I think I have read every article and stack overflow question regarding this, but cannot work out the solution. Let me start out with my models
public class Entry
{
public Entry ()
{
DateEntered = DateTime.Now;
}
public int Id { get; set; }
[Required]
public string FirstName { get; set; }
[Required]
public string LastName { get; set; }
[Required]
public string Email { get; set; }
public string Number { get; set; }
public string FbId { get; set; }
[ReadOnly(true)]
public DateTime DateEntered { get; set; }
public string AccessToken { get; set; }
//Relationsips
public Backgrounds Background { get; set; }
public Cars Car { get; set; }
}
public class Backgrounds
{
public int Id { get; set; }
public string Name { get; set; }
public string Filename { get; set; }
}
public class Cars
{
public int Id { get; set; }
public string Name { get; set; }
public string FileName { get; set; }
}
Now in my controller, I am updating the entry. Like follows
// PUT /api/entries/5
public HttpResponseMessage Put(Entry entry)
{
if(ModelState.IsValid)
{
_db.Entries.Attach(entry);
_db.Entry(entry).State = EntityState.Modified;
_db.SaveChanges();
return new HttpResponseMessage(HttpStatusCode.NoContent);
}
throw new HttpResponseException(HttpStatusCode.BadRequest);
}
My Entry model gets updated correctly, but if for eg entry.Background.Name changes, this will not be persisted to the database. My controller is accepting the entire entry model including its relationships => Backgrounds and Cars. However any value that is changed to the relationship is not updated or reflected. Any elegant solution without having to query the database then updating? I dont want to have any extra queries or lookups before I update.
Thanks
Tyrone
You must manually tell EF about all changes done to the object graph. You told EF just about change to entry instance but you didn't tell it about any change to related entities or relations itself. There is no elegant way to solve this. You have generally two options:
You will use some DTOs instead your entities and these DTOs will have some flag like IsDirty - when you receive object graph back to your controller you will reconstruct entities from DTOs and set their state based on IsDirty. This solution needs further extensions for example if your client can also delete relations.
You will query object graph from database and merge your incoming changes to entities retrieved from database.
There are some partial solutions like forcing to save changes to all related objects by setting their state to modified and identifying new objects by Id == 0 but again these solutions work only in specific scenarios.
More complex discussion about this problem.
Related
I want to update a List of Custom Objects stored in a class in entity Framework, But I'm running into this error: the entity type list`1 is not part of the model for the current context. I have observed what the problem is, but I don't have enough experience to solve this problem. Refer below code to get a better understanding of the issue at hand.
public class Appointment
{
public int AppointmentID { get; set; }
public int PetID { get; set; }
public int DoctorID { get; set; }
public DateTime AppointmentDate { get; set; }
public Status AppointmentStatus { get; set; }
public virtual List<ObservedPetIssue> ObservedPetIssueID { get; set; }
public string Reason { get; set; }
public virtual List<PrescribedMedicine> Prescription { get; set; }
public virtual List<DiagnosedSymptom> DiagnosedSymptomID { get; set; }
public virtual Vital VitalID { get; set; }
public virtual List<PrescribedTest> PrescribedTestID { get; set; }
public virtual List<Recommendation> RecommendationID { get; set; }
}
This is the class which has a list of other classes and one property which has a single class(Vital).
Here is the observation:
1)If I edit any field like PetID, DoctorID, or AppointmentStatus and write db.Entry(appt).CurrentValues.SetValues(editedAppointment); The changes are saved
If I edit any field inside VitalID and write db.Entry(appt.VitalID).CurrentValues.SetValues(editedAppointment.VitalID); The changes are saved
If I add any PrescribedMedicine to the Prescription list, or modify the existing PrescribedMedicine or not modify anything at all and write db.Entry(appt.PrescribedTestID).CurrentValues.SetValues(editedAppointment.PrescribedTestID); and error is throw stating: the entity type list`1 is not part of the model for the current context
I've Tried db.Entry(appt.Prescription).State = EntityState.Modified, still no success.
That you do is similar that db.Entry(new List<PrescribedTest>()). This fail because the db context don't know the entity type List<PrescribedTest>.
This work with VitalID because it's similar that db.Entry(new Vital()) and that success because the db context know the entity type Vital.
If you want update a full entity collection, you can :
context.Entry(appointment).Collection(a => a.PrescribedTestID).CurrentValue = editedAppointment.PrescribedTestID;
I'm new to c# and I have a basic problem with saving/updating data.
With two classes :
public class User
{
public int UserId { get; set; }
public string Email { get; set; }
public string Login { get; set; }
public string Password { get; set; }
public DateTime RegisteredDate { get; set; }
public class Task
{
public int TaskId { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public string Comment { get; set; }
public User DeclaredBy { get; set; }
}
I'm trying to save a task object (new or updated) with DeclaredBy field set
dbContext.Tasks.AddOrUpdate(task);
dbContext.SaveChanges();
User set in DeclaredBy field has an ID, but after executing SaveChanges() a new record of User appears in DB.
This is how EF works, if you add entity with other related entity then both will be stored in DB. If you want to store only one then you need to set other navigation properties to null and only set foreign key id, which currently you don't have, you should add property:
public int DeclatedById { get; set; }
Btw. this is very common problem and a lot of projects has duplicate values in db.
Maybe I should add that this will happen only if entity wasn't traced by EF context and was attached to it.
I am learning how to use MVC right now and I just have a question on when I am creating and updating entries in the database. I was reading a post from this page: asp.mvc 4 EF ActionResult Edit with not all fields in view
The guy in it said to create a model that will be used, so is the efficient way to insert a new row and update an existing row by having two models with different properties?
So my models would look like this -
public class UserModelView
{
public string FirstName { get; set; }
public string Surname { get; set; }
public DateTime AccountCreated { get; set; }
public DateTime? LastLoggedIn { get; set; }
}
public class UserModelCreate
{
[Key]
public int UserId { get; set; }
public string FirstName { get; set; }
public string Surname { get; set; }
public DateTime AccountCreated { get; set; }
}
public class UserModelUpdate
{
public string FirstName { get; set; }
public string Surname { get; set; }
public DateTime? LastLoggedIn { get; set; }
}
Is this the best way to do what I need to do?
Im guessing you were previously using the entity class when binding your model back in.
You shouldn't do that!
The guy in the post is right, this is a much better way of controlling your entity and model information and provides a layer of seperation between the two.
After all you wouldnt want a user being able to directly manipulate an entity via a HTTP request.
I answered something similar here
I am apparently having a real devil of a time understanding Entity Framework 6 which I am using with ASP.NET MVC 5.
The core of the matter is that I have a really quite simple data model that is typical of any real world situation where I have various business objects that have other business objects as properties (and of course they child objects may in turn have other child business objects) and also various types of lookup/type data (Country, State/Province, LanguageType, StatusType etc.) and I cannot figure out how to save/update it properly.
I keep going back and forth between two error states:
1) I either run into the situation where saving a parent business object results in unwanted duplicate values being inserted into my lookup/type tables (for example saving a business object that has been assigned an existing LanguageType of 'English' will result in another LanguageType for 'English' being inserted into the LanguageType table), or
2) I use some of the suggestions I've seen here and elsewhere on the net (e.g. Saving Entity causes duplicate insert into lookup data, Prevent Entity Framework to Insert Values for Navigational Properties ) to solve issue 1 and then find myself fighting against this same issue: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key .
I will now provide a few code snippets to help build the picture of what I am trying to do and what I am using to do it. First, an example of the entities involved:
public class Customer : BaseEntity
{
public string Name { get; set; }
[LocalizedDisplayName("Contacts")]
public virtual List Contacts { get; set; }
}
public class Contact : BaseEntity
{
[Required]
public string FirstName { get; set; }
[Required]
public string LastName { get; set; }
public int? LanguageTypeID { get; set; }
[Required]
[ForeignKey("LanguageTypeID")]
public virtual LanguageType Language { get; set; }
}
public class LanguageType : Lookup
{
[LocalizedDisplayName("CultureName")]
public string CultureName { get; set; }
}
public class Lookup : BaseEntity
{
public string DisplayName { get; set; }
public int DisplayOrder { get; set; }
public string Name { get; set; }
public string Description { get; set; }
}
public class BaseEntity
{
public int ID { get; set; }
public DateTime? CreatedOn { get; set; }
public DateTime? UpdatedOn { get; set; }
public DateTime? DeletedOn { get; set; }
public bool Deleted { get; set; }
public bool Active { get; set; }
public ApplicationUser CreatedByUser { get; set; }
public ApplicationUser UpdatedByUser { get; set; }
}
In my controller, I have some code like the following:
foreach(Contact contact in lstContacts)
{
customer.Contacts.Add(contact);
}
if (ModelState.IsValid)
{
repository.Add(customer);
}
Let us suppose that each of the contacts has the same LanguageType of 'English' assigned (and in this example it is the fact that I am trying to save multiple contacts that have the same LanguageType that triggers the ObjectStateManager error). Initially, the repository.Add() code just did a context.SaveChanges() which did not work as expected, so now it looks something like this (Entity variable is a Customer):
try
{
if(Entity.Contacts != null)
{
foreach(Contact contact in Entity.Contacts)
{
var entry = this.context.Entry(contact.Language);
var key = contact.Language.ID;
if (entry.State == EntityState.Detached)
{
var currentEntry = this.context.LanguageTypes.Local.SingleOrDefault(l => l.ID == key);
if (currentEntry != null)
{
var attachedEntry = this.context.Entry(currentEntry);
//attachedEntry.CurrentValues.SetValues(entityToUpdate);
attachedEntry.State = EntityState.Unchanged;
}
else
{
this.context.LanguageTypes.Attach(contact.Language);
entry.State = EntityState.Unchanged;
}
}
}
}
context.Customers.Add(Entity);
context.SaveChanges();
}
catch(Exception ex)
{
throw;
}
Is it fundamentally wrong to expect this to have worked? How am I supposed to save and example like this? I have similar problems saving similar object graphs. When I look at tutorials and examples for EF, they are all simple and they all just call SaveChanges() after doing something very similar to what I am doing here.
I've just recently been using the ORM capabilities of ColdFusion (which is hibernate under the covers) and there are would simply load the LanguageType entity, assign it to the Contact entity, save the Contact entity, assign it to the Customer and then save the Customer.
In my mind, this is the most basic of situations and I cannot believe that it has caused me so much pain - I hate to say it, but using plain old ADO.NET (or heaven forbid, ColdFusion which I really don't enjoy) would have been MUCH simpler. So I am missing SOMETHING. I apparently have a key flaw in my understanding/approach to EF and If somebody could help me to make this work as expected and help me to figure out just where my misunderstanding lies, I would greatly appreciate it. I have spend too many hours and hours on this and it is a waste of time - I have/will have countless examples just like this one in the code I am building so I need to adjust my thinking with respect to EF right now so I can be productive and do approach things in the expected way.
Your help will mean so much and I thank you for it!
Let's consider the following object graph in which a teacher instance is the root object,
Teacher --[has many]--> courses
Teacher --[Has One]--> Department
In entity framework's DbContext, each instance of an object has a State indicating whether the object is Added, Modified, Removed or Unchanged. What happens apparently is the following :
Creating the root object for the first time
In this case, in addition to the newly created root object Teacher, ALL the child objects in the graph will have the State Added as well even if they're already created. The solution for this problem is to include the foreign key property for each child element and use it instead, i.e. Teacher.DepartmentId = 3 for example.
Updating the root object and one of its child elements' properties
Suppose you fetch a teacher object from the db, and you change the Teacher.Name property as well as the Teacher.Department.Name property; in this case, only the teacher root object will have the State marked as Modified, the department's State on the other hand remains Unchanged and the modification won't be persisted into DB; Silently without any warning.
EDIT 1
I used your classes as follows and I don't have a problem with persisting the objects :
public class Customer : BaseEntity
{
public string Name { get; set; }
public virtual List<Contact> Contacts { get; set; }
}
public class Contact : BaseEntity
{
public string FirstName { get; set; }
public string LastName { get; set; }
public int? LanguageTypeID { get; set; }
public Customer Customer { get; set; }
[ForeignKey("LanguageTypeID")]
public LanguageType Language { get; set; }
}
public class LanguageType : Lookup
{
public string CultureName { get; set; }
}
public class Lookup : BaseEntity
{
public string DisplayName { get; set; }
public int DisplayOrder { get; set; }
public string Name { get; set; }
public string Description { get; set; }
}
public class BaseEntity
{
public int ID { get; set; }
public DateTime? CreatedOn { get; set; }
public DateTime? UpdatedOn { get; set; }
public DateTime? DeletedOn { get; set; }
public bool Deleted { get; set; }
public bool Active { get; set; }
public ApplicationUser CreatedByUser { get; set; }
public ApplicationUser UpdatedByUser { get; set; }
}
public class ApplicationUser
{
public int ID { get; set; }
public string UserName { get; set; }
public string Password { get; set; }
}
And used the following Context :
public class Context : DbContext
{
public Context() : base("name=CS") { }
public DbSet<Customer> Customers { get; set; }
public DbSet<Contact> Contacts { get; set; }
public DbSet<LanguageType> LanguageTypes { get; set; }
public DbSet<ApplicationUser> ApplicationUsers { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
//I'm generating the database using those entities you defined;
//Here we're demanding not add 's' to the end of table names
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
}
}
Then I created a unit tests class with the following :
[TestMethod]
public void TestMethod1()
{
//our context
var ctx = new Infrastructure.EF.Context();
//our language types
var languageType1 = new LanguageType { ID = 1, Name = "French" };
var languageType2 = new LanguageType { ID = 2, Name = "English" };
ctx.LanguageTypes.AddRange(new LanguageType[] { languageType1, languageType2 });
//persist our language types into db before we continue.
ctx.SaveChanges();
//now we're about to start a new unit of work
var customer = new Customer
{
ID = 1,
Name = "C1",
Contacts = new List<Contact>() //To avoid null exception
};
//notice that we're assigning the id of the language type and not
//an object.
var Contacts = new List<Contact>(new Contact[] {
new Contact{ID=1, Customer = customer, LanguageTypeID=1},
new Contact{ID=2, Customer = customer, LanguageTypeID=2}
});
customer.Contacts.AddRange(Contacts);
//adding the customer here will mark the whole object graph as 'Added'
ctx.Customers.Add(customer);
//The customer & contacts are persisted, and in the DB, the language
//types are not redundant.
ctx.SaveChanges();
}
It all worked smoothly without any problems.
As far as i know there is no build in support for reattaching modified graphs (like the SaveOrUpdate method of nHibernate). Perhaps this or this can help you.
I'm an EF noob (any version) and my Google-foo has failed me on finding out how to do this. Which makes me think I must be doing this wrong, but here is the situation:
I'm definitely in an environment that is database first and the schema won't be updated by us coders. I'm also not a fan of 'automatic' code generation, so I've stayed away from the designer or the EF powertools (though I did run through them just to see them work).
To learn I imported the Northwind DB into my LocalDB to have something to play with while creating some simple Web API 2 endpoints. This all went well as I created slimmed down models of the Employees, Shippers, & Region tables in Northwind. Region was particularly interesting as it wasn't plural and EF had issues with that. Anyway, I got by that.
My trouble now is; I want to use a view instead of a table as my source and whatever I'm doing just doesn't seem to work. What I tried was setting it up just like I did the tables. But that produces a ModelValidationException error. I tried looking at the auto-generated code from the designer, but got no insight.
My models:
//-- employee, shipper, & region work as expected
public class employee {
public int EmployeeID { get; set; }
public string LastName { get; set; }
public string FirstName { get; set; }
}
public class shipper {
public int ShipperID { get; set; }
public string CompanyName { get; set; }
public string Phone { get; set; }
}
public class region {
public int RegionID { get; set; }
public string RegionDescription { get; set; }
}
//-- invoice is a view (actual viewname is 'Invoices')
//-- so i followed the same rules as i did for employee & shipper
//-- i have tried uppercase 'I' as well as a plural version of the model
public class invoice {
public string CustomerID { get; set; }
public string CustomerName { get; set; }
public string Salesperson { get; set; }
public int OrderID { get; set; }
public int ProductID { get; set; }
public string ProductName { get; set; }
}
My Context looks like this:
public class NorthwindDBContext : DbContext {
public DbSet<Employee> Employees { get; set; }
public DbSet<shipper> Shippers { get; set; }
public DbSet<region> Regions { get; set; }
public DbSet<Invoice> Invoices { get; set; } //-- offending line of code
protected override void OnModelCreating(DbModelBuilder modelBuilder) {
//--- fix for Region being singular instead of plural
modelBuilder.Entity<region>().ToTable("Region");
}
}
If I comment out the public DbSet<Invoice> Invoices { get; set; } line in the context everything works. Just by having the line present (even if i don't reference the Invoices property) I receive the ModelValidationException error when using the context in anyway.
Can anybody tell me what I'm doing wrong here?
Thanks.
Update: I tried this in one of my controllers, but I am too noob'ish to know if this is the right path either, though it worked as far as getting records.
using (var dbContext = new NorthwindDBContext()) {
return dbContext.Database.SqlQuery<Invoice>("select * from invoices").ToList();
}
Code-first conventions will look for an ID or InvoiceID property to use as a key. Your Invoice model has neither, while the others do. This is the specific reason your code is failing.
The less-specific one is that you can't have entities in EF which lack a unique key. If you can, have the view define a key. Otherwise, you may still be able to work around the issue.