constraints

I have the following entity class in my application: <?php namespace ...; // use ... use Doctrine\ORM\Mapping as ORM; use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;; // ... /** * @ORM\Table(name="sc_user") * @ORM\Entity(repositoryClass="...\UserRepository") * @ORM\HasLifecycleCallbacks() * @UniqueEntity(fields={"email", "username"}) */ class User implements UserInterface, \Serializable, EquatableInterface { /** * @var integer $id * * @ORM\Column(name="id", type="integer") * @ORM\Id * @ORM\GeneratedValue(strategy="AUTO") */ private $id; /** * @var string $email * * @ORM\Column

I have a foreign key constraint between tables Sessions and Users. Specifically, Sessions.UID = Users.ID. Sometimes, I want Sessions.UID to be null. Can this be allowed? Any time I try to do this, I get an FK Constraint Violation. Specifically, I'm inserting a row into Sessions via LINQ. I set the Session.User = null; and I get this error: An attempt was made to remove a relationship between a User and a Session. However, one of the relationship's foreign keys (Session.UID) cannot be set to null. However, when I remove the line that nulls the User property, I get this error on my SubmitChanges

Inside IB I have a viewController with a segmentedControl and 2 containerViews. In each containerView I have a tableView. From each tableView I push on a detailView. My auto layout is in IB. Once I pick a segment, I see the corresponding tableView, I pick a cell and the correct detailView gets pushed on the scene. The issue is once the detailView gets pushed on the segmentedControl is still visible. I decided to hide the segmentedControl which works but there is a big empty space there. I tried to programmatically increase the size of detailView's view but it's not expanding. From what I read

I noticed there are 2 kinds of constraints on Odoo ERP. But I want to know what is the difference between _sql_constraints vs _constraints? _sql_constraints = { ('email_uniq', 'unique(email)', ' Please enter Unique Email id.') } _constraints=[ (_check_qty_and_unitprice, u'Qty must be more than 0',['product_qty', 'cost_unit']), ] Bhavesh Odedra _sql_constraints means it will set constraint on postgresql database side. _sql_constraints = [ ('email_uniq', 'unique(email)', ' Please enter Unique Email id.'), ] Where: email_uniq means constraint name, unique(email) means unique is name of constraint

What does where T : somevalue mean? I just saw some code that said where T : Attribute . I think this has something to do with generics but I am not sure what this means or what it is doing. Does anyone know? It is a constraint on a type parameter , meaning that the type T given to a generic class or method must inherit from the class Attribute For example: public class Foo<T> : where T : Attribute { public string GetTypeId(T attr) { return attr.TypeId.ToString(); } // .. } Foo<DescriptionAttribute> bar; // OK, DescriptionAttribute inherits Attribute Foo<int> baz; // Compiler error, int does