Example structure
public class Page
{
public int PageId { get; set; }
public string Prop1 { get; set; }
public string Prop2 { get; set; }
public virtual List<Section> Sections { get; set; }
}
public class Section
{
public int SectionId { get; set; }
public int PageId { get; set; }
public virtual Page Page { get; set; }
public virtual List<Heading> Headings { get; set; }
}
public class Heading
{
public int HeadingId { get; set; }
public int SectionId { get; set; }
public virtual Section Section { get; set; }
}
It's worth noting that my actual structure has more levels than this but this should be enough to explain what I'm trying to achieve.
So I load my Page object I then Clone that object and make some minor changes to the properties of Page i.e. Prop1, Prop2
Page pageFromDb = getPageMethod();
Page clonedPage = pageFromDb.Clone();
clonedPage.Prop1 = clonedPage.Prop1 + " Cloned";
addPageMethod(clonedPage); //Adds the page to db
In the example above clonedPage structure is fine and a new Page is added to the database. However I believe because the Id's of the child objects are set and the relationship of the children is always one to many. The original object pageFromDb will lose all it children as entity framework instead of creating new Section objects for the cloned Page will update the Section.PageId to the newly inserted page.
I believe a fix for this would be to foreach, foreach, etc. and set all the Id's to 0 before inserting then entity framework will create new records foreach object. Is there any easier/better way to clone an object in an entity framework environment.?
In order for Entity Framework to treat the clone as an entire new object graph when persisting the graph, all entities in the graph need to be disconnected from the context in which the root entity was retrieved.
This can be done using the AsNoTracking method on the context.
For example, this will pull a page and associated sections graph from the database and turn off tracking. Effectively this is a clone as if you add this to your Page DbSet and save it will create an entirely new object graph in the database. I.e. a new Page entity and new Section entities accordingly. Note, you wont need to call your Clone method.
var clone = context.Pages
.AsNoTracking()
.Including(pages => pages.Sections)
.Single(...);
context.Pages.Add(clone);
context.SaveChanges(); // creates an entirely new object graph in the database
Try this!
public Page CopyPage(int pageID)
{
using(Context context = new Context())
{
context.Configuration.LazyLoadingEnabled = false;
Page dbPage = context.Pages.Where(p => p.PageId == pageID).Include(s => s.Sections.Select(s => s.Section)).First();
Page page = dbPage.Clone();
page.PageId = 0;
for (int i = 0; i < dbPage .Sections.Count; i++)
page.Sections[i] = new Section
{
SectionId = 0,
PageId = 0,
Page = null,
Headings = dbPage[i].Headings
};
return page;
}
}
public Page Clone()
{
Object page = this.GetType().InvokeMember("", BindingFlags.CreateInstance, null, this, null);
foreach(PropertyInfo propertyInfo in this.GetType().GetProperties())
{
if(propertyInfo.CanWrite)
{
propertyInfo.SetValue(page, propertyInfo.GetValue(this, null), null);
}
}
return page;
}
Related
I am having trouble saving children entities via Entity Framework / ASP Identity. It seems to be adding duplicates of everything that is added.
I have tried using a detached graph of the DrivingLicenceModel by TeamMember.DrivingLicence = null in the TeamMemberModel and then working with a detached graph by looking if there is new or old DrivingLicenceCategories but because DrivingLicence links back to TeamMember it causes TeamMember.DrivingLicenceId to be null as it cannot link back to TeamMember.
I have tried Manually adding the EntityState to the DrivingLicence and DrivingLicenceCategories but when I do that it complains that it cannot save two entities with the same primary key.
I assume this is because they way I am copying the entities but I after a lot of looking I am drawing a blank.
If there anyway to copy from TeamMemberRequestModel to TeamMemberModel and then save without the children trying to create clone copies of themselves?
Models
public class TeamMemberModel : IdentityUser
{
public virtual DrivingLicenceModel DrivingLicence { get; set; }
public void ShallowCopy(TeamMemberRequestModel src)
{
this.DateOfBirth = src.DateOfBirth;
if (src.DrivingLicence != null)
{
if (this.DrivingLicence == null)
{
this.DrivingLicence = new DrivingLicenceModel(src.DrivingLicence);
}
else
{
this.DrivingLicence.ShallowCopy(src.DrivingLicence);
}
}
}
public TeamMemberModel() { }
}
public class DrivingLicenceModel
{
[Key]
public int Id { get; set; }
[ForeignKey("TeamMember")]
public string TeamMemberId { get; set; }
[JsonIgnore]
public TeamMemberModel TeamMember { get; set; }
public virtual List<DrivingLicenceCategoryModel> DrivingLicenceCategories { get; set; }
public DrivingLicenceModel() { }
public DrivingLicenceModel(DrivingLicenceModel src)
{
this.ShallowCopy(src);
}
public void ShallowCopy(DrivingLicenceModel src)
{
this.Id = src.Id;
this.IsFullLicence = src.IsFullLicence;
this.IssueDate = src.IssueDate;
this.ExpiryDate = src.ExpiryDate;
this.IssuingAuthority = src.IssuingAuthority;
this.LicenceNumber = src.LicenceNumber;
this.DrivingLicenceCategories = src.DrivingLicenceCategories;
this.DrivingLicencePoints = src.DrivingLicencePoints;
}
}
public class DrivingLicenceCategoryModel
{
[Key]
public int Id { get; set; }
[ForeignKey("DrivingLicence")]
public int DrivingLicenceId { get; set; }
[JsonIgnore]
public DrivingLicenceModel DrivingLicence { get; set; }
}
public class TeamMemberRequestModel
{
public string Id { get; set; }
public virtual DrivingLicenceModel DrivingLicence { get; set; }
}
Context
public class TIERDBContext : IdentityDbContext<TeamMemberModel, RoleModel, string, IdentityUserLogin, IdentityUserRole, IdentityUserClaim>
{
public TIERDBContext() : base("SARDBConnection") { }
public DbSet<DrivingLicenceModel> DrivingLicences { get; set; }
public DbSet<DrivingLicenceCategoryModel> DrivingLicenceCategories { get; set; }
}
Controller
public async Task<IHttpActionResult> Put(string id, TeamMemberRequestModel teamMember)
{
TeamMemberModel CurrentTeamMember = await this.TIERUserManager.FindByIdAsync(id);
CurrentTeamMember.ShallowCopy(teamMember);
await this.TIERUserManager.UpdateAsync(CurrentTeamMember);
}
you have to create clone property into context class
.
In the context clases you could to use clone method that retiran the entity you send by parameters this duplicarse any entity you pass. Sorry for my english
hope you help
After far to many hours working over this. I have come to an answer. The best way to deal with this is to simply deal with it is to add or attach all entities down the tree.
The controller now attaches all children unless they have an ID of 0, therefore new and uses add instead. Then I use this very useful extension I found here http://yassershaikh.com/c-exceptby-extension-method/ to compare lists to see added and deleted entities in the list. While I don't need the added part as the entity will already be marked to an add state as I use add() it does not harm and I want to use it later with add and delete state changing.
Controller
public async Task<IHttpActionResult> Put(string id, TeamMemberRequestModel teamMember)
{
TIERDBContext IdentityContext = (TIERDBContext)this.TIERUserManager.UserStore().Context;
foreach (DrivingLicenceCategoryModel DrivingLicenceCategory in teamMember.DrivingLicence.DrivingLicenceCategories)
{
if (DrivingLicenceCategory.Id == 0)
{
IdentityContext.DrivingLicenceCategories.Add(DrivingLicenceCategory);
}
else
{
IdentityContext.DrivingLicenceCategories.Attach(DrivingLicenceCategory);
}
}
foreach (DrivingLicencePointModel DrivingLicencePoint in teamMember.DrivingLicence.DrivingLicencePoints)
{
if (DrivingLicencePoint.Id == 0)
{
IdentityContext.DrivingLicencePoints.Add(DrivingLicencePoint);
}
else
{
IdentityContext.DrivingLicencePoints.Attach(DrivingLicencePoint);
}
}
this.DetectAddedOrRemoveAndSetEntityState(CurrentTeamMember.DrivingLicence.DrivingLicenceCategories.AsQueryable(),teamMember.DrivingLicence.DrivingLicenceCategories, IdentityContext);
this.DetectAddedOrRemoveAndSetEntityState(CurrentTeamMember.DrivingLicence.DrivingLicencePoints.AsQueryable(),teamMember.DrivingLicence.DrivingLicencePoints, IdentityContext);
CurrentTeamMember.ShallowCopy(teamMember);
await this.TIERUserManager.UpdateAsync(CurrentTeamMember);
}
I then use a generic that uses ExceptBy to work out what is added and delete from the old team member model to the new team member model.
protected void DetectAddedOrRemoveAndSetEntityState<T>(IQueryable<T> old, List<T> current, TIERDBContext context) where T : class, IHasIntID
{
List<T> OldList = old.ToList();
List<T> Added = current.ExceptBy(OldList, x => x.Id).ToList();
List<T> Deleted = OldList.ExceptBy(current, x => x.Id).ToList();
Added.ForEach(x => context.Entry(x).State = EntityState.Added);
Deleted.ForEach(x => context.Entry(x).State = EntityState.Deleted);
}
It works but it is far from great. It takes two DB queries, getting the original and updating. I just cannot think of any better way to do this.
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.
Goal: to save ViewModel object by Entity Framework. I have UserViewModel object which has list of UnitViewModel. Then, I have a UserAdapter class which converts UserViewModel into Entity Framework User object (see Convert()below how).
Now, my question is how do I convert this list of UnitViewModel to its corresponding Entity Framework Unit list? - Do I have to get each object from DB Context by calling something like context.Units.Where(u=>myListofUnitIDs.Contains(u.UnitID))?
public class UserViewModel
{
public Guid? UserID { get; set; }
public string UserName { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Password { get; set; }
public DateTime? CreateTime { get; set; }
public List<UnitViewModel> UserUnits { get; set; }
}
public class UnitViewModel
{
public Guid UnitID { get; set; }
public string Name { get; set; }
public int? SortIndex { get; set; }
public DateTime CreateTime { get; set; }
public bool Assigned { get; set; }
}
public class UserAdapter
{
public static User Convert(UserViewModel userView)
{
User user;
if (userView.UserID.HasValue)
{
using (var provider = new CoinsDB.UsersProvider())
{
user = provider.GetUser(userView.UserID.Value);
}
}
else
{
user = new User();
}
user.FirstName = userView.FirstName;
user.LastName = user.LastName;
user.Password = StringHelper.GetSHA1(userView.Password);
user.UserName = user.UserName;
user.CreateTime = DateTime.Now;
// Problem here :)
// user.Units = userView.UserUnits;
return user;
}
}
UPDATE: The main concern here is that I have to retrieve each Unit from database to match (or map) it with ViewModel.Unit objects, right? Can I avoid it?
For your information, this operation is called as Mapping mainly. So, you want to map your view model object to the entity object.
For this, you can either use already existed 3rd party library as AutoMapper. It will map properties by reflection which have same name. Also you can add your custom logic with After method. But, this approach has some advantages and disadvantages. Being aware of these disadvantages could help you to decide whether you must use this API or not. So, I suggest you to read some articles about advantages and disadvantages of AutoMapper especially for converting entities to other models. One of such disadvantages is that it can be problem to change the name of one property in the view model in the future, and AutoMapper will not handle this anymore and you won't get any warning about this.
foreach(var item in userView.UserUnits)
{
// get the mapped instance of UnitViewModel as Unit
var userUnit = Mapper.Map<UnitViewModel, UserUnit>(item);
user.Units.Add(userUnit);
}
So, I recommend to write your custom mappers.
For example, I have created a custom library for this and it maps objects lik this:
user.Units = userView.UserUnits
.Select(userUnitViewModel => userUnitViewModel.MapTo<UserUnit>())
.ToList();
And I am implementing these mapping functions as:
public class UserUnitMapper:
IMapToNew<UnitViewModel, UserUnit>
{
public UnitViewModel Map(UserUnit source)
{
return new UnitViewModel
{
Name = source.Name,
...
};
}
}
And then in runtime, I am detecting the types of the objects which will be used during mapping, and then call the Map method. In this way, your mappers will be seperated from your action methods. But, if you want it urgently, of course you can use this:
foreach(var item in userView.UserUnits)
{
// get the mapped instance of UnitViewModel as Unit
var userUnit= new UserUnit()
{
Name = item.Name,
...
};
user.Units.Add(userUnit);
}
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!
I'm using MVC3 with EF4 code-first. I have the following model:
public class Order {
public int ID { get; set; }
[Required]
public float Price { get; set; }
[Required]
public int PayMethodId { get; set; }
public PayMethod PayMethod { get; set; }
public int? SpecificEventId { get; set; }
public SpecificEvent SpecificEvent { get; set; }
public int? SeasonalTicketId { get; set; }
public SeasonalTicket SeasonalTicket { get; set; }
}
When I try to save an Order object with specificEventId = 2 and specificEvent = X, a new SpecificEvent object is created in the DB, even though there's already a specific event X with ID 2 in the DB. When i try with specificEventId = 2 and specificEvent = null I get a data validation error.
What am I doing wrong? I want SpecificEvent and SeasonalTicket to be nullable, and I don't want EF4 to create a new instance of these objects in the DB whenever I save 'Order'.
Update
This is my code for saving Order in the DB:
public void SaveOrder(Order order)
{
Order fromDb = null;
// If editing an existing object.
if ((fromDb = GetOrder(order.ID)) != null)
{
db = new TicketsDbContext();
db.Entry(order).State = System.Data.EntityState.Modified;
db.SaveChanges();
}
// If adding a new object.
else
{
db.orders.Add(order);
db.SaveChanges();
}
}
When I save, I do reach the else clause.
The real question is, where did you get the instance of X from? It appears as though EF has no knowledge of this instance. You either need to fetch the already existing SpecificEvent through EF and use the proxy it returns to set your navigation property, or else tell EF to "attach" X, so that it knows what your intent is. As far as EF knows, it appears, you are trying to send it a new instance with a conflicting Id, so it is properly issuing the error.