EF Core 3.0 supports entity.HasCheckConstraint() now. To take Ryan’s example: protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<SomeTable>(entity => entity.HasCheckConstraint(“CK_SomeTable_SomeColumn”, “[SomeColumn] >= X”); }
Given the table definition: CREATE TABLE webuser( idwebuser SERIAL PRIMARY KEY, … ) Use the mapping: @Entity @Table(name=”webuser”) class Webuser { @Id @SequenceGenerator(name=”webuser_idwebuser_seq”, sequenceName=”webuser_idwebuser_seq”, allocationSize=1) @GeneratedValue(strategy = GenerationType.SEQUENCE, generator=”webuser_idwebuser_seq”) @Column(name = “idwebuser”, updatable=false) private Integer id; // …. } The naming tablename_columname_seq is the PostgreSQL default sequence naming for SERIAL and I recommend that you … Read more
First off, I’m assuming you have read the article “Multithreading and the Entity Framework” on MSDN. Solution #1 is almost certainly the safest from a threading perspective, since you are guaranteeing that only one thread is interacting with the context at any give time. There is nothing inherently wrong with keeping the context around- it … Read more
The definition of these terms is quite ambiguous. You will find different definitions at different places. Entity: An entity represents a single instance of your domain object saved into the database as a record. It has some attributes that we represent as columns in our tables. Model: A model typically represents a real world object … Read more
In Entity Framework 6 the delete action is Remove. Here is an example Customer customer = new Customer () { Id = id }; context.Customers.Attach(customer); context.Customers.Remove(customer); context.SaveChanges();
It is theoretically correct but SQL server (not Entity framework) doesn’t like it because your model allows single employee to be a member of both First and Second team. If the Team is deleted this will cause multiple delete paths to the same Employee entity. This cannot be used together with cascade deletes which are … Read more
You don’t. This is a very common question. Entities should only know about other entities and not about the entity manager or other high level services. It can be a bit of a challenge to make the transition to this way of developing but it’s usually worth it. What you want to do is to … Read more
I was getting this error and tried a few of the earlier suggestions. Then I checked the Inner Exception and noticed I was getting a simple SQL login failure for the user. Just something else to check.
Creating a new ObjectContext each time does involve ‘some’ overhead. Essentially the overhead involved is copying metadata from a global cache into metadata associated with the specific ObjectContext. This overhead is relatively minor, so often it is not worth worrying about, especially when you consider the extra safety inherent in the using pattern. For me … Read more
The Hibernate configuration file must define the entity classes: <mapping class=”annotations.Users”/> Or you must explicitly add the class to the configuration using configuration.addClass(annotations.Users.class) // Read mappings as a application resourceName // addResource is for add hbml.xml files in case of declarative approach configuration.addResource(“myFile.hbm.xml”); // not hibernateAnnotations.cfg.xml