I am trying to remove all references followed by adding them back from a list of disconnected objects.
using(var scope = new TransactionScope())
{
_autoIncidentService.AddNewCompanyVehicles(
autoIncidentModel.CompanyVehiclesInvolved.Where(v => v.Id == 0));
_autoIncidentService.ClearCollections(autoIncidentModel.Id);
_autoIncidentService.Update(autoIncidentModel);
scope.Complete();
}
return Json(ResponseView);
The ClearCollections removes items references. The GetAutoIncident includes the collection.
public void ClearCollections(int id)
{
var autoIncident = GetAutoIncident(id);
foreach (var vehicle in autoIncident.CompanyVehiclesInvolved.ToArray())
{
autoIncident.CompanyVehiclesInvolved.Remove(vehicle);
}
db.SaveChanges();
}
When I try to update the entity right after the ClearCollections method it fails.
The relationship between the two objects cannot be defined because they are attached to different ObjectContext objects.
I am using a singleton to get the DbContext so there shouldn't be any situation where the context is different. It is being stored in the HttpContext.Current.Items.
The update method is as follows:
public override void Update(AutoIncidentModel model)
{
var data = GetData(model.Id);
Mapper.CreateMap<AutoIncidentModel, AutoIncident>()
.ForMember(m => m.CompanyVehiclesInvolved, opt => opt.ResolveUsing(m =>
{
var ids = m.CompanyVehiclesInvolved.Select(v => v.Id);
return db.Vehicles.Where(v => ids.Contains(v.Id)).ToList();
}));
Mapper.Map(model, data);
db.SaveChanges();
}
Obviously, I am missing something important here. Do the entites from my ResolveUsing method need to somehow be associated with the parent entity or is automapper overwriting the property (CompanyVehiclesInvolved) and causing a problem?
Related
I am writing a generic querying method in Entity Framework 6, based off of this helpful article. Here's how it looks:
public static T QueryEagerLoad<T>(Expression<Func<T, bool>> match) where T : class
{
using (var databaseContext = new ClearspanDatabaseContext())
{
databaseContext.Configuration.LazyLoadingEnabled = false;
T retrievedObject = databaseContext.Set<T>().SingleOrDefault(match);
return retrievedObject;
}
}
I'm attempting to eagerly load any related entities, so I include disable to configuration variable LazyLoadingEnabled. While it loads the object, it does not load the related entities, per my view in the debugger. Why would this be? Am I missing something? I should note that I'm using Npgsql. Thanks in advance.
See Mikael Östberg's answer to this question. To use a generic method for querying with eager loading, it seems necessary to inject the includes. Here's how the generic method shaped up:
public static T Query<T>(Expression<Func<T, bool>> match, List<Expression<Func<T, object>>> includes) where T : class
{
using (var databaseContext = new ClearspanDatabaseContext())
{
var dataSet = databaseContext.Set<T>(); // Get the relevant DataSet
T retrievedObject = includes.Aggregate( // Eagerly load the passed navigation properties
dataSet.AsQueryable(),
(current, include) => current.Include(include)
).SingleOrDefault(match); // Find exactly one or zero matches
return retrievedObject;
}
}
And an example of a call that injects the properties to eagerly load (the includes parameter in the generic method above):
public static Lumber GetLumber(int databaseId)
{
Expression<Func<Lumber, object>> lengthProperty = (lumber => lumber.Length);
Expression<Func<Lumber, object>> thicknessProperty = (lumber => lumber.Thickness);
Expression<Func<Lumber, object>> widthProperty = (lumber => lumber.Width);
List<Expression<Func<Lumber, object>>> lumberNaviationProperties = new List<Expression<Func<Lumber, object>>>() { lengthProperty, thicknessProperty, widthProperty };
Lumber retrievedLumber = DatabaseOperations.Query<Lumber>((lumber => lumber.DatabaseId == databaseId), lumberNaviationProperties);
return retrievedLumber;
}
I need to update all fields except property1 and property2 for the given entity object.
Having this code:
[HttpPost]
public ActionResult Add(object obj)
{
if (ModelState.IsValid)
{
context.Entry(obj).State = System.Data.EntityState.Modified;
context.SaveChanges();
}
return View(obj);
}
How to change it to add an exception to obj.property1 and obj.property2 for not being updated with this code?
Let's assume that you have a collection of the properties to be excluded:
var excluded = new[] { "property1", "property2" };
With EF5 on .NET 4.5 you can do this:
var entry = context.Entry(obj);
entry.State = EntityState.Modified;
foreach (var name in excluded)
{
entry.Property(name).IsModified = false;
}
This uses a new feature of EF5 on .NET 4.5 which allows a property to be set as not modified even after it has been previously set to modified.
When using EF 4.3.1 or EF5 on .NET 4 you can do this instead:
var entry = context.Entry(obj);
foreach (var name in entry.CurrentValues.PropertyNames.Except(excluded))
{
entry.Property(name).IsModified = true;
}
You can't define such an exception. You can however mark single properties as modified:
context.Entry(obj).Property(o => o.Property3).IsModified = true;
context.Entry(obj).Property(o => o.Property4).IsModified = true;
// etc.
Note that setting IsModified to false is not supported once you have marked the state of the whole entity to Modified.
For your purpose I would actually prefer to load the entity from the database and then update it using normal change tracking:
var objInDB = context.Objects.Single(o => o.Id == obj.Id);
obj.Property1 = objInDB.Property1;
obj.Property2 = objInDB.Property2;
context.Entry(objInDB).CurrentValues.SetValues(obj);
context.SaveChanges();
Note that only changed properties will be saved by default by Automatic Detect changes.
See EF 6 and EF Core articles
This question was already nicely answered, but I wanted to provide an extension method for anyone who would like to use it.
This code was developed for EF 4.3.1
//You will need to import/use these namespaces
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
//Update an entity object's specified columns, comma separated
//This method assumes you already have a context open/initialized
public static void Update<T>(this DbContext context, T entityObject, params string[] properties) where T : class
{
context.Set<T>().Attach(entityObject);
var entry = context.Entry(entityObject);
foreach(string name in properties)
entry.Property(name).IsModified = true;
context.SaveChanges();
}
Usage Example
using (FooEntities context = new FooEntities())
{
FooEntity ef = new FooEntity();
//For argument's sake say this entity has 4 columns:
// FooID (PK), BarID (FK), Name, Age, CreatedBy, CreatedOn
//Mock changes
ef.FooID = 1;
ef.Name = "Billy";
ef.Age = 85;
context.Update<FooEntity>(ef, "Name", "Age"); //I only want to update Name and Age
}
This is an update that works for .net CORE and maybe can help someone who needs a generic solucion and wants to exclude some properties base on different conditions.
I'm using reflection to iterate through the properties and update base on its property value, in this case, as example, i'm excluding the null properties.
public virtual TEntity Update(TEntity entity)
{
dbSet.Attach(entity);
dbContext.Entry(entity).State = EntityState.Modified;
var entry = dbContext.Entry(entity);
Type type = typeof(TEntity);
PropertyInfo[] properties = type.GetProperties();
foreach (PropertyInfo property in properties)
{
if (property.GetValue(entity, null) == null)
{
entry.Property(property.Name).IsModified = false;
}
}
dbContext.SaveChanges();
return entity;
}
The answers above (most of them) use DbContext. For those who is using ObjectContext these solutions arent accessible.
Here is solution for ObjectContext strictly (EF5 .NET 4.5):
ctx.AddObject("ENTITYNAME", item);
ctx.ObjectStateManager.ChangeObjectState(item, EntityState.Modified);
var entry = ctx.ObjectStateManager.GetObjectStateEntry(item);
entry.RejectPropertyChanges("PROPERTY_TO_EXCLUDE");
I'm using EF4. I'm adding a series of new entities from a list of DTOs, and I'm not saving changes until after all of them are added. I'm wanting to set the IDs of the DTOs to what the new entities' IDs are. How on earth do I do this? Does EF provide a mechanism for this?
With a single entity I would do this:
public void InsertMyDto(MyDto a_dto)
{
var newEntity = new MyEntity
{
Name = a_dto.Name,
Type = a_dto.Type.ToString(),
Price = a_dto.Price
};
_dataContext.MyEntities.AddObject(newEntity);
_dataContext.SaveChanges();
a_dto.ID = newEntity.ID;
}
This works fine, but what do I do in this case?
public void InsertMyDtos(IEnumerable<MyDto> a_dtos)
{
foreach (var myDto in a_dtos)
{
var newEntity = new MyEntity
{
Name = myDto.Name,
Type = myDto.Type.ToString(),
Price = myDto.Price
};
// Does some validation logic against the database that might fail.
_dataContext.MyEntities.AddObject(newEntity);
}
_dataContext.SaveChanges();
// ???
}
I want to save all at once, because I have validation work (not shown above) that is done against the database and fails before it gets to SaveChanges, and if it fails I want it to fail as a whole transaction (i.e. rollback).
I don't think that EF can help you here. It even can't help you for a single instance which forces you to write a_dto.ID = newEntity.ID. The counterpart of this code for multiple entites is to keep track of the pairs of dtos and new entities:
public void InsertMyDtos(IEnumerable<MyDto> a_dtos)
{
Dictionary<MyDto, MyEntity> dict = new Dictionary<MyDto, MyEntity>();
foreach (var myDto in a_dtos)
{
var newEntity = new MyEntity
{
Name = myDto.Name,
Type = myDto.Type.ToString(),
Price = myDto.Price
};
dict.Add(myDto, newEntity);
// Does some validation logic against the database that might fail.
_dataContext.MyEntities.AddObject(newEntity);
}
_dataContext.SaveChanges();
foreach (var item in dict)
item.Key.ID = item.Value.ID; // Key is MyDto, Value is MyEntity
}
Is there a nice way to execute code when an entity is being saved to the database using EF/code-first?
I have a Url property on many of my entities. If a URL has not been given explicitly, I would like to calculate one as the object is persisted, eg.:
public void OnModelSaving()
{
// If a URL has not been specified, generate one from the name.
if (this.Url == null)
{
this.Url = Helper.GenerateSafeUrl(this.Title);
}
}
Ideally, I'd like all this code to be stored inside the Model, but since I don't have an EF-owned base/partial class, I suspect if it's possible, I'd have to register/wire it up elsewhere. Question is - is it possible, and if so, how do I wire it up?
The only way is to override SaveChanges method on your context, iterate through changed entities and check the Url
public override int SaveChanges()
{
var entities = ChangeTracker.Entries()
.Where(e => e.State == EntityState.Added ||
e.State == EntityState.Modified)
.Select(e => e.Entity())
.OfType<YourEntityType();
foreach (var entity in entities)
{
entity.Url = ...;
}
return base.SaveChanges();
}
If you have many entity types providing Url you can try to define interface with that Url implemented by all that entity types and in OfType use that interface.
I am new to MVC, and am really struggling with what I seems like it should be a very common scenario. I'm using MVC2 RTM, and the Entity Framework for my model objects.
What I have working:
An edit view for a parent object that contains a collection of child objects. The form displays all the editable fields for the parent, and iterates through and displays all editable fields for all the associated child objects (in the same view). I am able to successfully handle the edit action in my controller, but run into issues when I try to bind values in the form collection to the EF model objects.
The problem:
In my controller function, when I call TryUpdateModel and pass the parent object, I get the following error:
"The EntityCollection has already been initialized. The InitializeRelatedCollection method should only be called to initialize a new EntityCollection during deserialization of an object graph."
I have seen a lot of other posts from people struggling with similar issues, but have not found a solution. Is this not possible without building a custom model binder? If anyone has a working example, I would greatly appreciate it. For some reason, I am able to iterate through the child collection and successfully execute TryUpdateModel on the child objects, but when I call it on the parent, the error above is thrown. Ideally I'd like to call it once for the parent, and have the whole object tree update from the form.
Here's the controller code:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(int id, FormCollection formValues)
{
EFEntities ef = new EFEntities();
ParentObject parent = ef.ParentObjects.SingleOrDefault(p => p.ID == id);
if (ModelState.IsValid)
{
int i = 0;
foreach (child in parent.ChildObjects)
{
//this works fine
TryUpdateModel(child, "ChildObjects[" + i + "]");
i++;
}
//this blows up
if (TryUpdateModel(parent))
{
ef.SaveChanges();
return RedirectToAction("Details", new { id = parent.ID });
}
}
return View(parent);
}
Thanks for this question, even though it wasn't answered it gave me my answer. The best thing I can find to do is this (using your example):
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(int id, FormCollection formValues)
{
EFEntities ef = new EFEntities();
ParentObject parent = ef.ParentObjects.SingleOrDefault(p => p.ID == id);
if (ModelState.IsValid)
{
int i = 0;
foreach (child in parent.ChildObjects)
{
//this works fine
TryUpdateModel(child, "ChildObjects[" + i + "]");
i++;
}
//exclude the collections and it won't blow up...
if (TryUpdateModel(parent, "Parent", null, new string[] {"ChildObjects"}))
{
ef.SaveChanges();
return RedirectToAction("Details", new { id = parent.ID });
}
}
return View(parent);
}
Ultimately I found a more elegant solution, but never came back to post it. Here it is - sorry for the delay:
if (ModelState.IsValid)
{
if (TryUpdateModel(parent, new[] "prop1", "prop2", "prop3" })) //specify parent-only properties to include
{
if (TryUpdateModel(parent.ChildObjects, "ChildObjects"))
{
_ef.SaveChanges();
return RedirectToAction("Details", new { id = parent.ID }) }
}
}
return View(parent);
I'm converting this code from a real life app, so my apologies for any typos.