Questions tagged [entity]
In computer science an entity is an object which has an identity and can be uniquely determined, holds storable information or can be processed. As the term has a very abstract and general meaning prefer to use this tag only in conjunction with other more specific tags.
entity
6,464
questions
903
votes
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answers
1.1m
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How to fix the Hibernate "object references an unsaved transient instance - save the transient instance before flushing" error
I receive following error when I save the object using Hibernate
object references an unsaved transient instance - save the transient instance before flushing
- 13k
349
votes
24
answers
719k
views
PersistentObjectException: detached entity passed to persist thrown by JPA and Hibernate
I have a JPA-persisted object model that contains a many-to-one relationship: an Account has many Transactions. A Transaction has one Account.
Here's a snippet of the code:
@Entity
public class ...
- 11.2k
244
votes
17
answers
334k
views
How to update only one field using Entity Framework?
Here's the table
Users
UserId
UserName
Password
EmailAddress
and the code..
public void ChangePassword(int userId, string password){
//code to update the password..
}
- 5,228
179
votes
18
answers
361k
views
How to set a default entity property value with Hibernate
How do I set a default value in Hibernate field?
- 14.2k
158
votes
14
answers
183k
views
How to delete an object by id with entity framework
It seems to me that I have to retrieve an object before I delete it with entity framework like below
var customer = context.Customers.First(c => c.Id == 1);
context.DeleteObject(customer);
...
- 1,581
137
votes
4
answers
190k
views
What is the difference between persist() and merge() in JPA and Hibernate?
What is the difference between persist() and merge() in Hibernate?
persist() can create a UPDATE & INSERT query, eg:
SessionFactory sef = cfg.buildSessionFactory();
Session session = sef....
- 1,519
135
votes
6
answers
116k
views
What is difference between a Model and an Entity [closed]
I am seeking clarification on the definitions of the terms Entity, Model, DataModel, and ViewModel within the context of software development. Could someone provide a detailed explanation for each of ...
- 27.4k
116
votes
11
answers
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Improving bulk insert performance in Entity framework [duplicate]
I want to insert 20000 records in a table by entity framework and it takes about 2 min. Is there any way other than using SP to improve its performance. This is my code:
foreach (Employees item in ...
- 4,066
110
votes
1
answer
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cascade={"remove"} VS orphanRemoval=true VS ondelete="CASCADE
I tried to gather some information about the following way to delete automatically child entity when a parent entity is deleted. Seems that the most common way is to use one those three annotation: ...
- 1,948
98
votes
4
answers
133k
views
Difference between Entity and DTO
What is the difference between a DTO and an Entity? In details these are my questions:
What fields should the DTOs have? For example my entity classes are:
@Entity
public class MyFirstEntity ...
- 1,181
88
votes
15
answers
96k
views
EF 4.1 exception "The provider did not return a ProviderManifestToken string"
I am trying to replicate an example found on MSDN. I am using ASP.NET and EF 4.1 (CTP?). I've used NuGet to install the EntityFramework package.
I am getting this error: The provider did not return a ...
- 3,948
86
votes
4
answers
74k
views
Differentiating between domain, model, and entity with respect to MVC
Can someone explain these 3 concepts and the differences between them with respect to an MVC framework along with an example. To me these appear almost equivalent, and it seems they are used ...
- 59.1k
86
votes
5
answers
53k
views
Entity Framework - Is there a way to automatically eager-load child entities without Include()?
Is there a way to decorate your POCO classes to automatically eager-load child entities without having to use Include() every time you load them?
Say I have a Class Car, with Complex-typed ...
- 863
81
votes
10
answers
111k
views
What's the HTML character entity for the # sign?
What's the HTML character entity for the # sign? I've looked around for "pound" (which keeps returning the currency), and "hash" and "number", but what I try doesn't ...
- 5,993
74
votes
7
answers
82k
views
How can I disable migration in Entity Framework 6.0 [duplicate]
I'm trying to ignore the "Automatic" migration using Entity Framework 6.0 rc1. My problem is that I don't want this feature right now and every time that my application runs I can see all entity logs ...
- 931
72
votes
6
answers
47k
views
Should I write equals() and hashCode() methods in JPA entities?
I want to check if entity is in a Collection member (@OneToMany or @ManyToMany) of another entity:
if (entity2.getEntities1().contains(entity1)) { }
- 821
70
votes
5
answers
125k
views
SQL JPA - Multiple columns as primary key
If i want severeal Column to make up an ID.
SQL example :
CONSTRAINT [PK_NAME] PRIMARY KEY ([Column1],[Column2],[Column3])
How can i do that with a Jpa Entity class ? through columndefinition ?
...
- 2,365
70
votes
5
answers
34k
views
DDD and MVC: Difference between 'Model' and 'Entity'
I'm seriously confused about the concept of the 'Model' in MVC. Most frameworks that exist today put the Model between the Controller and the database, and the Model almost acts like a database ...
- 3,215
69
votes
5
answers
43k
views
Symfony2 collection of Entities - how to add/remove association with existing entities?
1. Quick overview
1.1 Goal
What I'm trying to achieve is a create/edit user tool. Editable fields are:
username (type: text)
plainPassword (type: password)
email (type: email)
groups (type: ...
- 4,787
66
votes
9
answers
80k
views
How to clone a JPA entity
I have a JPA entity already persisted in the database.
I would like to have a copy of it (with a different id), with some fields modified.
What is the easiest way to do this? Like:
setting it's @Id ...
- 1,528
62
votes
7
answers
90k
views
62
votes
3
answers
49k
views
JPA, How to use the same class (entity) to map different tables?
I have two tables: Ta and Tb. They have exactly the same table structure but different table names.
I try to create one entity class to map the table structures. Some of my common application ...
John
62
votes
12
answers
69k
views
How can I get my database to seed using Entity Framework CodeFirst?
The database is created successfully (as are the tables) but is not seeded. I have spent several hours and read tons of articles but have not been able to get it. Any suggestions?
On a side note, is ...
- 1,696
58
votes
6
answers
87k
views
Entity Framework and Multi threading
We are having some trouble designing our multi-threaded Entity Framework driven application and would like some guidance. We are creating entities on different threads, the entities are added to ...
- 915
54
votes
8
answers
90k
views
Disable caching in JPA (eclipselink)
I want to use JPA (eclipselink) to get data from my database. The database is changed by a number of other sources and I therefore want to go back to the database for every find I execute. I have read ...
- 3,625
54
votes
8
answers
94k
views
Java entity - why do I need an empty constructor?
This might sound stupid to you,
but why do I need to define an empty constructor in my @Entitys?
Every tutorial I saw said : every entity needs an empty constructor.
But Java always give you a default ...
- 2,354
49
votes
5
answers
90k
views
Configure JPA to let PostgreSQL generate the primary key value
So our project use PostgreSQL database and we use JPA for operating the database.
We have created the entities from the database with automatic creator in Netbeans 7.1.2.
After small changes our ...
- 11.2k
48
votes
5
answers
55k
views
nuget retrieving package metadata
An error occurred while retrieving package metadata for
'bootstrap.3.3.5' from source 'nuget.org'.
========== Finished ==========
Where the defect wonder Is site nuget.org may crash or whether ...
- 700
48
votes
7
answers
100k
views
XML Entity for "/"?
So I'm writing some XML generating code, and found that the following attribute value was screwing up the XML formatting:
"Jim/Bob"
So I looked into the XML Entities used as escape sequences and ...
- 916
47
votes
9
answers
93k
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org.postgresql.util.PSQLException: ERROR: column user0_.id does not exist - Hibernate
I have a model class that is mapped to a postgres database using hibernate. My model class is:
@Entity
@Table(name="USER")
public class User {
@Id
@GeneratedValue
@Column(name="id")
...
- 5,331
46
votes
23
answers
259k
views
org.hibernate.MappingException: Unknown entity: annotations.Users
Consider the hierarchy :
And the following classes and xml :
HibernateUtil.java
package annotations;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org....
- 21.7k
46
votes
3
answers
36k
views
JPA entity id - primitive or object type (long or Long)
Should the ID of your Entity be long (primitive type) or Long (object type)?
The ID is the primary key of my table and is never 'null' in the database.
My co-workers suggest to use an Object Type ...
- 10.6k
45
votes
5
answers
118k
views
symfony2 Catchable Fatal Error: Object of class could not be converted to string
I have this Entity defined:
<?php
namespace Apw\BlackbullBundle\Entity;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
/**
* Categories
*
* @ORM\Table()
* @...
- 519
45
votes
4
answers
71k
views
What is the exact meaning of the JPA @Entity annotation?
I am studying JPA in Spring application and I have some doubts related to the @Entity annotation.
So I have a model class like this:
@Entity
@Table(name= “T_CUSTOMER”)
public class Customer {
@...
- 42.3k
43
votes
7
answers
64k
views
JPA thinks I'm deleting a detached object
I've got a DAO that I used to load and save my domain objects using JPA. I finally managed to get the transaction stuff working, now I've got another issue.
In my test case, I call my DAO to load a ...
- 2,700
40
votes
1
answer
41k
views
How to access the entity inside the buildForm method of a form
I'm trying to get the entity inside the own form. I lazy remember a getData() method, but it doesn't exist inside the form, and I can't remember how to use it.
Is there any way to get the entity ...
- 1,970
39
votes
9
answers
103k
views
Generate JPA 2 Entities from existing Database
How can I generate JPA2 compliant @Entity from existing Databases?.
I found this: Question
Still its not clear if JBoss will generate compliant JPA2 and also I would like to know if there is a ...
- 2,234
39
votes
6
answers
106k
views
XML parser error: entity not defined
I have searched stackoverflow on this problem and did find a few topics, but I feel like there isn't really a solid answer for me on this.
I have a form that users submit and the field's value is ...
- 3,621
39
votes
6
answers
43k
views
How to retrieve mapping table name for an entity in JPA at runtime?
Is it possible to determine the native table name of an entity?
If a Table annotation is present it's easy:
entityClass.getAnnotation(Table.class).name()
But what about if no Table annotation is ...
- 1,257
38
votes
4
answers
40k
views
What are the HTML entities for up and down triangles?
I've found the outlined versions, but I want the solid up and down triangles.
Does anyone know these entities?
- 487k
38
votes
3
answers
43k
views
Symfony 2.0 getting service inside entity
Im seraching over and cannot find answer.
I have database role model in my application. User can have a role but this role must be stored into database.
But then user needs to have default role ...
- 1,487
38
votes
1
answer
40k
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Symfony2: get the id of the persisted object
I have two entity: User and Person.
In the entity User I need the id of the associated person: user_id.
When I am creating a new user, I have to create first the person and then the user.
In the ...
- 20k
38
votes
8
answers
34k
views
JPA 2.0: Adding entity classes to PersistenceUnit *from different jar* automatically
I have a maven-built CDI-based Java SE app, which has a core module, and other modules.
Core has the persistence.xml and some entities.
Modules have additional entities.
How can I add the entities to ...
- 46k
36
votes
2
answers
29k
views
check constraint entity framework
IN EF can I add a check constraint so if my CustomerNotes entity has a boolean "FollowUpRequired" property I force user to enter a valid future date in the "FollowUpDate" property?
- 1,414
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votes
5
answers
11k
views
The type 'Company.Model.User' and the type 'Company.Core.Model.User' both have the same simple name of 'User' and so cannot be used in the same model
I have a base entity class MyCompany.Core.Model.User which is to be used for common properties of a User entity:
public class User
{
public string Username { get; set; }
public string ...
- 11.3k
35
votes
3
answers
32k
views
Detached Entity and Managed Entity
What a "detached entity" means?
How is it possible to convert a managed entity to a detached entity during a transaction?
- 387
34
votes
4
answers
61k
views
Efficient way of updating list of entities
I am working on a project which allows the user to edit a list of entities. I map these entities to view models and display them with editor fields. When the user presses the submit button, I go ...
- 6,764
32
votes
2
answers
24k
views
Entity Framework 4.1 InverseProperty Attribute and ForeignKey
I will create two references between Employee and Team entities with foreign keys.
So I defined two entities as follow
public class Employee
{
public int EmployeeId { get; set; }
public ...
- 4,088
32
votes
9
answers
33k
views
Entities equals(), hashCode() and toString(). How to correctly implement them?
I'm implementing equals(), hashCode() and toString() of my entities using all the available fields in the bean.
I'm getting some Lazy init Exception on the frontend when I try to compare the equality ...
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votes
13
answers
33k
views
Could not build ClassFile - ArchiveException
We develop an application with spring, jpa, tomcat, maven, etc.
Locally on my developer machine everything works fine but when we deploy the application on a linux server I get the following ...
- 4,425