i'm using SQLite Provider with Entity Frame work in .Net 4.5
conferControlEntities.Configuration.LazyLoadingEnabled = true;
conferControlEntities.Configuration.ProxyCreationEnabled = true;
conferControlEntities.Configuration.AutoDetectChangesEnabled = true;
conferControlEntities.Configuration.ValidateOnSaveEnabled = true;
and i am also using inheritance in the Entity Framework
so i cannot use the include in the query as i can't include the derived objects navigation property
so i have fillNavigationPropty method in Poco classes which will make a call to the Navigation properties and try to fill them
but whenever i check it will be null
using (var context = GetContext(false,true))
{
var queryable = context.Delegates.Where(i => i.ParentId == id);
foreach (var entity in queryable)
{
entity.FillNavigationProperties();
list.Add(WrapperFactory.Create(entity) as TU);
}
return new ObservableCollection<TU>(list);
}
POCO Example
public class TempPOCO
{
public virtual AnotherPCOCCLassTYpe NavigationProperty1{get;set;}
public void FillNavigationProperties()
{
var tempcall = NavigationProperty1;
}
}
Related
I am tinkering with WebAPI to create a generic implementation for entity framework. I am able to implement most of the methods just fine, but am finding PUT to be tricky in non-trivial cases. The implementation most commonly found online works for simple entities:
[HttpPut]
[ActionName("Endpoint")]
public virtual T Put(T entity)
{
var db = GetDbContext();
var entry = db.Entry(entity);
entry.State = EntityState.Modified;
var set = db.Set<T>();
set.Attach(entity);
db.SaveChanges();
return entity;
}
...but does not delete or update child lists:
public class Invoice
{
...
public virtual InvoiceLineItem {get; set;} //Attach method doesn't address these
}
In an MVC Controller, you could simply use "UpdateModel" and it would add/update/delete children as needed, however that method is not available on ApiController. I understand that some code would be necessary to get the original item from the database, and that it would need to use Include to get the child lists, but can't quite figure out the best way to replicate UpdateModel's functionality:
[HttpPut]
[ActionName("Endpoint")]
public virtual T Put(T entity)
{
var db = GetDbContext();
var original = GetOriginalFor(entity);
//TODO: Something similar to UpdateModel(original), such as UpdateModel(original, entity);
db.SaveChanges();
return original;
}
How can I implement UpdateModel OR somehow implement Put in such a way that it will handle child lists?
The routine dont validate entity, but fill the pre-existent entity.
protected virtual void UpdateModel<T>(T original, bool overrideForEmptyList = true)
{
var json = ControllerContext.Request.Content.ReadAsStringAsync().Result;
UpdateModel<T>(json, original, overrideForEmptyList);
}
private void UpdateModel<T>(string json, T original, bool overrideForEmptyList = true)
{
var newValues = JsonConvert.DeserializeObject<Pessoa>(json);
foreach (var property in original.GetType().GetProperties())
{
var isEnumerable = property.PropertyType.GetInterfaces().Any(t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof(IEnumerable<>));
if (isEnumerable && property.PropertyType != typeof(string))
{
var propertyOriginalValue = property.GetValue(original, null);
if (propertyOriginalValue != null)
{
var propertyNewValue = property.GetValue(newValues, null);
if (propertyNewValue != null && (overrideForEmptyList || ((IEnumerable<object>)propertyNewValue).Any()))
{
property.SetValue(original, null);
}
}
}
}
JsonConvert.PopulateObject(json, original);
}
public void Post()
{
var sample = Pessoa.FindById(12);
UpdateModel(sample);
}
I have this method in my SurveyController class:
public ActionResult AddProperties(int id, int[] propertyids, int page = 1)
{
var survey = _uow.SurveyRepository.Find(id);
if (propertyids == null)
return GetPropertiesTable(survey, page);
var repo = _uow.PropertySurveyRepository;
propertyids.Select(propertyid => new PropertySurvey
{
//Setting the Property rather than the PropertyID
//prevents the error occurring later
//Property = _uow.PropertyRepository.Find(propertyid),
PropertyID = propertyid,
SurveyID = id
})
.ForEach(x => repo.InsertOrUpdate(x));
_uow.Save();
return GetPropertiesTable(survey, page);
}
The GetPropertiesTable redisplays Properties but PropertySurvey.Property is marked virtual and I have created the entity using the new operator, so a proxy to support lazy loading was never created and it is null when I access it. When we have access direct to the DbContext we can use the Create method to explicitly create the proxy. But I have a unit of work and repository pattern here. I guess I could expose the context.Create method via a repository.Create method and then I need to remember to use that instead of the new operator when I add an entity . But wouldn't it be better to encapsulate the problem in my InsertOrUpdate method? Is there some way to detect that the entity being added is not a proxy when it should be and substitute a proxy? This is my InsertOrUpdate method in my base repository class:
protected virtual void InsertOrUpdate(T e, int id)
{
if (id == default(int))
{
// New entity
context.Set<T>().Add(e);
}
else
{
// Existing entity
context.Entry(e).State = EntityState.Modified;
}
}
Based on the answer supplied by qujck. Here is how you can do it without having to employ automapper:
Edited to always check for proxy - not just during insert - as suggested in comments
Edited again to use a different way of checking whether a proxy was passed in to the method. The reason for changing the technique is that I ran into a problem when I introduced an entity that inherited from another. In that case an inherited entity can fail the entity.e.GetType().Equals(instance.GetType() check even if it is a proxy. I got the new technique from this answer
public virtual T InsertOrUpdate(T e)
{
DbSet<T> dbSet = Context.Set<T>();
DbEntityEntry<T> entry;
if (e.GetType().BaseType != null
&& e.GetType().Namespace == "System.Data.Entity.DynamicProxies")
{
//The entity being added is already a proxy type that supports lazy
//loading - just get the context entry
entry = Context.Entry(e);
}
else
{
//The entity being added has been created using the "new" operator.
//Generate a proxy type to support lazy loading and attach it
T instance = dbSet.Create();
instance.ID = e.ID;
entry = Context.Entry(instance);
dbSet.Attach(instance);
//and set it's values to those of the entity
entry.CurrentValues.SetValues(e);
e = instance;
}
entry.State = e.ID == default(int) ?
EntityState.Added :
EntityState.Modified;
return e;
}
public abstract class ModelBase
{
public int ID { get; set; }
}
I agree with you that this should be handled in one place and the best place to catch all looks to be your repository. You can compare the type of T with an instance created by the context and use something like Automapper to quickly transfer all of the values if the types do not match.
private bool mapCreated = false;
protected virtual void InsertOrUpdate(T e, int id)
{
T instance = context.Set<T>().Create();
if (e.GetType().Equals(instance.GetType()))
instance = e;
else
{
//this bit should really be managed somewhere else
if (!mapCreated)
{
Mapper.CreateMap(e.GetType(), instance.GetType());
mapCreated = true;
}
instance = Mapper.Map(e, instance);
}
if (id == default(int))
context.Set<T>().Add(instance);
else
context.Entry(instance).State = EntityState.Modified;
}
I have the following generic code to update a disconnected entity:
public T UpdateItem(T entity)
{
this._dbSet.Attach(entity);
this._dbContext.Entry(entity).State = System.Data.EntityState.Modified;
this._dbContext.SaveChanges();
return entity;
}
If my entity contains navigation properties, those do not get attached and set to modified. Is there a way I can change this generic method to attach and set to modified, all navigation properties as well?
You can do it with reflection. Here's an extension method to find all the related collections. If all of your Entities implement some standard interface you'll be able to make a similar method to find the non collection navigation properties (that implement your interface).
public static class ContextExtensions
{
public static IEnumerable<IEnumerable<dynamic>> GetCollections(this object o)
{
var result = new List<IEnumerable<dynamic>>();
foreach (var prop in o.GetType().GetProperties())
{
if (typeof(IEnumerable<dynamic>).IsAssignableFrom(prop.PropertyType))
{
var get = prop.GetGetMethod();
if (!get.IsStatic && get.GetParameters().Length == 0)
{
var enumerable = (IEnumerable<dynamic>)get.Invoke(o, null);
if (enumerable != null) result.Add(enumerable);
}
}
}
return result;
}
}
This should add the current objects navigation properties
var collections = entity.GetCollections();
foreach (var collection in collections)
{
foreach (var r in collection)
{
if (_this._dbSet.Entry(r).State == System.Data.EntityState.Detached)
{
this._dbSet.Attach(r);
this._dbContext.Entry(r).State = System.Data.EntityState.Modified;
}
}
}
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 have a many-to-many relationship between two entities - Media and MediaCollection. I want to check if a certain Media already exists in a collection. I can do this as follows:
mediaCollection.Media.Any(m => m.id == mediaId)
However, mediaCollection.Media is an ICollection, so to me this looks like it will have to retrieve every Media in the collection from the database just to make this check. As there could be many media in a collection, this seems very inefficient. I'n thinking that I should use a method of IQueryable, but I can't see how to do this for many-to-many relationships.
How can I check for the existence of the relationship without retrieving the whole collection?
EDIT
I am generating the EF data model from my database, then using the built in VS POCO T4 templates to generate my data context and entity classes. I think the problem is that the generated code does not return EntityCollection for the navigation properties, but instead ObjectSet. ObjectSet implements IQueryable, but does not expose a CreateSourceQuery() method.
Here is a stripped down version of the relevant lines from the context:
public partial class Entities : ObjectContext
{
public const string ConnectionString = "name=Entities";
public const string ContainerName = "Entities";
#region Constructors
public Entities()
: base(ConnectionString, ContainerName)
{
this.ContextOptions.LazyLoadingEnabled = true;
}
public Entities(string connectionString)
: base(connectionString, ContainerName)
{
this.ContextOptions.LazyLoadingEnabled = true;
}
public Entities(EntityConnection connection)
: base(connection, ContainerName)
{
this.ContextOptions.LazyLoadingEnabled = true;
}
#endregion
#region ObjectSet Properties
public ObjectSet<MediaCollection> MediaCollections
{
get { return _mediaCollections ?? (_mediaCollections = CreateObjectSet<MediaCollection>("MediaCollections")); }
}
private ObjectSet<MediaCollection> _mediaCollections;
// snipped many more
#endregion
}
And here is a stripped down version of the class for the MediaCollection entity:
public partial class MediaCollection
{
#region Primitive Properties
// snipped
#endregion
#region Navigation Properties
public virtual ICollection<Medium> Media
{
get
{
if (_media == null)
{
var newCollection = new FixupCollection<Medium>();
newCollection.CollectionChanged += FixupMedia;
_media = newCollection;
}
return _media;
}
set
{
if (!ReferenceEquals(_media, value))
{
var previousValue = _media as FixupCollection<Medium>;
if (previousValue != null)
{
previousValue.CollectionChanged -= FixupMedia;
}
_media = value;
var newValue = value as FixupCollection<Medium>;
if (newValue != null)
{
newValue.CollectionChanged += FixupMedia;
}
}
}
}
private ICollection<Medium> _media;
private void FixupMedia(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.NewItems != null)
{
foreach (Medium item in e.NewItems)
{
if (!item.MediaCollections.Contains(this))
{
item.MediaCollections.Add(this);
}
}
}
if (e.OldItems != null)
{
foreach (Medium item in e.OldItems)
{
if (item.MediaCollections.Contains(this))
{
item.MediaCollections.Remove(this);
}
}
}
}
// snip
#endregion
}
And finally, here is the FixupCollection that the template also generates:
public class FixupCollection<T> : ObservableCollection<T>
{
protected override void ClearItems()
{
new List<T>(this).ForEach(t => Remove(t));
}
protected override void InsertItem(int index, T item)
{
if (!this.Contains(item))
{
base.InsertItem(index, item);
}
}
}
You can do that but you need a context for that:
bool exists = context.Entry(mediaCollection)
.Collection(m => m.Media)
.Query()
.Any(x => x.Id == mediaId);
Edit:
If you are using ObjectContext API with proxied POCOs instead of DbContext API the former sample will not work. You can try this:
context.ContextOptions.LazyLoadingEnabled = false;
bool exists = ((EntityCollection<Media>)mediaCollection.Media).CreateSourceQuery()
.Any(x => x.Id == mediaId);
context.ContextOptions.LazyLoadingEnabled = true;
So it seems that the built in VS POCO T4 template does not generate anything equivalent to CreateSourceQuery(). No matter! We can code it ourselves. If you add the following code at to the context's .tt file and regenerate:
public ObjectQuery<T> CreateNavigationSourceQuery<T>(object entity, string navigationProperty)
{
var ose = ObjectStateManager.GetObjectStateEntry(entity);
var rm = ObjectStateManager.GetRelationshipManager(entity);
var entityType = (System.Data.Metadata.Edm.EntityType)ose.EntitySet.ElementType;
var navigation = entityType.NavigationProperties[navigationProperty];
var relatedEnd = rm.GetRelatedEnd(navigation.RelationshipType.FullName, navigation.ToEndMember.Name);
return ((dynamic)relatedEnd).CreateSourceQuery();
}
then we can check for the existence of a many-to-many as follows:
var exists = _context.CreateNavigationSourceQuery<Medium>(mediaCollection, "Media")
.Any(m => m.Id == medium.Id);
Props to Rowan's answer on Using CreateSourceQuery in CTP4 Code First for this one.
Try,
mediaCollection.CreateSourceQuery()
.Any(....
CreateSourceQuery will create IQueryable for the association.