Questions tagged [relationships]

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How to handle relationships between resources in Restful API

Problem Hi, we have an API that it's pretty similar to a standard CRM. That is, we have a really big amount of resources (even our own customers can define new resources). All of these resources share ...
5 votes
3 answers
106 views

UML Composition parent association end

The Wikipedia article on the Composite Design Pattern includes the following diagram: As you see, there is an association relationship which is child 0..* – 1 parent (association). However, shouldn't ...
1 vote
2 answers
132 views

determine correct relations in ERD - Customer Orders use case

The below ERD is taken from a professional architecture reference, however I have a concern in the relation between Customer and Invoice, I believe that relation between Customer to Order , and Order ...
2 votes
3 answers
241 views

OOPS Relationship between Soccer Field and Soccer Player

I am trying to design a simple Soccer game. To keep things simple, I am having a SoccerField to represent the field and a Player class to represent an individual. A SoccerField will contain a list of ...
0 votes
1 answer
102 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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2 votes
1 answer
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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1 vote
2 answers
887 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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0 votes
1 answer
263 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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1 vote
1 answer
776 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 ...
4 votes
1 answer
3k 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 ...
6 votes
2 answers
6k 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 ...
1 vote
1 answer
977 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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4 votes
6 answers
943 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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1 vote
1 answer
31 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 ...
-1 votes
2 answers
5k 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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18 votes
11 answers
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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2 votes
1 answer
368 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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1 vote
2 answers
127 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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2 votes
3 answers
136 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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-1 votes
2 answers
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 votes
3 answers
201 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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1 vote
3 answers
152 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 votes
1 answer
172 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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4 votes
3 answers
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 ...
2 votes
1 answer
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 votes
2 answers
216 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 ...
4 votes
1 answer
1k 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 ...
4 votes
2 answers
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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0 votes
0 answers
944 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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2 votes
1 answer
846 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 ...
2 votes
1 answer
128 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 ...
3 votes
3 answers
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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0 votes
1 answer
235 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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2 votes
3 answers
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 ...
19 votes
4 answers
63k 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 ...
1 vote
1 answer
152 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 ...
3 votes
4 answers
244 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 ...
6 votes
2 answers
2k 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 ...
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4 votes
2 answers
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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0 votes
0 answers
66 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 ...
0 votes
2 answers
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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1 vote
1 answer
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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2 votes
2 answers
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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1 vote
1 answer
95 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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1 vote
4 answers
408 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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1 vote
3 answers
367 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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8 votes
1 answer
630 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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2 votes
3 answers
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....
3 votes
2 answers
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, ...
1 vote
1 answer
505 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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