I'm using the entity framework and I have some properties which are common to all entities:
CreatedByUserName
CreatedDateTime
LastModifiedByUserName
LastModifiedDatetime
So currently I'm saving a new property and I'm having to go like this:
_db.ProjectApprovals.Add(projectApproval);
projectApproval.CreatedByUserName = "Dev";
projectApproval.CreatedDateTime = DateTime.Now;
_db.SaveChanges();
As you can imagine having to do:
projectApproval.CreatedByUserName = "Dev";
projectApproval.CreatedDateTime = DateTime.Now;
for all entities every save is a pain. I was thinking of wrapping the save and then I could do it in there. The problem is how would I know which entities in the context had been added or modified.
First of all you must define shared interface for all your entities implementing these properties:
public interface IEntity
{
string CreatedByUserName { get; set; }
DateTime CreatedDateTime { get; set; }
...
}
Implement this interface in your entities and override SaveChanges method in your derived ObjectContext.
public override int SaveChanges(SaveOptions saveOptions)
{
var entries = this.ObjectStateManager
.GetObjectStateEntries(EntityState.Added | EntityState.Modified)
.Where(x => !x.IsRelationship && x.Entity is IEntity);
foreach (var entry in entiries)
{
var entity = entry.Entity as IEntity;
if (entry.State == EntityState.Added)
{
...
}
else
{
...
}
}
return SaveChagnes(saveOptions);
}
Related
I have an EF6 setup against a sql server db with about 60 tables in it.
I have entities for each table. What i'm trying to do is run the same method against a set of these entities that will be known at runtime.
The method is a qa/qc routine that does some data check on particular fields that are assured to be in each table.
I guess what i want to do is make the entity a parameter to the method so i can call it consecutive times.
I would also want to make a set of entities to pass as the parameter.
something like this:
List<string> entList = new List<string>(){"Table1","Table2","Table3"};
foreach (entName in entList)
{
//create an entity with the string name
//call myQAQCMethod with the entity
}
MyQAQCMethod (entity SomeEntity)
{
//run against this entity
doQAQC(SomeEntity);
}
Can this be done? Is it a job for reflection?
EDIT
using (var context = new Context())
{
var results = context.EntityAs.Where(a => a.Prop1 == e.Prop1)
.Where(a => a.Prop2 == e.Prop2)
.Select(a => new
{
APropertyICareAbout = a.Prop1,
AnotherPropertyICareAbout = a.Prop2
}).ToArray();
}
is precisely want i want to do. The thing is I want to avoid typing this loop 60 times. I think i'm looking for a way to "feed" a set of entities to this single method.
Also, thank you very much for helping me. I'm learning a lot.
You need to abstract an interface (entity framework won't even notice):
interface IQaQcable
{
int CommonInt { get; set; }
string CommonString { get; set; }
}
public class EntityA : IQaQcable
{
public int Id { get; set; }
public int CommonInt { get; set; }
public string CommonString { get; set; }
// other properties and relations
}
public class EntityB : IQaQcable
{
public int Id { get; set; }
public int CommonInt { get; set; }
public string CommonString { get; set; }
// other properties and relations
}
// in some unknown utility class
void MyQaQcMethod<T>(T entity) where T : IQaQcable
{
doSomethingWithIQaQcableProperties(entity.CommonInt, entity.CommonString);
}
// in some unknown test class
void Test()
{
var entities = new List<IQaQcable> { new EntityA(), new EntityB() };
foreach (var e in entities)
MyQaQcMethod(e);
}
Now, you could extract a base class from which each derives that actually implements the CommonInt and CommonString properties for each entity needing them, but that can get kind of tricky with Table-Per-Type/Table-Per-Hierarchy, so I'd start with this, and then consider introducing either an abstract or concrete base class as an improvement.
EDIT
Maybe your looking for something simpler than I first thought, based on your last comment.
Let's give ourselves what the DbContext for this might look like:
class Context : DbContext
{
public virtual DbSet<EntityA> EntityAs { get; set; }
public virtual DbSet<EntityB> EntityBs { get; set; }
}
So, it could just be that you wish to do this:
using (var context = new Context())
{
var results = context.EntityAs.Where(a => a.Prop1 == e.Prop1)
.Where(a => a.Prop2 == e.Prop2)
.Select(a => new
{
APropertyICareAbout = a.Prop1,
AnotherPropertyICareAbout = a.Prop2
}).ToArray();
}
Keeping in mind, if there is some set of properties in common across entity classes, you could still do something like the following:
IEnumerable<T> MyQaQcMethod(IQueryable<T> entities, T referenceEntity) where T : IQaQcAble
{
return entities.Where(e => SomePredicate(e, referenceEntity));
}
void Test()
{
using (var context = new Context())
{
// EntityA implements IQaQcAble
var resultsForA = MyQaQcMethod(context.EntityAs, defaultEntity).ToArray();
// so does EntityB, so can call with either
var resultsForB = MyQaQcMethod(context.EntityBs, defaultEntity).ToArray();
}
}
Keep in mind, to avoid modifying the generated entity classes, you could implement the interface members — and the interface — in a separate source file using partial classes. E.g.
// IQaQcAble.cs
internal interface IQaQcAble
{
int CommonInt { get; set; }
string CommonString { get; set; }
}
// a class whose existing property names match the interface
public partial class EntityA : IQaQcAble
{
int IQaQcAble.CommonInt
{
get { return CommonInt; }
set { CommonInt = value; }
}
string IQaQcAble.CommonString
{
get { return CommonString; }
set { CommonString = value; }
}
}
// a class whose property names differ
public partial class EntityB : IQaQcAble
{
int IQaQcAble.CommonInt
{
get { return SomeOtherInt; }
set { SomeOtherInt = value; }
}
string IQaQcAble.CommonString
{
get { return SomeOtherInt.ToString(); }
set { SomeOtherInt = Convert.ToInt32(value); }
}
}
I am currently using EF4.3 and Code First. Creation of my objects works (via my views - just using the auto-generated Create), but when I attempt to edit an object, it does not save any changes that, utlimately, tie back to my navigation properties. I have been reading on relationships, but I don't understand how to tell my context that the relationship has changed.
Here is some example code of my implementation.
#* Snippet from my view where I link into my ViewModel. *#
<div class="row">
<div class="editor-label">
#Html.LabelFor(model => model.ManagerID)
</div>
<div class="editor-field">
#Html.DropDownListFor(model => model.ManagerID, ViewBag.Manager as SelectList, String.Empty)
#Html.ValidationMessageFor(model => model.ManagerID)
</div>
</div>
Here is my Controller implementation (POST of my Edit):
[HttpPost]
public ActionResult Edit(ProjectViewModel projectViewModel)
{
if (ModelState.IsValid)
{
Project project = new Project();
project.ProjectID = projectViewModel.ProjectID;
project.Name = projectViewModel.Name;
project.ProjectManager = repository.GetUser(projectViewModel.ManagerID);
repository.InsertOrUpdateProject(project);
repository.Save();
return RedirectToAction("Index");
}
ViewBag.Manager = new SelectList(repository.GetUsers(), "UserID", "FullName", projectViewModel.ManagerID);
return View(projectViewModel);
}
Within my Project object:
public class Project
{
public int ProjectID { get; set; }
[Required]
public string Name { get; set; }
// Navigation Properties
public virtual User Manager { get; set; }
}
Here is the corresponding method from the repository (where my context resides):
public void InsertOrUpdateProject(Project project)
{
if (program.ProjectID == default(int))
{
context.Projects.Add(project);
}
else
{
context.Entry(project).State = EntityState.Modified;
}
}
Just to be clear, this does work to update my properties, but it does not update my navigation properties (in this case, Manager). Appreciate any help.
Setting the state to Modified only marks scalar properties as modified, not navigation properties. You have several options:
A hack (you won't like it)
//...
else
{
var manager = project.Manager;
project.Manager = null;
context.Entry(project).State = EntityState.Modified;
// the line before did attach the object to the context
// with project.Manager == null
project.Manager = manager;
// this "fakes" a change of the relationship, EF will detect this
// and update the relatonship
}
Reload the project from the database including (eager loading) the current manager. Then set the properties. Change tracking will detect a change of the manager again and write an UPDATE.
Expose a foreign key property for the Manager navigation property in your model:
public class Project
{
public int ProjectID { get; set; }
[Required]
public string Name { get; set; }
public int ManagerID { get; set; }
public virtual User Manager { get; set; }
}
Now ManagerID is a scalar property and setting the state to Modified will include this property. Moreover you don't need to load the Manager user from the database, you can just assign the ID you get from your view:
Project project = new Project();
project.ProjectID = projectViewModel.ProjectID;
project.Name = projectViewModel.Name;
project.ManagerID = projectViewModel.ManagerID;
repository.InsertOrUpdateProject(project);
repository.Save();
There are several options here, I will list 3 of them:
Option 1: Using GraphDiff
*This needs the Configuration.AutoDetectChangesEnabled of your context set to true.
Just install GraphDiff with NuGet
Install-Package RefactorThis.GraphDiff
Then
using (var context = new Context())
{
var customer = new Customer()
{
Id = 12503,
Name = "Jhon Doe",
City = new City() { Id = 8, Name = "abc" }
};
context.UpdateGraph(customer, map => map.AssociatedEntity(p => p.City));
context.Configuration.AutoDetectChangesEnabled = true;
context.SaveChanges();
}
For more details about GraphDiff look here.
Option 2: Find and Edit
Searching your entity with EF to track it to the context. Then edit the properties.
*This needs the Configuration.AutoDetectChangesEnabled of your context set to true.
var customer = new Customer()
{
Id = 12503,
Name = "Jhon Doe",
City = new City() { Id = 8, Name = "abc" }
};
using (var context = new Contexto())
{
var customerFromDatabase = context.Customers
.Include(x => x.City)
.FirstOrDefault(x => x.Id == customer.Id);
var cityFromDataBase = context.Cities.FirstOrDefault(x => x.Id == customer.City.Id);
customerFromDatabase.Name = customer.Name;
customerFromDatabase.City = cityFromDataBase;
context.Configuration.AutoDetectChangesEnabled = true;
context.SaveChanges();
}
Option 3: Using a scalar property
In a matter of performance this is the best way, but it mess your class with database concerns. Because you will need to create a scalar (primitive type) property to map the Id.
*In this way there is no need to set the Configuration.AutoDetectChangesEnabled to true. And also you won't need to do a query to the database to retrieve the entities (as the first two options would - yes GraphDiff does it behind the scenes!).
var customer = new Customer()
{
Id = 12503,
Name = "Jhon Doe",
City_Id = 8,
City = null
};
using (var contexto = new Contexto())
{
contexto.Entry(customer).State = EntityState.Modified;
contexto.SaveChanges();
}
I am not sure exactly what you mean by navigation properties? Do you mean like a foreign key relationship? If so then try the following data annotation:
public class Project
{
public int ProjectID { get; set; }
[Required]
public string Name { get; set; }
[ForeignKey("YourNavigationProperty")]
public virtual UserManager { get; set; }
}
Update your EF Context, and see what happens?
UPDATE
public class Project
{
public int ProjectID { get; set; }
[Required]
public string Name { get; set; }
[ForeignKey("ManagerId")]
public ManagerModel UserManager { get; set; }
}
public class ManagerModel
{
[Key]
public int ManagerId { get; set; }
public String ManagerName { get; set; }
}
See if that works?
How can I detect changes of ICollection<> properties (many-to-many relationships)?
public class Company
{
...
public virtual ICollection<Employee> Employees { get; set; }
}
using (DataContext context = new DataContext(Properties.Settings.Default.ConnectionString))
{
Company company = context.Companies.First();
company.Employees.Add(context.Employees.First());
context.SaveChanges();
}
public class DataContext : DbContext
{
public override int SaveChanges()
{
return base.SaveChanges();
// Company's entity state is "Unchanged" in this.ChangeTracker
}
}
Here is how to find all the changed many-to-many relationships. I've implemented the code as extension methods:
public static class IaExtensions
{
public static IEnumerable<Tuple<object, object>> GetAddedRelationships(
this DbContext context)
{
return GetRelationships(context, EntityState.Added, (e, i) => e.CurrentValues[i]);
}
public static IEnumerable<Tuple<object, object>> GetDeletedRelationships(
this DbContext context)
{
return GetRelationships(context, EntityState.Deleted, (e, i) => e.OriginalValues[i]);
}
private static IEnumerable<Tuple<object, object>> GetRelationships(
this DbContext context,
EntityState relationshipState,
Func<ObjectStateEntry, int, object> getValue)
{
context.ChangeTracker.DetectChanges();
var objectContext = ((IObjectContextAdapter)context).ObjectContext;
return objectContext
.ObjectStateManager
.GetObjectStateEntries(relationshipState)
.Where(e => e.IsRelationship)
.Select(
e => Tuple.Create(
objectContext.GetObjectByKey((EntityKey)getValue(e, 0)),
objectContext.GetObjectByKey((EntityKey)getValue(e, 1))));
}
}
Some explanation. Many-to-many relationships are represented in EF as Independent Associations, or IAs. This is because the foreign keys for the relationship are not exposed anywhere in the object model. In the database the FKs are in a join table, and this join table is hidden from the object model.
IAs are tracked in EF using "relationship entries". These are similar to the DbEntityEntry objects you get from the DbContext.Entry except that they represent a relationship between two entities rather than an entity itself. Relationship entries are not exposed in the DbContext API, so you need to drop down to ObjectContext to access them.
A new relationship entry is created when a new relationship between two entities is created, for example by adding an Employee to the Company.Employees collection. This relationship is in the Added state.
Likewise, when a relationship between two entities is removed, then the relationship entry is put into the Deleted state.
This means that to find changed many-to-many relationships (or actually any changed IA) we need to find added and deleted relationship entries. This is what the GetAddedRelationships and GetDeletedRelationships do.
Once we have relationship entries, we need to make sense of them. For this you need to know a piece of insider knowledge. The CurrentValues property of an Added (or Unchanged) relationship entry contains two values which are the EntityKey objects of the entities at either end of the relationship. Likewise, but annoyingly slightly different, the OriginalValues property of a Deleted relationship entry contains the EntityKey objects for the entities at either end of the deleted relationship.
(And, yes, this is horrible. Please don’t blame me—it is from well before my time.)
The CurrentValues/OriginalValues difference is why we pass a delegate into the GetRelationships private method.
Once we have the EntityKey objects we can use GetObjectByKey to get the actual entity instances. We return these as tuples and there you have it.
Here’s some entities, a context, and an initializer, I used to test this. (Note—testing was not extensive.)
public class Company
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Employee> Employees { get; set; }
public override string ToString()
{
return "Company " + Name;
}
}
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Company> Companies { get; set; }
public override string ToString()
{
return "Employee " + Name;
}
}
public class DataContext : DbContext
{
static DataContext()
{
Database.SetInitializer(new DataContextInitializer());
}
public DbSet<Company> Companies { get; set; }
public DbSet<Employee> Employees { get; set; }
public override int SaveChanges()
{
foreach (var relationship in this.GetAddedRelationships())
{
Console.WriteLine(
"Relationship added between {0} and {1}",
relationship.Item1,
relationship.Item2);
}
foreach (var relationship in this.GetDeletedRelationships())
{
Console.WriteLine(
"Relationship removed between {0} and {1}",
relationship.Item1,
relationship.Item2);
}
return base.SaveChanges();
}
}
public class DataContextInitializer : DropCreateDatabaseAlways<DataContext>
{
protected override void Seed(DataContext context)
{
var newMonics = new Company { Name = "NewMonics", Employees = new List<Employee>() };
var microsoft = new Company { Name = "Microsoft", Employees = new List<Employee>() };
var jim = new Employee { Name = "Jim" };
var arthur = new Employee { Name = "Arthur" };
var rowan = new Employee { Name = "Rowan" };
newMonics.Employees.Add(jim);
newMonics.Employees.Add(arthur);
microsoft.Employees.Add(arthur);
microsoft.Employees.Add(rowan);
context.Companies.Add(newMonics);
context.Companies.Add(microsoft);
}
}
Here’s an example of using it:
using (var context = new DataContext())
{
var microsoft = context.Companies.Single(c => c.Name == "Microsoft");
microsoft.Employees.Add(context.Employees.Single(e => e.Name == "Jim"));
var newMonics = context.Companies.Single(c => c.Name == "NewMonics");
newMonics.Employees.Remove(context.Employees.Single(e => e.Name == "Arthur"));
context.SaveChanges();
}
I cant give you the exact code for your situation, but I can tell you your situation will be simplified ten fold by having a joiner table inbetween Employees and Company just to break up the many to many relationship.
class DemoUser
{
[TitleCase]
public string FirstName { get; set; }
[TitleCase]
public string LastName { get; set; }
[UpperCase]
public string Salutation { get; set; }
[LowerCase]
public string Email { get; set; }
}
Suppose i have demo-class as written above, i want to create some custom annotations like LowerCase,UpperCase etc so that its value gets converted automatically. Doing this will enable me to use these annotations in other classes too.
As Ladislav implied, this is two questions in one.
Assuming you follow the recipe for creating attributes in Jefim's link, and assuming you're calling those created attribute classes "UpperCaseAttribute", "LowerCaseAttribute", and "TitleCaseAttribute", the following SaveChanges() override should work in EF 4.3 (the current version as of the time of this answer post).
public override int SaveChanges()
{
IEnumerable<DbEntityEntry> changedEntities = ChangeTracker.Entries().Where(e => e.State == System.Data.EntityState.Added || e.State == System.Data.EntityState.Modified);
TextInfo textInfo = Thread.CurrentThread.CurrentCulture.TextInfo;
changedEntities.ToList().ForEach(entry =>
{
var properties = from attributedProperty in entry.Entity.GetType().GetProperties()
where attributedProperty.PropertyType == typeof (string)
select new { entry, attributedProperty,
attributes = attributedProperty.GetCustomAttributes(true)
.Where(attribute => attribute is UpperCaseAttribute || attribute is LowerCaseAttribute || attribute is TitleCaseAttribute)
};
properties = properties.Where(p => p.attributes.Count() > 1);
properties.ToList().ForEach(p =>
{
p.attributes.ToList().ForEach(att =>
{
if (att is UpperCaseAttribute)
{
p.entry.CurrentValues[p.attributedProperty.Name] = textInfo.ToUpper(((string)p.entry.CurrentValues[p.attributedProperty.Name]));
}
if (att is LowerCaseAttribute)
{
p.entry.CurrentValues[p.attributedProperty.Name] = textInfo.ToLower(((string)p.entry.CurrentValues[p.attributedProperty.Name]));
}
if (att is TitleCaseAttribute)
{
p.entry.CurrentValues[p.attributedProperty.Name] = textInfo.ToTitleCase(((string)p.entry.CurrentValues[p.attributedProperty.Name]));
}
});
});
});
return base.SaveChanges();
}
You can override the SaveChanges method in your EF context (if you use default code-generation just write a partial class). Something like the following:
public partial class MyEntityContext
{
public override int SaveChanges(SaveOptions options)
{
IEnumerable<ObjectStateEntry> changedEntities =
this.ObjectStateManager.GetObjectStateEntries(
System.Data.EntityState.Added | System.Data.EntityState.Modified);
// here you can loop over your added/changed entities and
// process the custom attributes that you have
return base.SaveChanges(options);
}
}
is there any way of going through all the new/modified entities and setting their, inserted_at, updated_at fields?
With ObjectStateManager I can get a list of those entities but could not find a way of setting the entity property values.
foreach (var item in db.ObjectStateManager.GetObjectStateEntries(EntityState.Added))
{
System.Data.Objects.DataClasses.EntityObject entity = (System.Data.Objects.DataClasses.EntityObject)(item.Entity);
// now how can I set its .inserted_at to DateTime.Now
}
here is my current solution
public interface IUpdateTrack
{
DateTime? updated_at { get; set; }
Guid? updated_by { get; set; }
}
public interface IInsertTrack
{
DateTime? inserted_at { get; set; }
Guid? inserted_by { get; set; }
}
implement the interface in the partial class
public partial class crm_customer : BaseDB.IInsertTrack, BaseDB.IUpdateTrack
in the repository class
public void Save()
{
foreach (var item in db.ObjectStateManager.GetObjectStateEntries(EntityState.Added))
{
System.Data.Objects.DataClasses.EntityObject entity = (System.Data.Objects.DataClasses.EntityObject)(item.Entity);
if (item.Entity is BaseDB.IInsertTrack)
{
IInsertTrack insert_track = (IInsertTrack)(item.Entity);
insert_track.inserted_at = DateTime.Now;
insert_track.inserted_by = BaseDB.SessionContext.Current.ActiveUser.UserUid;
}
}
foreach (var item in db.ObjectStateManager.GetObjectStateEntries(EntityState.Modified))
{
if (item.Entity is BaseDB.IUpdateTrack)
{
IUpdateTrack update_track = (IUpdateTrack)(item.Entity);
update_track.updated_at = DateTime.Now;
update_track.updated_by = BaseDB.SessionContext.Current.ActiveUser.UserUid;
}
}
I would like a solution that does not require implementing the interface for each class in the model, its error prone, you might forget to implement this interfaces for some classes.
I am using EF4 using database-first approach.
Yes, there is a perfect way to accomplish this in Entity Framework 4.0, Thanks to Julia Lerman for pointing out this nice trick.
using System.Data.Common;
using System.Data.Metadata.Edm;
...
var entries = from e in db.ObjectStateManager.GetObjectStateEntries(
EntityState.Added | EntityState.Modified)
where e.Entity != null
select e;
foreach (var entry in entries) {
var fieldMetaData = entry.CurrentValues.DataRecordInfo.FieldMetadata;
FieldMetadata updatedAtField = fieldMetaData
.Where(f => f.FieldType.Name == "updated_at").FirstOrDefault();
if (updatedAtField.FieldType != null) {
string fieldTypeName = updatedAtField.FieldType.TypeUsage.EdmType.Name;
if (fieldTypeName == PrimitiveTypeKind.DateTime.ToString()) {
entry.CurrentValues.SetDateTime(updatedAtField.Ordinal,
DateTime.Now);
}
}
}
You can then call this code from within the SavingChanges event to be sure that any
updated_at field is automatically updated.
By the way, the System.Data.Metadata.Edm namespace gives you access to
the PrimitiveTypeKind class.