Questions tagged [entity]

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What is the best practice for API endpoints for an entity?

I don't know if the title is reflecting the question correctly, but I can explain more than write a good title. If I have a database that has (employees, departments, orders, etc...), and have ...
5
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1answer
2k views

Is it normal for a Domain Model not to have an ID?

After reading the book; I understood the following: 1) Entities should implement equality and compare by ID. 2) Value Objects should implement equality and compare by all properties in the class. I ...
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2answers
80 views

Sql: Pre inserting relational entities vs the "lazy creation" of the entities

I have the following entities in my database (it's simplified): Student (id) StudentCourse (id, student_id, course_id) Course (id) Lesson (id) LessonCourse (id, lesson_id, course_id) ...
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1answer
10k views

Shall the Database in a sequence diagram be represented as actor or boundary?

I'm designing a system made of a web application and database. I use the <<Entity>> - <<Control>> - <<Boundary>> stereotypes in my UML diagram. In the following ...
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1answer
153 views

Filling in background information in terms of DDD

Recently, I asked about my difficulties in finding the boundaries of aggregates here and I recently reinterpreted it and rid it of business features and now it sounds like this: In many sources, ...
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2answers
3k views

How to design the aggregate boundaries?

I would like to write an application something like ecommerce. And you know that in similar applications products could have different properties and features. To simulate such an opportunity I've ...
4
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1answer
895 views

DDD - Domain Modelling association between aggregates

I have a bit of a mental block when trying to model my scenario whilst practicing DDD. The problem appears to be around 2 entities you would consider to be aggregate roots. I feel these aggregate ...
1
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1answer
2k views

Service layer with DTO

I'm refactoring my desing to use a service layer - however I'm confused about how you would pass arguments, when it's only allowed to update certain fields of the entity. For instance I have some ...
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4answers
526 views

The Open/Closed Principle, how does it work for adding entities?

I'm not even sure how to ask this, but here goes: Let's say I have a Web application that incorporates Teachers, Courses and Students in such a way that I can do things like this (pseudocode): ...
3
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4answers
4k views

ASP.NET Projects using too much .NET Boilerplate Libraries / Code

I am very puzzled with the obsession that many people seem to have with using Microsoft frameworks. I have seen several tutorials and projects (both open and closed source) that seem to utilize all of ...
1
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1answer
5k views

How to represent and validate website URLs for a JPA entity

I have an application that will allow the user to enter and store (in a DB) a website URL for a company. The only requirement (as of now) beyond entry of the website URL is to validate that the URL is ...
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2answers
2k views

How to really decide whether an entity is weak or not

This is the ER diagram example from the Wikipedia. Here they have marked the Orders entity as a strong entity. As I understand a weak entity is an entity which cannot exist without a corresponding ...
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4answers
101 views

Is there a term for an entity that represents another known missing entity?

I am working on a project where I am importing data from 3rd party sources. Often certain data is missing (usually older data), which is detectable from the data that I do have. Obviously I cannot ...
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2answers
101 views

Dealing with entities customization

I suppose every project that is considered as huge and diversed into a lot of parts (admin side, widgets, API, website with a lot of stuff and management) can finally encounter that it is actually ...
0
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1answer
1k views

Should I extend an entity object with a separate class?

I have a simple entity class in my C# application that I would like to add additional properties to for use in the app. These properties will not be persisted to the database. In the past, I was ...
5
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2answers
1k views

A more data oriented design approach to Entity Component System

I'm creating my first c++ game engine project (for learning purposes) and in it I've attempted to implement an entity/component system utilizing some data oriented design principles while also not ...
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2answers
5k views

How to create new aggregate root in CQRS?

How should we create new aggregate roots in cqrs architecture? In this example I want to create new aggregate root AR2 that holds reference to first one AR1. I'm creating AR2 using AR1 method as ...
4
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2answers
2k views

is it bad practice that controller call domain objects(entities) direclty instead of service?

is it bad practice that controller call the methods of domain objects directly instead of service? to explain more: I figure out that in good design controllers call service and service use Domain ...
2
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1answer
951 views

Configuring entity behavior DDD

In one of the products I work with we have an aggregation root with a lot of domain logic, and now I have a requirement to make one small piece of behavior configurable. To give an example, let's say ...
5
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1answer
364 views

Should I retrieve related entities from the parent entity or the service layer?

Let's say I have a three tier application structure, with Presentation, Service and Data layers. The data layer is managed by an ORM and has two models/entities, Show and Episode, with a one-to-many ...
2
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2answers
1k views

How chose a design for an event system

I'm working on a Entity Component System for learning purpose. I made major changes with my design so I was wondering if I could pick a better design for my event system. The purpose of the event ...
4
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1answer
3k views

Java DDD project organization

Just wanted to hear opinions on this kind of project structure in java for one DDD project: com.some.namespace application services = (app services that talk to repositories and domain model) ...
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1answer
2k views

MVVM Model vs. DDD Entity

I have just stepped into the Domain Driven Design paradigm but I have one question: How is an MVVM Model different from a DDD Entity? What are the differences between these two?
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2answers
329 views

How to correctly model aggregation with respect to persistence?

When modeling bigger domain entities you will probably have some kind of relation between these entities. These relations will usually result in entities referencing different entities. If i am not ...
1
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1answer
768 views

ERD for a Lab Database

Question: In a database for a clinical reference lab a specimen, when taken, triggers a test order (for testing obviously) creation.If that test order produces a failure, the specimen is given a new ...
2
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2answers
3k views

How to avoid circular reference in OOP Javascript?

I have a problem while working with entity framework in JavaScript. I have two classes Table and Column Class Table { Columns: Column[] } Class Column { Parent: Table } Everything works fine until ...
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1answer
588 views

Correctness of ERD diagrams

I am new to database modeling.Here is a problem I was trying to solve: Information about movies,stars and studios.Movies are shot in studios that own them.A movie is shot in only one studio.Stars are ...
4
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1answer
611 views

When mapping from a database, do OOP objects (entities) need to store the database values in attributes?

When it comes to OOP where an external database is being read from and written to, is it necessary to have attributes/properties within the objects to store the data? Or is it enough to simply read ...
1
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1answer
4k views

c# extending a entity framework class

I have a Entity Framework class that was derived from the database layout. I was wondering if there was any problems by extending the class by creating another cs file and using the same public ...
10
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2answers
455 views

Should well-known business ID of an entity be represented with a dedicated type in DDD/OOP?

In practical terms it means using an custom (immutable) class over a string or some other primitive type. Examples: Publishing: International Standard Book Number. Finance: International Securities ...
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1answer
586 views

VO to Entity Conversion

In our application we have multiple layers. UI -> This can be JSP/ JSON result of the API Controllers -> as in MVC Services -> perform single business operation per service DAOs -> Data Access ...
84
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13answers
13k views

Do objects in OOP have to represent an entity?

Does an object have to represent an entity? By an entity I mean something like a Product, Motor, a ParkingLot etc, a physical, or even a clear-cut non-physical conceptual object -- something that ...
0
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1answer
129 views

What should this interface contain?

I am creating a schema for Doctrine but first I'm creating interfaces, abstract classes (models) which will be extended by the entities. I have a PresentationInterface which contain getter and ...
10
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2answers
6k views

Are the Repository Pattern and Active Record pattern compatible?

Currently I am developing a webapp where I have defined models implementing the Active Record pattern. Each model also is defined by an interface that specifies the Entity properties and makes it easy ...
2
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2answers
215 views

Controlled access to list of entities vs get/set access in domain model

When designing a domain, either way of following approaches can be used to access list of child entities inside a parent entity. 1. Get/Set Following approach is straight forward and simple to ...
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0answers
74 views

What is the best way to create DTOs from entities and update entities from DTOs in a layered architecture? [duplicate]

Option 1: At first I would make a call to my service layer, which served as an API for my core domain, to get a domain object or a list of domain objects and then pass them into the assembler which ...
10
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2answers
16k views

Repository pattern vs DAO managing Entities

I am new to concepts like DAO, DAL and Domain Driven Design. In the end I want to decouple the persistence layer (mysql database) from my business objects and logic in a web application. I liked the ...
2
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1answer
2k views

Producing JSON objects from JPA entities in REST API

I have a REST service producing JSON and consuming JSON. A lot of this are simple CRUD operations. My initial idea was to simply use the DAOs directly in the controller: @ResponseBody() @...
2
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2answers
610 views

DDD - If an object is saved as a whole to the database, is it per definition an entity, or is it still possible that it is a value object?

I'm learning about Domain Driven Design and struggling with the question if a particular object should be handled as entity or value object. All possible surname prefixes are kept in a database table....
0
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2answers
579 views

Entity design for a blackjack game - should I make Card an entity?

I am creating a simple blackjack game backed by database In my Card is public class Card{ private Face face; private Suit suit; //setters.. getters } where face and suit are enums I have an ...
1
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1answer
94 views

Allow entities owned by one user to be referenced by other users' entities

I am working on an Asp.NET MVC web application. I have the following (simplified) entities: public class Course { public int Id { get; set; } public string Name { get; set; } public ...
0
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1answer
494 views

Are there two type of associations between objects or are there just different representations?

I've been spending some time on 're-tuning' some of my OOP understanding, and I've come up against a concept that is confusing me. Lets say I have two objects. A user object and an account object. ...
3
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2answers
2k views

Entity Component System Coupling

Lately I've been working on a small personal project which is basically an Entity Component System framework with autoupdated Systems. While I have a pretty good idea on the way the framework should ...
2
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3answers
437 views

Repository matrix pattern?

I'm trying really hard to refactor some of my legacy code in the project using best practices and design patterns + DDD so I'd love some feedback on an issue I'm currently having. Let's assume that I ...
0
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1answer
2k views

Applying DDD to a simple app with a configuration twist

I’m using the light-weight PHP Fat-Free Framework as a base to form a simple MVC based app with DDD philosophy for the Model layer. I’m aware that DDD is most suitable or enterprise solutions and that ...
2
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1answer
202 views

How can I define shared text entities in XHTML files?

I have an XHTML document that defines several text entities in its internal DTD. I want these entities to be available in other XHTML documents without having to cut and paste the internal DTD ...
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3answers
2k views

Should entities be accessible from all layers of an application? [closed]

I am googling this issue now for weeks, but cannot find a good discussion. It boils down to this: As POCO entities used in a dbContext are in fact a definition of the database, shouldn't they be ...
5
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2answers
3k views

"Clean Code": How to organize named queries?

Few days ago I started to read Robert C. Martin "Clean Code" book and it encouraged me to look more detailed at my code. After I opened eclipse I saw this: entityManager.createNamedQuery("...
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1answer
341 views

Relationships in a Chen ERD

I am working on a Chen ERD to model our organizations merchandise. Our central entity is a Style. We have supplemental entities of Color and Season. I am defining our assortment as the ...
10
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3answers
5k views

Entity Framework Entities - Some Data From Web Service - Best Architecture?

We are currently using Entity Framework as an ORM across a few web applications, and until now, it has suited us well as all our data is stored in a single database. We are using the repository ...