Contact me if you have any problem or question. (email: [email protected])

You can check the code-project article for reading and downloading a step-by-step sample project demonstration. (http://www.codeproject.com/Articles/1131322/Automatically-Define-the-State-of-All-Entities-in)

NuGet Packages

Install-Package EntityGraphOperations

The problem – Tons of repetitive code segments

Usually we find ourselves writing very similar codes for defining the state of entities. Normally, the procedure is as follows:

• Determine which properties are needed for defining existence of the entity in the database (this could be primary key properties or unique key properties).
• If the result is null then the entity must be inserted.
• If the result is not null and if a change has occurred in any part of the entity, then the entity must be updated.
• If we have a collection of entities, then we need to compare it with the ones in the database and delete those which do not exist in the collection anymore.

and so on …

Additional explanation about why sometimes we need unique key properties in addition to the primary key properties

Say we have Phone entity which has some properties: ID, Digits, Prefix …

ID is auto-generated primary key. We do not want to insert same phone number to the table with a different ID. So Digits and Prefix properties are unique together. This situation is forcing us to take into consideration the followings:

If Id is 0, and there is not any corresponding entity in the database with the specified Digits and prefix, then it must be inserted. Otherwise, if a change has occurred, then it must be updated and so on…

Now, let’s do the same things all over again for a different entity graph. Again, and again…

The solution – Use EntityGraphOperations for Entity Framework Code First

Features:

• Automatically define state of all entities
• Update only those entities which have changed
• Fluent API style mapping of special entity configurations
• Let the user manually manage graph after automatically determining state of all entities

The example:

Let’s say I have got a Person object. Person could have many phones, a Document and he/she could have a spouse.

public class Person
{
     public int Id { get; set; }
     public string FirstName { get; set; }
     public string LastName { get; set; }
     public string MiddleName { get; set; }
     public int Age { get; set; }
     public int DocumentId {get; set;}
   
     public virtual ICollection<Phone> Phones { get; set; }
     public virtual Document Document { get; set; }
     public virtual PersonSpouse PersonSpouse { get; set; }
}

I want to determine the state of all entities which are included in the graph.

context.InsertOrUpdateGraph(person)
       .After(entity =>
       {
            // Delete missing phones.
            entity.HasCollection(p => p.Phones)
               .DeleteMissingEntities();
               
            // Delete if spouse is not exist anymore.
            entity.HasNavigationalProperty(m => m.PersonSpouse)
                  .DeleteIfNull();
       });

Also as you remember unique key properties could play role while defining the state of Phone entity. For such special purposes we have ExtendedEntityTypeConfiguration<> class, which inherits from EntityTypeConfiguration<>. If we want to use such special configurations then we must inherit our mapping classes from ExtendedEntityTypeConfiguration<>, rather than EntityTypeConfiguration<>. For example:

public class PhoneMap: ExtendedEntityTypeConfiguration<Phone>
    {
        public PhoneMap()
        {
             // Primary Key
             this.HasKey(m => m.Id);
              …
             // Unique keys
             this.HasUniqueKey(m => new { m.Prefix, m.Digits });
        }
    }

That’s all.