orm

问题 I am trying to go trough tutorial of doctrine here is official website. And I got an error in Starting with the Product Entity part. This is what I write to terminal: $ php create_product.php ORM PHP Fatal error: Uncaught Error: Class 'product' not found in /home/vaclav/Server/vssk/VSSK/project/create_product.php:8 Stack trace: #0 {main} thrown in /home/vaclav/Server/vssk/VSSK/project/create_product.php on line 8 回答1: Solved with adding: require_once 'patch_to_your_class/Product.php'; to

问题 I have an entity called User which has set of roles. I also have a Role entity which has set of users.( This is just a practice application for learning purposes.) public class User { private String firstName; private String lastName; @ManyToMany @JoinTable(name="user_role", joinColumns={@JoinColumn(name="user_id")}, inverseJoinColumns={@JoinColumn(name="role_id")}) private Set<Role> roles; //getters setters } public class Role { private String name; @ManyToMany(mappedBy="roles") private Set

问题 I have an entity called User which has set of roles. I also have a Role entity which has set of users.( This is just a practice application for learning purposes.) public class User { private String firstName; private String lastName; @ManyToMany @JoinTable(name="user_role", joinColumns={@JoinColumn(name="user_id")}, inverseJoinColumns={@JoinColumn(name="role_id")}) private Set<Role> roles; //getters setters } public class Role { private String name; @ManyToMany(mappedBy="roles") private Set

问题 I have specific situation where composite primary key of one entity is part of the primary key of another entity. This is case of specialization, but it doesn't matter now. I use Doctrine to generate entities from database, but Doctrine doesn't support composite foreign key as primary key: It is not possible to map entity 'XXXXX' with a composite primary key as part of the primary key of another entity 'YYYYYY#id_xxxxx' Does anyone know solution for this situation? It can be Doctrine solution

问题 I am developing an extension to an existing app which uses sqlalchemy 0.6. The app has sqlalchemy tables created the non-declarative way. I am trying to create in my extension a new table with a foreign key column pointing at the primary key of the main table in the application database and I am creating it declaratively. This all works fine, with the table created once the extension is loaded, and with no complaints at all. My table prints out and demonstrates that new rows have been added

问题 TL;DR: Is it possible to configure Hibernate to delete all child objects using a single delete query? Full Question: I have the following parent/child association defined in Hibernate 5.1: public class Parent { @OneToMany(fetch = FetchType.EAGER, mappedBy = "parent", cascade = CascadeType.REMOVE) private List<Child> children; } public class Child { @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "parent_id", nullable = false) private Parent parent; } When I delete the parent object,

问题 My goal is async loading of related entities using DBContext. Let imagine two projects. The first named MyApp.Domain and contains domain entities. namespace MyApp.Domain { public class PlanPage { public Guid Id { get; set; } } } namespace MyApp.Domain { public class PlanPageDay { public Guid Id { get; set; } public Guid PlanPageId { get; set; } } } The second project named MyApp.Infrastructure.EntityFramework and contains configuration of projection entities to database. It also contains

问题 This question already has answers here : Why is EF generating SQL queries with unnecessary null-checks? (3 answers) Closed 11 months ago . I want to ignore null when the query check the value exist in database table in C# using LINQ and Lambda expression. Below line is checking null as well. When it finds null then ignore it. var nmcExist = db.AspNetUsers.Any(a => a.NMC_Number== model.NMC_Number); 回答1: You might be looking for 2 options: If null , return true .Any(a => a.NMC_Number == null ||

问题 I want to implement an alert messaging system, in a website, that will show a message to either multiple users , multiple groups (different DB representation), or globally to all users. What would a good database relationship for this behavior look like? 回答1: This is where I would start based on the information you've given... A table for the alert messages to be sent out... alerts id unsigned int(P) message text +----+---------------------+ | id | message | +----+---------------------+ | 1 |

问题 I am working on a restaurant app (and new to Django/Python). I want to have a parent class Dish that will contain some counter or ID that increments for every instance of a child class of Dish . The instances are dishes like Pizza, Pasta, etc with different characteristics. I've tried making Dish abstract and non-abstract, but come across different issues each time. This is my Dish class (to make it abstract I tried InheritanceManager(), but ran into complications there that led me to think