Object-relational mapping (ORM) is a technique for mapping between object-oriented systems and relational databases.

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Many-to-many in OOP: Class A instantiates Class B, which instantiates Class A, which

I am mapping Field1 to Field2. The map object instantiates the field object and vice versa, creating an infinite loop. This is in PHP. class field { protected $maps; // mapCollection object. all ...
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Persistence frameworks and common sense

I have studied some persistence frameworks mainly Hibernate, DORM, TMS Aurelius and I'm wondering. In a model of type: TOrderFiscal < > ----- > Items < > -------- > TOrderItem ...
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DB Design: How to link a single column to a collection of entities

I have a db design question that I am sure has been quite extensively covered but I cannot find a good answer already. The problem is how to efficiently link a single school course to a collection ...
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Is it bad software design to mix JDBC SQL calls and use an ORM in an application? [closed]

Is it bad software design to have JDBC/raw SQL and also use an ORM? I don't mind using an ORM for boilerplate CRUD, but some queries are better in SQL (for me). I'm not arguing for or against ORMs. ...
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How to get around the Circular Reference issue with JSON and Entity

I have been experimenting with creating a website that leverages MVC with JSON for my presentation layer and Entity framework for data model/database. My Issue comes into play with serializing my ...
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How does accumulating large amounts of business logic on the model objects make building strong service contracts harder?

I heard a couple of times that putting business logic in database models is bad down the road. I just read this in blog of a Rackspace employee: The Django ORM also tended to have us accumulate large ...
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Finding next free IP in a network

I have an IP network and want to automatically find a free IP address to provision a new server. Due to frequent server additions/removals the used IPs might be quite fragmented over the whole address ...
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What kind of object relational mapping is appropriate here?

In my database I have a table that looks like this Master(ID, Name, Attr1...). Every ID will have at least 1 entry in additional tables that have additional attributes. Those tables specialize the ...
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Android: Considering an ORM tool [duplicate]

I am developing an Android app in which I have to add chat functionality. Also, I have to save the chat history. I will accomplish this task using SQlite. But, I am not sure whether should I consider ...
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Audit trails and entity relationships

I'm working on an order system and implementing an audit log. Two main concerns are: 1) While auditing a line item , you should only see audits for the line item 2) While auditing an order, you ...
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Setter Validation can affect performance?

In a scenario where you use an ORM to map your entities to the DB and you have setter validations (nullable, date lower than today validation, etc), every time the ORM gets a result, it will pass into ...
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Is inline SQL still classed as bad practice now that we have Micro ORMs?

This is a bit of an open ended question but I wanted some opinions, as I grew up in a world where inline SQL scripts were the norm, then we were all made very aware of SQL injection based issues, and ...
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When to use repository pattern

I have read recently that it is not good practice to use the repository pattern in conjunction with an ORM. From my understanding this is because the abstraction they provide over the SQL database is ...
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ORM: Design of the service layer

I'm currently writing a medium sized web-application and find myself asking this question many times. For example, let's say there are users, which have files (one-to-many). How should the UI access ...
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When using an ORM should mappings be defined in the code file?

Doctrine offers three ways to define the object mapping properties: in XML, in YAML and as inline docblock annotations in the code. The Doctrine documentation doesn't give any advice on choosing ...
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raw aql query in framework with Active Record pattern based ORM

I use yii framework that implements Active Record pattern as ORM base. It has CActiveRecord class that is a table wrapper class with attributes reflecting table columns. So each object of this class ...
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Performance related doubt in Java with Hibernate

Suppose in some ORM based project (say Hibernate) I am trying to fetch only few columns rather then the whole Object with may be more than 20 attributes. I am writing HQL like "select attr1, attr2 ...
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Getting related foreign keys from parent entities

I'm thinking about a design issue which affects my project's data base. Supposing there are three diferent tables: CLIENT ORDER PACKING_SLIP Each order has its client and different packing ...
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NHibernate and complex domain model against a legacy database

I'm trying to refactor (actually, rewrite) an application which currently uses only stored procedures to access the database (hundreds of SPs). My goal is to use Nhibernate and follow a good design as ...
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What specific features of NHibernate cause it to be recommended for legacy database systems?

So, I've been evaluating Entity Framework and NHibernate (I'm not looking for an EF vs. NH battle here, though!). One thing that I see come up very often is that NHibernate is recommended for ...
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What is a good rule-of-thumb for naming link-tables?

In the same way that a publication table might relate to a person table via subscriptions, or a company table might relate to a person table via employee, I'm wondering if there is a descriptive way ...
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543 views

Anything beneficial from ORM for a NodeJS project already plain-SQL-implemented?

Well, actually it's a assignment project and I've already implemented a simple yet functional forum with NodeJS. But now we've been required to use ORM frameworks to refactor part of your code worth ...
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What are the disadvantages of using stored procedures, SSIS, and SSRS to implement business applications? [closed]

Recently, it was suggested that many projects (where I work) should be implemented using some combination of stored procedures (on SQL Sever / T-SQL), SSIS, and SSRS. In one specific project, SSIS ...
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What is the convention regarding class names that may already exist in the ORM?

This is a generic question about class names and ORMs, but for context; I'm working on a Flask web app in Python using SQLalchemy. I'm struggling with naming a new class that will contain the ...
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Using a DAO to abstract our ORM from the rest of the application

We're using MySQL with Sequelize.js as the ORM. What we're wondering is whether a DOA layer of abstraction is worthwhile. Here are our options: To use the Sequelize models throughout the ...
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Mapping a legacy database to ORM using wrapper classes

I want to use an ORM with a legacy database, but I don't want to expose some of the underlying data types. For example, some of the columns are nullable doubles or floats and I want my domain model to ...
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What is the equivalent of Entity Framework in the world of Oracle shops? [closed]

Within the world of developers/firms specializing in building/deploying solutions built around software built/sold by Oracle (aka "Oracle houses"), what ORM middleware is considered as the "industry ...
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What is a good design for a container, assignment and items

------------- 1 * -------------- * 1 -------- | Container |--------| Assignment |-----------| User | ------------- -------------- -------- ^ ...
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Should I Use an ORM only when dealing with Data Model objects?

I am new to ORM, and we started developing a new system using NHibernate as the ORM. I think this question may refer to any ORM and any language/platform. The Team Leader has said we should use ...
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235 views

Sorting rows off an autoincrementing primary key

Is it a bad practice to rely on an auto-incrementing primary key to sort rows in a table? A coworker and I were having an argument about this subject. We need to be able to find the last-inserted row ...
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How do ORM'S manage CRUD operations in multi thread environment

Suppose I have code which retrieves an object and modifies it and submits it via any ORM from a web application. Below is the pseudo code: First request var objCust = ...
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ORM: Keep entities coherent in a cache or retrieve entities each time?

We have a tricky question in a project using Java & Hibernate, with a model containing bi-directional relationships. As it's a small project with few users, few entities, and few rows involved in ...
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Entity Framework as a type checking/verification system for database code

When I read pro and con lists of using Entity Framework (or any modern ORM really), I'm surprised that the following point doesn't arise (self quote): Using strongly-typed domain entities allows ...
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Do we achieve 100% Persistence Ignorance solution if we're not using ORM's POCO objects to model the Domain?

Persistence ignorance is ability to retrieve/persist standard objects, where standard objects are considered as classes focused on particular business problem and thus don't contain any ...
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OOP Design: relationship between entity classes

I have at first sight a simple issue but can't wrap my head around on how to solve. I have an abstract class Compound. A Compound is made up of Structures. Then there is also a Container which holds 1 ...
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Benchmarking ORM associations

I am trying to benchmark two cases of self referential many to many as described in datamapper associations. Both cases consist of an Item clss, which may require many other items. In both cases, I ...
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Where ORMs blur the lines between code and data, how do you decide what logic should be a stored procedure, and what should be coded?

Take the following pseudocode: CreateInvoiceAndCalculate(ItemsAndQuantities, DispatchAddress, User); And say CreateInvoice does the following: Create a new entry in an Invoices table belonging to ...
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Should we have a database independent SQL like query language in Django?

Note : I know we have Django ORM already that keeps things database independent and converts to the database specific SQL queries. Once things starts getting complicated it is preferred to write raw ...
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Classless tables possible with Datamapper?

I have an Item class with the following attributes: itemId,name,weight,volume,price,required_skills,required_items. Since the last two attributes are going to be multivalued, I removed them and ...
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Creating a layer of abstraction over the ORM layer

I believe that if you have your repositories use an ORM that it's already enough abstracted from the database. However, where I am working now, someone believe that we should have a layer that ...
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Database Change Auditing - Part of or Abstracted from ORM / Application Layer?

My fellow developers and I are at a crossroads in how to go about continuing our auditing of database changes. Most of our applications log changes via INSERT, UPDATE, and DELETE triggers. A few of ...
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Entity Framework with large systems - how to divide models?

I'm working with a SQL Server database with 1000+ tables, another few hundred views, and several thousand stored procedures. We are looking to start using Entity Framework for our newer projects, and ...
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Externalising SQL Queries in Java

What are the advantages and disadvantages of externalising SQL queries in Java (or similar general-purpose object-oriented programming language. Externalizing means storing all SQL in a separate ...
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How do I make code bound to an ORM testable?

In Test Driven Development, how do I make code bound to an ORM testable? I am using a Micro-ORM (PetaPoco) and I have several methods that interact with the database like: AddCustomer UpdateRecord ...
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Returning an IQueryable from an IRepository

Using the Repository pattern, is it proper to return an IQueryable of a data set (table), for generic usage? It is very handy in many cases, especially when using external libraries that leverage ...
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What is the best way to use inheritance with ORMs?

If I have a People table and those people can be at different addresses, and each address can have more than one person, thats a many-to-many relationship. So, using ORMs like Entity Framework and ...
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What are the advantages of myBatis over Hibernate? [closed]

I've done some research on my own and understand the basic concept. But some insights can only be gained through actual experience. What are the advantages of myBatis that would make it worth ...
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is it possible to auto-generate annotated POJO from a table

I wonder is it possible or is there a tool to generate annotated POJOs from a table.To make it clear,for example,Person table has fields like ,id,name,surname etc and i wanna to generate a POJO named ...
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Abstraction Layer over ORM Generated Entities

I am learning LINQ to SQL (and planning to learn Entity Framework). Initially I used a abstraction layer to convert LINQ to SQL entities into a domain objects. Later I discovered the “Inheritance ...
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Are separate business objects needed when persistent data can be stored in a usable format?

I have a system where data is stored in a persistent store and read by a server application. Some of this data is only ever seen by the server, but some of it is passed through unaltered to clients. ...