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Unable to delete record from database Entity Framework C#

Since adding logging functionality to my Entity Framework project, I have been unable to delete any records from the table.
Here are the data classes for the objects which are added to the database, the user to the user table and the log to the logs table:
public class User
{
public string UserName { get; set; }
[Key]
public string ApiKey { get; set; } //unique database key and API key for user
public ICollection<Log> Logs { get; set; }
public User() { }
}
public class Log
{
[Key]
public int logID { get; set; }
public string logString { get; set; }
public string logDateTime { get; set; }
public string userAPIKey { get; set; }
public Log() { }
}
Here is how logs are added to the table, as since adding logging I've been having the issue:
public void addLogToUserWithApiKey(string logMessage, string apiKey)
{
Log newLog = new Log();
newLog.logID = makeLogID();
newLog.logString = logMessage;
newLog.logDateTime = DateTime.Now.ToShortDateString() + " " + DateTime.Now.ToString("h:mm:ss tt");
newLog.userAPIKey = apiKey;
using (var context = new UserContext())
{
User logUser = checkIfUserExistsWithApiKeyandReturnUser(apiKey);
if (logUser.Logs == null)
{
logUser.Logs = new Collection<Log>();
}
logUser.Logs.Add(newLog);
context.Logs.Add(newLog);
context.SaveChanges();
}
}
And finally, this is the code to delete a record:
public void deleteUserFromDatabase(string mApiKey)
{
using (var context = new UserContext())
{
try
{
User userToDelete = checkIfUserExistsWithApiKeyandReturnUser(mApiKey);
if (userToDelete != null)
{
context.Users.Attach(userToDelete);
context.Users.Remove(userToDelete);
context.SaveChanges();
}
}
catch (Exception e) { }
}
}
There were no exceptions being called when the delete method was like that however it still wasn't working.
I changed the delete method to this:
User userToDelete = checkIfUserExistsWithApiKeyandReturnUser(mApiKey);
if (userToDelete != null)
{
if (userToDelete.Logs != null)
{
userToDelete.Logs.ToList().ForEach(log => userToDelete.Logs.Remove(log));
}
context.Users.Attach(userToDelete);
context.Users.Remove(userToDelete);
context.SaveChanges();
}
And I got this error message:
The DELETE statement conflicted with the REFERENCE constraint "FK_dbo.Logs_dbo.Users_User_ApiKey". The conflict occurred in database "SecuroteckWebApplication.Models.UserContext", table "dbo.Logs", column 'userAPIKey'. The statement has been terminated.

If you want to delete a User, you would have to delete all Log entries associated with that user first.
var apiKey = String.Empty; // The id of the user you want to delete
using (var context = new UserContext())
{
User userToDelete = checkIfUserExistsWithApiKeyandReturnUser(apiKey);
if (userToDelete != null)
{
var userLogs = context.Logs.Where(l => l.userAPIKey == apiKey);
if (userLogs.Any())
{
context.Logs.RemoveRange(userLogs);
}
context.Users.Attach(userToDelete);
context.Users.Remove(userToDelete);
context.SaveChanges();
}
}

This error is returned from SQL Server. As it says, you cannot delete the User because there are records from the dbo.Logs table which are related to the deleted user and there is a foreign key defined linking the userAPIKey column with this deleted User.
Seeing your entity code, I can't tell why the foreign key was created in the first place, if you are using Entity Framework Code First. If this is your case, probably you are falling in an Entity Framework convention rule.
Anyways, there are some ways to solve this.
If you are using EF Code First. Delete all the logs pointing to the deleted user or update them setting them to NULL, depending on how much you need to preserve the logs for a deleted user.
EDIT: As the OP is using Code First, then the relationship between Log and User is not completely defined. This is the proper entity code if a strong relationship is what is intended by the OP.
public class User
{
public string UserName { get; set; }
[Key]
public string ApiKey { get; set; } //unique database key and API key for user
[InverseProperty("User")]
public virtual ICollection<Log> Logs { get; set; }
public User() { }
}
public class Log
{
[Key]
public int logID { get; set; }
public string logString { get; set; }
public string logDateTime { get; set; }
public string userAPIKey { get; set; }
[ForeignKey("userAPIKey")
public virtual User User {get; set; }
public Log() { }
}
With the strong relationship, logs should be deleted or set to null before being able to the delete the user if cascade conventions are not configured.

Unable to get Namespace from ObjectStateEntry when saving from a ViewController

I'm attempting to create an Audit Log for my MVC, Entity Framework website project. I've been able to subscribe to SaveChanges() in my DBContext (and save to my database through another DBContext but same database).
My two questions in the end are:
What does if (!entry.IsRelationship) do exactly? I have a ViewModel that calculates this as True when Saving and another as False. I would expect this to move into the rest of my method to save in the Audit Log.
How can I get the full Namespace of my Object being modified? I was using this: entry.Entity.ToString() but doesn't seem to work when Saving/Editing from a View Model (details below)
Here is a basic setup that I have thus far (Album object/controller works, but AlbumView doesn't):
Ablum class:
public class Album : BaseObject //BaseObject has a few properties, one is Oid (Guid)
{
public string Name { get; set; }
[Column(TypeName = "varchar(MAX)")]
[DataType(DataType.MultilineText)]
public string Description { get; set; }
[Display(Name="Genres")]
public virtual ICollection<AlbumsGenres> AlbumGenres { get; set; }
[Display(Name="Artists")]
public virtual ICollection<AlbumsArtists> AlbumArtists { get; set; }
}
AblumView class:
public class AlbumView
{
[ScaffoldColumn(false)]
public Guid Oid { get; set; }
[Required]
public string Name { get; set; }
[Column(TypeName = "varchar(MAX)")]
[DataType(DataType.MultilineText)]
public string Description { get; set; }
[Display(Name = "Genres")]
public virtual List<AlbumsGenres> AlbumGenres { get; set; }
[Display(Name = "Artists")]
public virtual List<AlbumsArtists> AlbumArtists { get; set; }
}
AlbumsController (Audit works with something like this):
public ActionResult Edit(Album album)
{
if (ModelState.IsValid)
{
db.Entry(album).State = EntityState.Modified;
db.SaveChanges(); //This is where SaveChanges() takes over (see below)
return RedirectToAction("Index");
}
return View(album);
}
AlbumsViewController:
public ActionResult Edit(Guid id, AlbumView albumViewModel)
{
//Omitting setup...
//Album gets updated
Album album = db.Albums.Find(id);
album.Name = albumViewModel.Name;
album.Description = albumViewModel.Description;
//Other Objects are also updated, just an example:
albumArtists = new AlbumsArtists();
albumArtists.Oid = Guid.NewGuid();
albumArtists.Album = db.Albums.Find(id);
albumArtists.Artist = db.Artists.Find(item.Artist.Oid);
//In the end it calls:
db.SaveChanges();
//Omitting other stuff...
}
On db.SaveChanges() within my DbContext:
public class ApplicationDBContext : DbContext
{
public ApplicationDBContext() : base("name=DefaultConnection") { }
public System.Data.Entity.DbSet<ContentPub.Models.Music.Album> Albums { get; set; }
//Other DBSet objects...
public DbSet Set(string name)
{
return base.Set(Type.GetType(name));
}
public override int SaveChanges()
{
ApplicationLogDBContext logDb = new ApplicationLogDBContext();
ChangeTracker.DetectChanges();
ObjectContext ctx = ((IObjectContextAdapter)this).ObjectContext;
List<ObjectStateEntry> objectStateEntryList =
ctx.ObjectStateManager.GetObjectStateEntries(EntityState.Added
| EntityState.Modified
| EntityState.Deleted)
.ToList();
foreach (ObjectStateEntry entry in objectStateEntryList)
{
Guid oid = Guid.Empty;
try
{
if (!entry.IsRelationship) //I don't understand this (first of my two questions)
{
switch (entry.State)
{
//Removed other cases
case EntityState.Modified:
{
oid = (Guid)entry.EntityKey.EntityKeyValues[0].Value;
//This is the area that I am having issues (second of the two questions)
//Below will work when I call db.SaveChanges() from the AlbumsController,
//'entry.Entity.ToString()' will get 'x.Models.Music.Albums' and begin a query
var query = this.Set(entry.Entity.ToString()).AsNoTracking().Where("Oid == #0", oid);
//The issue with the above is when I have a ViewModel, returns something like
// = System.Data.Entity.DynamicProxies.Album_AF81C390156ACC8283ECEC668AFB22C4AD621EF70F8F64641D56852D19755BF3
//If the proper Namespace is returned, the next line works and Audit continues
var query = this.Set(entry.EntitySet.ElementType.ToString()).AsNoTracking().Where("Oid == #0", oid);
//Does a bunch of AuditLog stuff if the above issue doesn't fail
break;
}
}
}
}
catch (Exception ex)
{
throw new Exception("Log Error (" + entry.Entity.ToString() + ") - " + ex.ToString());
}
}
return base.SaveChanges();
}
}
entry.Entity.ToString() will return something like:
System.Data.Entity.DynamicProxies.Album_AF81C390156ACC8283ECEC668AFB22C4AD621EF70F8F64641D56852D19755BF3
In the AlbumView I am updating Album, and a bunch of other Objects. Not sure why it isn't returning x.Models.Music.Albums, is there a work-around, can someone explain or point me to other resources that I haven't found yet?

While it isn't the most efficient solution, it still is a solution for now.
I was able to do the following inside my db.SaveChanges() method:
//When AlbumView .BaseType was able to return x.Models.Music.Album
string strNamespace = entry.Entity.GetType().BaseType.ToString();
//Needed this if I was updating just an Object (ie: Album),
//would be nice to make something more concret
if (strNamespace == "x.Models.Core.BaseObject")
strNamespace = entry.Entity.ToString();
//Continuing code
var query = this.Set(strNamespace).AsNoTracking().Where("Oid == #0", oid);
Found the answer here from another Question that I had not found before posting this question

Can't insert entity with foreign key in Entity Framework

I'm building Backend for Mobile Application with ASP.NET MVC Framework.
I have two Objects:
public class CarLogItem : EntityData
{
public CarLogItem(): base()
{
Time = DateTime.Now;
}
public DateTime Time { get; set; }
public int RPM { get; set; }
public int Speed { get; set; }
public int RunTime { get; set; }
public int Distance { get; set; }
public int Throttle { get; set; }
[ForeignKey("Trip")]
public String Trip_id { get; set; }
// Navigation property
public TripItem Trip { get; set; }
}
and
public class TripItem : EntityData
{
public TripItem() : base()
{
UserId = User.GetUserSid();
StartTime = DateTime.Now;
logItems = new List<CarLogItem>();
}
public string UserId { get; set; }
public List<CarLogItem> logItems {get;set;}
public DateTime StartTime { get; set; }
}
and I have controller, which add new CarLogItem to database.
public class CarLogItemController : TableController<CarLogItem>
{
// POST tables/CarLogItem
public async Task<IHttpActionResult> PostCarLogItem(CarLogItem item)
{
var lastItem = db.CarLogItems.OrderByDescending(x => x.Time).FirstOrDefault();
//lastItem = (Query().Where(logitem => true).OrderBy(logitem => logitem.Time)).Last();
//checking if lastItem.Trip isn't null because
// I have entities with Trip field is null, but all of them should have it.
if (lastItem != null && lastItem.Trip != null && item.RunTime > lastItem.RunTime)
{
item.Trip = lastItem.Trip;
}
//In order to test adding of new TripItem entity to database
// I compare item.RunTime with 120, so it always true
else if (lastItem == null || item.RunTime < 120) // < lastItem.RunTime)
{
var newTrip = new TripItem();
item.Trip = newTrip;
}
else
{
throw new ArgumentException();
}
CarLogItem current = await InsertAsync(item);
return CreatedAtRoute("Tables", new { id = current.Id }, current);
}
}
When I'm trying to add new CarLogItem with Trip = null it's ok, but when Trip is particular object it fails with following Exception:
The entity submitted was invalid: Validation error on property 'Id': The Id field is required
How properly to add new CarLogItem with nested TripItem?

I think that you need to populate the Id property on your TripItem, e.g.
var newTrip = new TripItem(){ Id = Guid.NewGuid() }

You need a primary key field in every entity class, like Id or CarLogItemId (ClassName + "Id"). Or just have a property with [Key] attribute:
[Key]
public string/int/Guid/any-db-supported-type MyProp { get; set; }
Entity Framework relies on every entity having a key value that it
uses for tracking entities. One of the conventions that code first
depends on is how it implies which property is the key in each of the
code first classes. That convention is to look for a property named
“Id” or one that combines the class name and “Id”, such as “BlogId”.
The property will map to a primary key column in the database.
Please see this for more details.
I also suspect this to be a problem:
public Lazy<CarLogItem> logItems { get; set; }
You don't have to mark navigation property as Lazy<>. It is already lazy (unless you have configuration that disables lazy loading). Please try to remove Lazy<> and see if it works this way.

How to update a collection inside an entity within a post action in ASP.NET MVC5?

I have created an ASP.NET MVC5 sample project. I created my entities and from that, scaffolded the controllers for CRUD operations. I can only edit the POD members with the scaffolded code. I want to be able to add/remove related entities.
With my current code, when I click save there is no error but no related entities are modified (POD data is modified though). For example, if I wanted to remove all players from the account, they aren't removed. What am I doing wrong?
How can I remove/add related entities and push those changes to the database?
Here is the form:
Here is the action to update the entity:
public async Task<ActionResult> Edit([Bind(Include = "Account,Account.AccountModelId,Account.Name,Account.CreatedDate,SelectedPlayers")] AccountViewModel_Form vm){
if (ModelState.IsValid){
if (vm.SelectedPlayers != null){
vm.Account.PlayerModels = db.PlayerModels.Where(p => p.AccountModel.AccountModelId == vm.Account.AccountModelId).ToList();
foreach (var player in vm.Account.PlayerModels){
player.AccountModel = null;
db.Entry(player).State = EntityState.Modified;
}
vm.Account.PlayerModels.Clear();
foreach (var player_id in vm.SelectedPlayers){
var player = db.PlayerModels.Where(p => p.PlayerModelId == player_id).First();
vm.Account.PlayerModels.Add(player);
db.Entry(player).State = EntityState.Modified;
}
}
db.Entry(vm.Account).State = EntityState.Modified;
await db.SaveChangesAsync();
return RedirectToAction("Index");
}
return View(vm);
}
Here are the models:
public class AccountViewModel_Form{
public AccountModel Account { get; set; }
public HashSet<Int32> SelectedPlayers { get; set; }
public virtual List<PlayerModel> PlayersList { get; set; }
}
public class AccountModel{
public AccountModel(){
PlayerModels = new HashSet<PlayerModel>();
}
public Int32 AccountModelId { get; set; }
public string Name { get; set; }
public DateTime CreatedDate { get; set; }
public virtual ICollection<PlayerModel> PlayerModels { get; set; }
}
public class PlayerModel{
public Int32 PlayerModelId { get; set; }
public float Gold { get; set; }
public string Name { get; set; }
public virtual AccountModel AccountModel { get; set; }
}
I'm basically lost. I can't find any examples in how to update related data. Could someone point me in the right direction?
I come from Symfony (PHP Framework) background. I thought it would be easier but I have been having problems.

Basically I was missing the Attach function and that I had to force the load on the collection to make it work.
I found how to attach a non-attached entity here: Model binding in the controller when form is posted - navigation properties are not loaded automatically
When you post the data, the entity is not attached to the context, and when you try to save changes to a complex entity, the context makes a mess.
The code is a little different because I was trying to make it work at home. But it is essentially the same models.
public ActionResult Edit(AccountEditViewModel vm)
{
if (ModelState.IsValid)
{
//I was missing these 2 important lines...
db.Accounts.Attach(vm.Account);
db.Entry(vm.Account).Collection(a => a.Players).Load();
if (vm.SelectedPlayers != null)
{
foreach (var player in vm.Account.Players.ToList())
{
if (vm.SelectedPlayers.Contains(player.Id) == false)
{
player.Account = null;
vm.Account.Players.Remove(player);
db.Entry(player).State = EntityState.Modified;
vm.SelectedPlayers.Remove(player.Id);
}
}
foreach (var player_id in vm.SelectedPlayers)
{
var player = db.Players.Where(p => p.Id == player_id).First();
player.Account = vm.Account;
vm.Account.Players.Add(player);
db.Entry(player).State = EntityState.Modified;
}
}else
{
vm.Account.Players.Clear();
}
db.Entry(vm.Account).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(vm);
}

Database items getting deleted when referencing them multiple times

I am creating a simple blogging application to get .NET MVC 4 down and I am having a problem. Everything works except for when I try to tag a blog using an array of strings for each blog like so:
public class BlogEntry
{
public List<Comment> BlogComments { get; set; }
public virtual List<String> RawTags { get; set; }
public virtual List<Tag> BlogTags { get; set; }
public virtual User Author { get; set; }
public int AuthorId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public DateTime DatePosted { get; set; }
[Key]
public int Id { get; set; }
public bool IsAcceptingComments { get; set; }
public bool IsVisible { get; set; }
public DateTime LastEdited { get; set; }
}
public class Tag
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public int RefCount { get; set; }
}
Upon creating a blog and tagging it, I save tags into the BlogEntry model using this:
[HttpPost]
public int Create(string data)
{
if (data != null)
{
BlogEntry newBlog = JsonConvert.DeserializeObject<BlogEntry>(data);
newBlog.Author = Session["user"] as User;
newBlog.AuthorId = newBlog.Author.Id;
newBlog.IsVisible = true;
newBlog.IsAcceptingComments = true;
newBlog.LastEdited = DateTime.Now;
newBlog.DatePosted = DateTime.Now;
newBlog.BlogTags = new List<Tag>();
foreach (String s in newBlog.RawTags)
{
// First check to see if the tag already exists
Tag check = Db.Tags.Where(m => m.Name == s).FirstOrDefault();
if (check != null)
{
check.RefCount++;
newBlog.BlogTags.Add(check);
Db.Tags.Attach(check);
Db.Entry(check).State = System.Data.Entity.EntityState.Modified;
Db.SaveChanges();
}
else
{
// Create a new tag
Tag newTag = new Tag();
newTag.Name = s;
newTag.RefCount = 1;
newBlog.BlogTags.Add(newTag);
Db.Tags.Add(newTag);
}
}
Db.BlogEntries.Add(newBlog);
Db.SaveChanges();
return newBlog.Id;
}
return -1;
}
First I do a check to see if a tag already exists.. If it does, I try to add the same tag, check to the newBlog object. I would have thought that this would just save a reference to this Tag object in the DbSet, however, if I create multiple blogs posts with the tag "html" and then run a query to see what blogs have the html tag, only the most recently tagged blog retains this value.... What can I do so that I can have multiple BlogEntry objects with the same Tag object in the database?

I don't have my dev machine in front of me right now, so this is just a guess, but I figure it's better than making you wait until tomorrow...
I don't think you need the last 3 lines in your if(check!=null) and in fact, I wonder if they aren't messing you up:
Db.Tags.Attach(check);
Db.Entry(check).State = System.Data.Entity.EntityState.Modified;
Db.SaveChanges();
You shouldn't need to attach because you got it from the Db object already, so it should already be being tracked. This means you don't need to change the state and as for the SaveChanges, you are going to do that below.
And now another disclaimer: I've done some work with Entity Framework (version 6, if you want to know), but not with MVC, so it may be different, but my understanding is that it is better to create a new DbContext for each set of instructions, rather than having a class variable that just tracks running changes. I'm not sure if that is what you are doing or not, but it sort of looks that way from this code sample. Assuming that is relevant in MVC, you may consider creating a new DbContext (Db) at the top of your create method.
Let me know how it goes--if this doesn't help, I'll delete this answer.

First you would have to update the Tag class so that it can track its registered blog entries itself. Here the BlogEntry and Tag classes have a many-to-many relationship. So the Tag class would look like below:
public class Tag
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public int RefCount { get; set; }
public virtual List<BlogEntry> BlogEntries { get; set; } // MODIFICATION
}
Now you have to add the blog entry to all of its tags for back referencing to meet your query in an easy way. Look for the modifications I have made in the for-loop below:
foreach (String s in newBlog.RawTags)
{
// First check to see if the tag already exists
Tag check = Db.Tags.Where(m => m.Name == s).FirstOrDefault();
if (check != null)
{
check.RefCount++;
check.BlogEntries.Add(newBlog); // MODIFICATION
newBlog.BlogTags.Add(check);
Db.Tags.Attach(check);
Db.Entry(check).State = System.Data.Entity.EntityState.Modified;
Db.SaveChanges();
}
else
{
// Create a new tag
Tag newTag = new Tag();
newTag.Name = s;
newTag.RefCount = 1;
newTag.BlogEntries = new List<BlogEntry>(); // MODIFICATION
newTag.BlogEntries.Add(newBlog); // MODIFICATION
newBlog.BlogTags.Add(newTag);
Db.Tags.Add(newTag);
}
}
To see what blogs have the html tag, you just have to query on the Tag class and search through the BlogEntries to get the desired blogs. Good luck!