Questions tagged [relationships]

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1answer
95 views

Relationship problem between entities

I'm not sure how I should think regarding my database design. I have made this database schema below. And I'm trying to think about the relationship between the entities. I have read through online ...
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1answer
107 views

Best notation to store/read/compute complex relationships

I have created an application in which users and tasks can be entered. A task should be be assigned to one or more users. If more users can do a task, the task should be assigned in such a way that it ...
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2answers
219 views

Relationship between entities in different aggregates and size of aggregate

I read a lot about DDD but few thing are still unclear. At this moment I have two dilemma The size of aggregates. How small could be an aggregate? For example we have: class Car { String colorId ...
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1answer
142 views

What kind of Relations should I have in my E/R Diagram

I am trying to create an Entity/Relationship Chen Diagram for a new APP. Scope is simple enough. I will have multiples types of users login through the same Login Form. What I decided to do... Is ...
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1answer
471 views

UML Use Case Diagrams Relationship - Required / Optional AND independent

I am learning to create Use Case diagrams using the UML specification, but I have a couple of doubts about Use Case relationships which I cannot solve on my own. My question regards two different ...
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1answer
2k views

Designing a REST API resource with a non-unique ID, but unique composite ID

Is it bad for a REST API to have non-unique ID for a child resource? For example, the endpoint is: GET /parent/:parent_name/child/:child_name The :parent_name is unique, but a :child_name is only ...
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2answers
3k views

What is the difference between containment and aggregation relationship in UML?

As it is said in ARLOW, J., AND NEUSTADT, I. UML 2 and the Unified Process, 2nd ed book, there are 7 types of relationship between different objects. Dependency Association Aggregation Composition ...
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1answer
457 views

How to show relationships of the component containing the interface definition when using ball/socket notation in a UML Component Diagram?

I recently found out that I have probably been using ball/socket notation in a wrong way all the time. Now I am confused by the different ways of drawing interface relationships in two regards (I ...
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6answers
629 views

UML aggregation: how can the "whole" exist without its "parts"?

I understand aggregation is a "whole/part" relationship, where the "parent" class is the whole and the "child" class is the part (and this is unidirectional), and that each class exist independently (...
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1answer
28 views

Approach to modeling for a new attribute to attach to exactly one of the many in a one to many relationship

Apologies for the awkward title; I wasn't quite sure how to concisely describe what I'm trying to do. My situation goes like this: We have a Product table in our database; Each Product may have 0 or ...
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3answers
3k views

Many to many relations in Domain Driven Design

I am new at domain driven design, and want to learn some about aggregates. For example I have a User and Role entities. public class User { public string Id {get; set;} public string Username ...
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11answers
10k views

Need Good OOP Design For World and Countries Problem

I am currently working on problem with a chicken or egg first situation. Basically, I am designing a solution which goes like this: World is a collection of countries; Each Country has a name, flag ...
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1answer
208 views

Can we have a ternary relationship together with a recursive one in E-R diagrams

I am designing an E-R Diagram for a simple system where there are some users and contests. A user can create a contest or invite other users to the contest who can decide to accept or not. I am ...
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2answers
104 views

How to show UML component load/discovery and realization relationships

In a UML component diagram I want to show two components (among others). One is the core component that loads contents (classes) from the other. It's much like a testframework loading unit tests/test ...
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3answers
129 views

Many-to-many assignments in user system

I have a few software architecture/design questions related to a technically quite simple problem. We already have all the functionality implemented properly, however from a design perspective it is ...
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2answers
2k views

How to handle many-to-many relationships with multiple incompatible relationship types in RESTful API?

Note this question is about when there are multiple relationship types. This is not the same as this question, where there is only a single member relationship. Say we have persons and organizations. ...
4
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3answers
184 views

ER diagram - feasibility of a requirement

I need to model the following requirement in an Entity-Relationship diagram. "Customers place orders, which contain a list of products with their quantity and prices. A shipment is made when ...
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3answers
132 views

Database relation design

When I develop apps I reach situations like this frequently but I never found a best practice to solve it. Imagine: We have chats, each chat can have many message. We have tickets, each ticket can ...
3
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1answer
145 views

Proper way to associate data to users that are stored in external database?

I have this IdentityServer which handles authentication and authorization. It saves users, roles, claims, etc in its own database. Then, I have a web app that needs to protect some resources to ...
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3answers
2k views

Factory pattern or builder pattern ? which one is suited for reading Finite Element Model data from a text file?

A follow up to another question (Making a design decision about reading model data from an input file). I wish to ask another question regarding builder or factory pattern. (I read that builder is ...
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1answer
2k views

Entities and polymorphic relationships

Lets say that I have a shelf on which I can put items that are shelfable (not sure if that is actually a word but you can understand my point). So I have the following: class Shelf { /** @var ...
4
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2answers
175 views

How to represent relations between multiple objects without obvious aggregate root

Let's say we have three types of objects: Agents Calls CallsQueues They all can be linked with each other (1to1, 1toM, MtoM) or have no links, and these links change over time. Calls wait in ...
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1answer
941 views

How to organize business logic which deals with different, but related objects

The task The piece of software I'm writing operates on the following object types: Agents Calls CallQueues These objects can be linked together, and each of them contains some additional ...
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2answers
2k views

Best diagram to show relations between several applications

I'm currently an intern at a company. For my intermediate report I Received some feedback about displaying the relations between multiple applications. So in my image all 3D rectangles are a deployed ...
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0answers
726 views

Examples for bidirectional and unidirectional relationships between objects

To better demonstrate the difficulties of reading/updating objects in a multithreaded environment, I'm looking for examples for groups of objects with a bidirectional or unidirectional relationship ...
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1answer
631 views

Imposing conditional entity relations

While working on an application, I am facing an issue. And I am not sure how to solve this. For explanation I have managed to come up with a simple example below: Consider a Grocery Store ...
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1answer
124 views

Looking for a strategy to ensure name of child node stays unique in collection

Even though I'm programming in PHP, I'm open to reviewing language-agnostic suggestions, as they might point me to valuable directions. To remove any possible confusion I feel some comments appear to ...
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3answers
232 views

How can I mark one of a 1:n relation as the "default"?

I have an "easy" question, but since I am not a very experienced programmer I would like to hear what some of you have to say. If I have for example a Db called MyDb with many tables. Two of them are ...
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1answer
221 views

What are best practices to maintain a list in the database in Rails?

I have list boxes and model relationships in the database. I'm doing the following migrations to maintain lists, rename items, and add items: def up Fund.create min: 0, max: 1_000_000 ...
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3answers
1k views

UML : is it okay to use only Association in a class diagram ?

I feel confused about the three relationships Association, Aggregation and Composition in UML. I need to finish a project soon, until it became less unclear in my head, is it okay to use only ...
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4answers
50k views

ERD: "many" vs "zero or many"/"one or many" crowfoot notation?

Background I saw this figure describing the different crowfoot notations used in ERD: I'm not able to find the difference between the "many" notation and the "zero or many. However I was able to find ...
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1answer
150 views

Can the has-a relation in OOP become ambiguous or difficult to know?

Assume I have the following code. class D { static Integer i1 = 42; } Is it true that D has an Integer? Or is it only for instance variable that we can have a has-a relation? I also wonder about ...
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4answers
241 views

Hierarchical structure that needs to enforce availability

The project I am working on has deep parent/child relationships that needs to enforce availability. Imagine we are a large Worldwide Electronic Seller (Best Buy) and selling mobile phones We have ...
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2answers
1k views

Specifying a bi-directional unique constraint on a join table in Postgres [closed]

Problem description I have a situation where I want to enforce that a relationship can only be defined once and I want to solve it on database (Postgres) level. The following situation I consider ...
4
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2answers
180 views

Designing my classes with relationships

I need to build a UI for entering values to the database. I am stuck with my class design to achieve it. I need a UI where I am able to enter the name of the system. Each system can have many options....
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0answers
64 views

How to model relationships in scenario where every product can (don't have to) be associated to only one category

This one still occupies my mind. How do you model 1:N relationships. Consider having a category and product (typical e-commerce scenario). Every product can (don't have to) be associated to only one ...
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2answers
2k views

Database design for linking parent & child relationship

Currently i have requirement saying user from an UI creates there own forms which has types textbox,choicegroup etc.. Does anyone have a any idea on how to architect the database to store all data? ...
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1answer
1k views

Laravel relationships and database schema

I am playing around with Laravel and came across something in the documentation for defining 1 to 1 relationships between tables that I would like to get feedback on. The example in the docs is ...
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2answers
1k views

Is composition and aggregation really a type of association relationship?

From Wikipedia: There are four different types of association: bi-directional, uni-directional, Aggregation (includes Composition aggregation) and Reflexive. From what I know: Composition ...
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1answer
93 views

How to associate both a collection and one item of this collection to an entity

I'm working on a project in which I have an entity, we may call Users and another entity Address. I want to define the entity User in a way that an user would have a collection of addresses (...
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4answers
376 views

Domain model associations that do not required the behaviour of the associated object. How to model?

I've been struggling with this question for a while. I'm specifically thinking within the object orientated domain model. Let's say I have two entities. A supplier and a customer. There is a ...
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3answers
353 views

Pattern to safely establish a one to one bidirectional relationship

Let suppose we have 2 classes, Pilot and Plane, being in an optional one-to-one relationship. So a Plane might have a pilot when it's flying, but when it's standing in its hangar, it has none. Similar ...
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1answer
622 views

Relation between objects

For a few weeks I’ve been thinking about relation between objects – not especially OOP’s objects. For instance in C++, we’re used to representing that by layering pointers or container of pointers in ...
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3answers
1k views

Should POCO domain classes contain collections?

The question title is not good, but I couldn't think of a way to word it better. I am used to develop using POCO classes in my projects, that is, domain objects contain absolutely no logic, only data....
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2answers
1k views

MVC: "User" model gets big and crowded. Should methods that do CRUD operations on one-to-many relationship data be in different models?

In most MVC web projects there is a User class. Many times a user has something else in a one-to-many relationship, i.e. orders. If we have a user class that has many orders, should methods that add, ...
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1answer
470 views

Need help modelling a User/Project/Task relationship

So I'm creating a very simple project/task management application in Laravel 4 and I'm not sure how these relationships would work. I have a Project, Task and User model. A User can own a Project or ...
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1answer
1k views

REST Relationships Besides Parent/Child

This would seem to be a pretty basic question, but I can't seem to find appropraite guidelines for it. What is the "restful" way of POSTing a relationship between two entities that are not necessarily ...
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2answers
18k views

Database Schema for Pricing Products (packages, promotions, qty based, limited time offer...)

I'm working on a new point of sale for a company that products for different prices depending on the product mix. All products have a base price. To explain my problem, I will use the following info:...
4
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1answer
472 views

Database Design - Optimise Relationships

I am about to embark on a redesign of an application, one where querying the database is particularly annoying. I intend to redesign the database as much as possible but the data shape cannot change ...
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1answer
147 views

Keyword Collection, ManyToOne or OneToMany relationship?

I hope this is the right place for this type of problem. An Object of my class Movie can have several keywords ( like 'fight club', 'brad', 'fincher'), and be part of different categories (like '...