{
entityEntry.Property("UpdatedDate").CurrentValue = DateTime.Now;
}
else if (entityEntry.State == EntityState.Added)
{
entityEntry.Property("CreatedDate").CurrentValue = DateTime.Now;
entityEntry.Property("UpdatedDate").CurrentValue = DateTime.Now;
}
}
return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
}
UPDATE FOLLOWING ADVICE FROM STEVE IN COMMENTS BELOW
I spent a bit more time debugging today, turns out the methods I posted above are appear to be functioning as expected i.e. when editing an existing row and saving it, only the entityEntry.State == EntityState.Modified IF statement is being called. So what I'm finding is that after saving the entity, the CreatedDate column is being overwitten with a Null value, I can see this by watching the SQL explorer after a refresh. I believe the issue is along the lines of what Steve mentions below "If it is #null then this might also explain the behavior in that it is not being loaded with the entity for whatever reason."
But i'm a little lost in tracing where this CreatedDate value is being dropped somewhere through edit/save process.
Image below shows the result at the point just before the entity is saved following an update. In the debugger I'm not quite sure where to find the entry of the CreatedDate to see what value is held at this step, but it appears to be missing from the debugger list so wandering whether somehow it doesn't know about the existence of this field when saving.
Below is the method I have in my form 'Edit' Razor page model class:
public class EditModel : PageModel
{
private readonly MyProject.Data.ApplicationDbContext _context;
public EditModel(MyProject.Data.ApplicationDbContext context)
{
_context = context;
}
[BindProperty]
public RuleParameters RuleParameters { get; set; }
public async Task<IActionResult> OnGetAsync(int? id)
{
if (id == null)
{
return NotFound();
}
RuleParameters = await _context.RuleParameters
.Include(r => r.SystemMapping).FirstOrDefaultAsync(m => m.ID == id);
if (RuleParameters == null)
{
return NotFound();
}
ViewData["SystemMappingID"] = new SelectList(_context.SystemMapping, "ID", "MappingName");
return Page();
}
public async Task<IActionResult> OnPostAsync()
{
if (!ModelState.IsValid)
{
return Page();
}
_context.Attach(RuleParameters).State = EntityState.Modified;
try
{
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!RuleParametersExists(RuleParameters.ID))
{
return NotFound();
}
else
{
throw;
}
}
return RedirectToPage("./Index");
}
private bool RuleParametersExists(int id)
{
return _context.RuleParameters.Any(e => e.ID == id);
}
}
Possibly one of the reasons for this issue is the fact that I have not included the CreatedDate field in my Edit Razor Page form, so when I update the entity which in turn will run the PostAsync method server side, there is no value stored for the CreatedDate field and therefore nothing in the bag by the tine the savechangesasync method is called in my DbContext Class. But I also didn't think this was necessary? otherwise I'd struggle to see what value there is in the this process of using an inherited BaseEntity class i.e. not having to manually add the CreatedDate & UpdatedDate attribute to every model class where I want to use it...
It may be easier to just give your BaseEntity a constructor:
public BaseEntity()
{
UpdatedDate = DateTime.Now;
CreatedDate = CreatedDate ?? UpdatedDate;
}
Then you can have your DbContext override SaveChangesAsync like:
public override Task<int> SaveChangesAsync(
bool acceptAllChangesOnSuccess,
CancellationToken token = default)
{
foreach (var entity in ChangeTracker
.Entries()
.Where(x => x.Entity is BaseEntity && x.State == EntityState.Modified)
.Select(x => x.Entity)
.Cast<BaseEntity>())
{
entity.UpdatedDate = DateTime.Now;
}
return base.SaveChangesAsync(acceptAllChangesOnSuccess, token);
}
Possibly one of the reasons for this issue is the fact that I have not included the CreatedDate field in my Edit Razor Page form, so when I update the entity which in turn will run the PostAsync method server side, there is no value stored for the CreatedDate field and therefore nothing in the bag by the tine the savechangesasync method is called in my DbContext Class.
That's true.Your post data does not contains the original CreatedDate,so when save to database, it is null and could not know what the exact value unless you assign it before saving.It is necessary.
You could just add below code in your razor form.
<input type="hidden" asp-for="CreatedDate" />
Update:
To overcome it in server-side,you could assign data manually:
public async Task<IActionResult> OnPostAsync()
{
RuleParameters originalData = await _context.RuleParameters.FirstOrDefaultAsync(m => m.ID == RuleParameters.ID);
RuleParameters.CreatedDate = originalData.CreatedDate;
_context.Attach(RuleParameters).State = EntityState.Modified;
await _context.SaveChangesAsync();
}
I don't suspect EF is doing this, but rather your database, or you're inadvertently inserting records instead of updating them.
A simple test: Put break-points in your SaveChangesAsnc method within both the Modified and Added handlers and then run a unit test that loads an entity, edits it, and saves. Which breakpoint is hit? If the behavior seems to be normal with a simple unit test, repeat again with your code.
If the Modified breakpoint is hit, and only the Modified handler is hit then check the state of the CreatedDate value in the entity modified. Does it still reflect the original CreatedDate? If yes, then it would appear that something in your schema will be overwriting it on save. If no then you have a bug in your code that has caused it to update. If it is #null then this might also explain the behaviour in that it is not being loaded with the entity for whatever reason. Check that the property has not been configured as something like a Computed property.
If the Added breakpoint is hit at all, then this would point at a scenario where you're dealing with a detached entity, such as an entity that was read from a different DB Context and being associated to another entity in the current DB Context and saved as a byproduct. When a DbContext encounters an entity that was loaded and disassociated with a different DbContext, it will treat that entity as a completely new entity and insert a new record. The biggest single culprit for this is invariably MVC code where people pass entities to/from views. Entity references are loaded in one request, serialized to the view, and then passed back on another request. Devs assume they are receiving an entity that they can just associate to a new entity and save, but the Context of this request doesn't know about that entity, and that "entity" isn't actually an entity, it is now a POCO shell of data that the serializer created. It's no different to you newing up a new class and populating fields. EF won't know the difference. The result of this is you will trip the Added condition for your entity, and after completion you will have a duplicate record. (with different PK if EF is configured to treat PKs as Identity)
So an example is an Order screen: When presenting a screen to create a new order I may have loaded the Customer and passed that to the view to display customer information and will want to associate to the new order:
var customer = context.Customers.Single(x => x.CustomerId == 15);
var newOrder = new Order { Customer = customer };
return View(newOrder);
This looks innocent enough. When we go to save the new order after setting their details:
public ActionResult Save(Order newOrder)
{
context.Orders.Add(newOrder);
newOrder.Customer.Orders.Add(newOrder);
context.SaveChanges();
// ...
}
newOrder had a reference to Customer #14, so all looks good. We're even associating the new order to the customer's order collection. We might even want to have updated fields on the customer record to reflect a change to the Modified date. However, newOrder in this case, and all associated data including .Customer are plain 'ol C# objects at this point. We've added the new order to the Context, but as far as the context is concerned, the Customer referenced is also a new record. It will ignore the Customer ID if that is set as an Identity column and it will save a brand new Customer record (ID #15 for example) with all of the same details as Customer ID 14 and associate that to the new order. It can be subtle and easy to miss until you start querying Customers and spotting duplicate looking rows.
If you are passing entities to/from views, I'd be very wary of this gotcha. Attaching and setting modified state is one option, but that involves trusting that the data has not been tampered with. As a general rule, calls to update entities should never pass entities & attach them, but rather re-load those entities, validate row version, validate the data coming in, and only copy across fields you expect should ever be modified before saving the entity associated to the DbContext.
Hopefully that gives you a few ideas on things to check to get to the bottom of the issue.
I need to load records from an existing database into a new database using a LINQ query using LINQPad. If the record exists in the database, then update the name. Otherwise, insert the record. Currently, the new DB is empty. This script will run periodically, so I have to check for updates. I have code that loads the existing and new records into two List for comparison. I loop through the list:
foreach (Coaster oldCoaster in listOfOldCoasters) {
var coaster = listOfNewCoasters.Where(c => c.coasterId == oldCoaster.coasterId).FirstOrDefault();
if (coaster != null) {
coaster.Name = oldCoaster.Name;
} else {
coaster = new Models.Coaster();
coaster.CoasterId = oldCoaster.coasterId;
coaster.Name = oldCoaster.Name;
//newCoasterDbContext.Coasters.Attach(coaster);
newCoasterDbContext.Coasters.Add(coaster);
}
}
newCoasterDbContext.SaveChanges();
When I run the code using the "Add" method, I receive the exception "OriginalValues cannot be used for entities in the Added state." Digging deeper, I see this message:
Cannot insert the value NULL into column 'CoasterId', table 'Coaster'; column does not allow nulls.
I am setting the primary key in question, so I must be missing something about EF as to why this fails. If I uncomment the "Attach" statement and try that instead of "Add", then the script runs, but nothing gets inserted into the database.
My Coaster class:
public class Coaster
{
public System.Guid CoasterId { get; set; }
public string Name { get; set; }
public Coaster()
{
CoasterId = System.Guid.NewGuid();
}
}
Based on other posts, I have tried adding attributes to the PK:
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
And I have tried modifying the OnModelCreating method:
HasKey(x => x.CoasterId).Property(x => x.CoasterId).HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.None);
These haven't worked for me. What have I missed that is causing Entity Framework to ignore the GUID that I have attached to the primary key field?
You can't fix stupid, but you can fix stupid mistakes. So as I mentioned, in the OnModelCreating method, I had this line:
HasKey(x => x.CoasterId).Property(x => x.CoasterId).HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.None);
I thought it didn't work, but that was only because a bit later in the method, there was a line that overwrote change:
Property(x => x.FpoDistrictId).HasColumnName(#"FPODistrictId").HasColumnType("uniqueidentifier").IsRequired().HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity);
At least I figured it out...
I have a code first model with a mapping table so that I can map MenuItem to an IdentityRole, enabling the production of a menu based on the logged in users role assignment.
public class MenuItem
{
public int Id { get; set; }
public string Text { get; set; }
}
public class MenuRoleMap
{
[Key]
public int Id { get; set; }
public virtual MenuItem MenuItem { get; set; }
public virtual IdentityRole Role { get; set; }
}
The IdentityRole and rest of Identity is auto wired via IdentityDbContext which I've inherited through my ApplicationDbContext like this, then the context should be consistent.
public class ApplicationDbContext : IdentityDbContext<User>
All of the tables look right, they have the expected columns and foreign keys, here is the MenuRoleMap table
I have an valid existing instance of MenuItem and IdentityRole which I use to try and add a new entity item to this table
foreach (IdentityRole role in selectedRoles)
{
MenuRoleMap mrm = new MenuRoleMap();
mrm.MenuItem = menuItem;
mrm.Role = role;
db.MenuRoleMaps.Add(mrm);
}
db.SaveChanges(); /// <<<=== HERE ERROR BECAUSE THE role IS ALREADY IN DB
Which throws this error
A first chance exception of type 'System.Data.Entity.Validation.DbEntityValidationException' occurred in EntityFramework.dll
Role: Role SystemsAdministrator already exists.
Which of course, it does exist, I know that, it's already in the database. Surely the EF should not be trying to add a new entity item for the foreign key entity if it already exists?
It doesn't do it for the MenuItem, only the IdentityRole.
I thought the problem was proxy creation since the IdentityRole was a proxy object, so I turned that off
this.Configuration.ProxyCreationEnabled = false;
but I still get the same error.
My question is, how do you add an entity where the foreign key is an IdentityRole?
Thank you stackers.
ANSWER TO MY OWN QUESTION
After assistance from those below I discovered while investigating the various solutions that the problem wasn't one of context per se but the validity of an object. The object looked right, what I hadn't realised is that it wasn't the object from the context, it was a facsimile. By trying to add this facsimile to the model, the context quite rightly says it already exists, you can't add it again. By trying to override the state of the item I created a different kind of error.
The resolution was simply to reload the object from the context and then add that to the parent item like so
foreach (IdentityRole role in selectedRoles)
{
// Here I'm getting the role from the context using the ID I have from the facsimile
IdentityRole roleToUse = db.Roles.Where(x => x.Id == role.Id).FirstOrDefault();
// carry on as normal
MenuRoleMap mrm = new MenuRoleMap();
mrm.MenuItem = menuItem;
mrm.Role = roleToUse; // note I'm using the retrieved 'roleToUse'
db.MenuRoleMaps.Add(mrm);
}
db.SaveChanges();
Hey presto it all works.
It looks like you've retrieved the entity from another context and then assigned it to an entity which is then added to a different context. It would then try to insert the Role entity too.
Are you returning the Role from another method where the lifetime of the context is scoped to that method?
You may find the following link useful in regards to updating the state of objects:
Entity states and SaveChanges
The problem is that when you use db.Set<MyEntity>.Add you will mark all entities that are attached to the entity that is added as being added too. You have to explicitly mark them as being unchanged:
foreach (IdentityRole role in selectedRoles)
{
MenuRoleMap mrm = new MenuRoleMap();
mrm.MenuItem = menuItem;
mrm.Role = role;
db.MenuRoleMaps.Add(mrm);
db.Entry(role).State=EntityState.Unchanged;
}
db.SaveChanges();
My answer is you can't or at least should not.
Authentication (Roles), and Business (Menu) are different concerns of the application.
For me you have to bring in the ApplicationDb, the part of IdentityDb that you need and organize the synchronisation.
To illustrate my saying: Imaging you use Google or LiveID as authentification provider: can you imagine navigation properties from you ApplicationDd to Google or Microsoft Dbs ?
Clearly not.
So create a AppRole replicating the Role of the authentication database and use this table from your application database to build your menus.
In pseudo code this looks like:
List<Int32> l = IdentityContext.GetRolesForUser(currentUserId);
foreach (AppRole role in AppContext.Roles.Where(r => l.Contains(r.Id)))
{
MenuRoleMap mrm = new MenuRoleMap();
mrm.MenuItem = menuItem;
mrm.Role = role;
appContext.MenuRoleMaps.Add(mrm);
}
appContext.SaveChanges();
Another solution would be to use the same context for Application and Identity.
Inheritance of context seems fine, but I never tested it.
How can I update a single property of a record without retrieving it first?
I'm asking in the context of EF Code First 4.1
Says I have a class User, mapping to table Users in Database:
class User
{
public int Id {get;set;}
[Required]
public string Name {get;set;}
public DateTime LastActivity {get;set;}
...
}
Now I want to update LastActivity of a user. I have user id. I can easily do so by querying the user record, set new value to LastActivity, then call SaveChanges(). But this would result in a redundant query.
I work around by using Attach method. But because EF throws a validation exception on Name if it's null, I set Name to a random string (will not be updated back to DB). But this doesn't seem a elegant solution:
using (var entities = new MyEntities())
{
User u = new User {Id = id, Name="this wont be updated" };
entities.Users.Attach(u);
u.LastActivity = DateTime.Now;
entities.SaveChanges();
}
I would be very appriciate if someone can provide me a better solution. And forgive me for any mistake as this is the first time I've asked a question on SO.
This is a problem of validation implementation. The validation is able to validate only a whole entity. It doesn't validate only modified properties as expected. Because of that the validation should be turned off in scenarios where you want to use incomplete dummy objects:
using (var entities = new MyEntities())
{
entities.Configuration.ValidateOnSaveEnabled = false;
User u = new User {Id = id, LastActivity = DateTime.Now };
entities.Users.Attach(u);
entities.Entry(user).Property(u => u.LastActivity).IsModified = true;
entities.SaveChanges();
}
This is obviously a problem if you want to use the same context for update of dummy objects and for update of whole entities where the validation should be used. The validation take place in SaveChanges so you can't say which objects should be validated and which don't.
I'm actually dealing with this right now. What I decided to do was override the ValidateEntity method in the DB context.
protected override DbEntityValidationResult ValidateEntity(DbEntityEntry entityEntry, IDictionary<object, object> items)
{
var result = base.ValidateEntity(entityEntry, items);
var errors = new List<DbValidationError>();
foreach (var error in result.ValidationErrors)
{
if (entityEntry.Property(error.PropertyName).IsModified)
{
errors.Add(error);
}
}
return new DbEntityValidationResult(entityEntry, errors);
}
I'm sure there's some holes that can be poked in it, but it seemed better than the alternatives.
You can try a sort of hack:
context.Database.ExecuteSqlCommand("update [dbo].[Users] set [LastActivity] = #p1 where [Id] = #p2",
new System.Data.SqlClient.SqlParameter("p1", DateTime.Now),
new System.Data.SqlClient.SqlParameter("p2", id));
I'm using .NET 3.5 SP1 in ASP.NET MVC application.
While using ObjectContext with Http Request lifetime, and trying to attach an entity ALREADY present in context, we get error:
"An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key."
For Example, the code :
Category newCategory = new Category {CategoryId = CategoryIdSelected};
ctx.AttachTo("CategorySet", newCategory);
will give error if 'Category' with CategoryId = CategoryIdSelected exists in ObjectContext.
Modified code to check for existing entity:
Category newCategory = new Category {CategoryId = CategoryIdSelected};
ObjectStateEntry stateEntry = null;
if( ctx.ObjectStateManager.TryGetObjectStateEntry(newCategory, out stateEntry)){
//EntityObject already attached in context, get it
newCategory = (EntityObject)stateEntry.Entity;
}else{
ctx.AttachTo("CategorySet", newCategory);
}
The modified code is still giving same error:
"[System.InvalidOperationException] = {"An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key."
Please advise ?
Thank You
QUESTION ADDENDUM:
More problems attaching Entities when using ObjectContext having lifetime of Http Request.
For Example, if we have 'AppUser','Category' and Department entities.
public class AppUser : System.Data.Objects.DataClasses.EntityObject{
public int Uid {get; set;}
public string UserName {get; set;}
public string Password {get; set;}
public Department Dept {get; set;}
public Category catg {get; set;}
...........
}
AppUser has relationship with Department and Category Entities.
Now when trying to attach 'user':
user = new AppUser{Uid=1,catg = new Category {categoryId=10}, Dept = new Department{departmentId=101}, ...}
var key = ctx.CreateEntityKey("AppUserSet", user);
if (ctx.ObjectStateManager.TryGetObjectStateEntry(key, out stateEntry)) {
will work ONLY if, in context :
there is NO Category with categoryId=10, and
there is NO Department with departmentId=101
One option, is to ensure context does not have attached entities by always retrieving using NOMERGE NoTracking option. BUT I found following problems with MergeOption.NoTracking:
Second call would still result in db hit
You don't get EntityKeys on EntityRefs. So EntityKey of XXXReference is null,which means NO FK Stub. Please see.
How to get EntityKey of Reference w/o loading both ends (both entities)?
Even though Entity are Detached, they have a reference to the DataContext (via entity._realtionships._context). Please see.
Please advise.
Thank You.
Your code is using two different contexts. You check one, and then attach to the other:
if( csContext. //...){
///
}else{
ctx. // ...
}
The entity appears to be in ctx, but not in csContext. My advice is to use only one context at a time whenever possible; it's much less confusing.
Update
OK, you've changed the code in your question.
My guess is that your stub object doesn't have an EntityKey, so TryGetObjectStateEntry is returning false. Try:
if( ctx.ObjectStateManager.TryGetObjectStateEntry(
new EntityKey("MyEntities.CategorySet", "CategoryId", CategoryIdSelected),
out stateEntry)){
Obviously, replace "MyEntities" with the actual model name.