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• Entity Framework, what's so bad and what's so good?

  - by AverageJoe719

  Hi all, I am curious as to what your opinions are in Entity Framework? I have read some things like the first version of it is super horrible because it doesn't handle many to many relationships (though many ORMs don't and I've never seen the issue with just making a linking table). Also is LINQ to Entities the same as Entity Framework? I think it is, but it seems like one term is used or the other. I have used Linq to SQL before, what are the advantages of it compared to that? In terms of coding preference I like to build everything from the ground up so I can fully understand it/be in control of the code I write. So I have heard that Entity Framework is harder and I know LinqToSQL handles a lot of stuff automatically, but specifically what are the differences? I appreciate your responses, Thanks =)

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• Action Controller: Exception - ID not found

  - by Danny McClelland

  Hi Everyone, I am slowly getting the hang of Rails and thanks to a few people I now have a basic grasp of the database relations and associations etc. You can see my previous questions here: http://stackoverflow.com/questions/2714621/rails-database-relationships I have setup my applications models with all of the necessary has_one and has_many :through etc. but when I go to add a kase and choose from a company from the drop down list - it doesnt seem to be assigning the company ID to the kase. You can see a video of the the application and error here: http://screenr.com/BHC You can see a full breakdown of the application and relevant source code at the Git repo here: http://github.com/dannyweb/surveycontrol If anyone could shed some light on my mistake I would be appreciate it very much! Thanks, Danny

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• Specialization hierarchy in a domain-model

  - by devoured elysium

  I'm trying to make the domain model of a management system. I have the following kinds of persons in this system: employee manager top mananger I decided to define a User, from where employee, manager and top manager will specialize from. What I don't know is what kind of specialization hierarchy I should choose from. I thought of two ways: or Which might be preferable and why? As a long time coder, every time I try to do a domain-model, I have to fight against the idea of trying to think in how I'm going to code this. From what I've understood, I should not think about those matters in the domain-model, only in object relationships. I don't have to think of code duplication or any of these kind of details here, so I can't really pick any of the options over the other. Thanks

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• insertNewObjectForEntityForName:inManagedObjectContext: returning NSNumber bug?

  - by beinstein

  I'm relatively well versed in CoreData and have been using it for several years with little or no difficulty. For the life of me, I can't figure out why insertNewObjectForEntityForName:inManagedObjectContext: is all of a sudden returning some sort of strange instance of NSNumber. GDB says the returned object is of the correct custom subclass of NSManagedObject, but when I go to print a description of the NSManagedObject itself, I get the following error: *** -[NSCFNumber objectID]: unrecognized selector sent to instance 0x3f26f50 What's even stranger, is that I'm able to set some relationships and attributes using setValue:forKey: and all is good. But when I try to set one specific relationship, I get this error: *** -[NSCFNumber entity]: unrecognized selector sent to instance 0x3f26f50 I've tried everything from clean all targets, to restarting both mac and iPhone, even editing the model so that the relationship in question is to-one instead of to-many. No matter what I do, the same problem appears. Has anyone ever seen anything like this before?

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• ORM solutions (JPA; Hibernate) vs. JDBC

  - by Grasper

  I need to be able to insert/update objects at a consistent rate of at least 8000 objects every 5 seconds in an in-memory HSQL database. I have done some comparison performance testing between Spring/Hibernate/JPA and pure JDBC. I have found a significant difference in performance using HSQL.. With Spring/Hib/JPA, I can insert 3000-4000 of my 1.5 KB objects (with a One-Many and a Many-Many relationship) in 5 seconds, while with direct JDBC calls I can insert 10,000-12,000 of those same objects. I cannot figure out why there is such a huge discrepancy. I have tweaked the Spring/Hib/JPA settings a lot trying to get close in performance without luck. I want to use Spring/Hib/JPA for future purposes, expandability, and because the foreign key relationships (one-many and many-many) are difficult to maintain by hand; but the performance requirements seem to point towards using pure JDBC. Any ideas of why there would be such a huge discrepancy?

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• How to think in data stores instead of databases?

  - by Jim

  As an example, Google App Engine uses data stores, not a database, to store data. Does anybody have any tips for using data stores instead of databases? It seems I've trained my mind to think 100% in object relationships that map directly to table structures, and now it's hard to see anything differently. I can understand some of the benefits of data stores (e.g. performance and the ability to distribute data), but some good database functionality is sacrificed (e.g. joins). Does anybody who has worked with data stores like BigTable have any good advice to working with them?

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• LINQ DataLoadOptions - Retrieval of data via Fulltext/Broken Foreign Key Relationship

  - by Alex

  I've hit a brick wall: I have an SQL Function: FUNCTION [dbo].[ContactsFTS] (@searchtext nvarchar(4000)) RETURNS TABLE AS RETURN SELECT * FROM Contacts INNER JOIN CONTAINSTABLE(Contacts, *, @searchtext) AS KEY_TBL ON Contacts.Id = KEY_TBL.[KEY] which I am calling via LINQ public IQueryable<ContactsFTSResult> SearchByFullText(String searchText) { return db.ContactsFTS(searchText); } I am projecting the ContactsFTSResult collection into a List<Contact> which is then given to my viewmodel. Here is the problem: My Contacts table (and therefore the Contact object created via LINQ to SQL) has multiple FK relationships to other information, such as Contact.BillingAddressId is an FK to an Address.Id. That information is missing after I do the fulltext search (e.g. if I try to access Contact.BillingAddress it is null). Can I add this information somehow via DataLoadOptions? I tried LoadWith<Contact>(c => c.BillingAddress) but this doesn't work, I assume because of the fact that I'm calling the function instead of doing the whole query via LINQ.

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• strategies for learning complex software packages

  - by Tom

  I am a fairly novice Java programmer and I am currently working on a project to extend a piece of software that has been developed over a few years. So it has pretty big code base and the previous developers knew it well, so extending it is not going to be easy without a thorough understanding of the structure and function. 1) I had begun by trying to tackle small parts of the system and document them with mindmap. (particularly I am trying to document the interactions with external systems) 2) I have the book "code complete", which I am working through. 3) I have pointed some tools like "tattletale" at the code to get some diagrams of dependency relationships. What other strategies should I employ, should I focus on one particular aspect?

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• free public databases with non-trivial table structures?

  - by Caffeine Coma

  I'm looking for some sample database data that I can use for testing and demonstrating a DB tool I am working on. I need a DB that has (preferably) many tables, and many foreign key relationships between the tables. Ideally the data would be in SQL dump format, or at least in something that maintains the foreign key references, and could be easily import into an RDBMS (MySQL or H2). The dataset itself doesn't have to be huge (in fact, best if it's not). I thought about using the Stackoverflow Data Dump, but it's only about 5 tables.

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• is there some PHP social crm, plugins, or frameworks?

  - by garcon1986

  Hello, What i need to do: I'm trying to realize social networking graph for companies, employees in CRM. They could have many complex relationships. A company can have its network like inverstors, partners, competitors and customers etc. I want to realize a dynamic social networking graph for it. And it has to be implemented by php. Right now, i know SugarCRM and vTigerCRM are php open source CRMs. And SugarCRM provides some social functions. And there are a lot of other CRMs, while i'm not sure if they are realized by php, such as: ACT!, Microsoft Dynamics, Oracle Siebel Social CRM, Salesforce, BatchBlue, Buzzient etc. Do you know any other php CRMs, especially php social CRMs? Thanks

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• Can Entity Framework be used for the purpose of entity/schema definition at application runtime?

  - by Kabeer

  Hello. Can 'Entity Framework' be used for the purpose of entity definition at application runtime? Ok, to make it simple, here is what I want to achieve: My application is a product. I should be able to define entities at runtime on the basis of inputs gathered from an 'authoring' user (in effect this means 'model first' approach). These entities are of course persistable. Further, after having defined the entities and their relationships, I should be able to make complex queries across them for many reasons, including reports. Is the above possible and how? So far what I have realized is that there is a dependency on Visual Studio.

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• Dealing w/ Sqlite Join results in a cursor

  - by Bill

  I have a one-many relationship in my local Sqlite db. Pretty basic stuff. When I do my left outer join I get back results that look like this: the resulting cursor has multiple rows that look like this: A1.id | A1.column1 | A1.column2 | B1.a_id_fk | B1.column1 | B1.column2 A1.id | A1.column1 | A1.column2 | B2.a_id_fk | B2.column1 | B2.column2 and so on... Is there a standard practice or method of dealing with results like this ? Clearly there is only A1, but it has many B-n relationships. I am coming close to using multiple queries instead of the "relational db way". Hopefully I am just not aware of the better way to do things. I intend to expose this query via a content provider and I would hate for all of the consumers to have to write the same aggregation logic.

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• Are there any reasons to make all fields and variables final?

  - by Roman

  In my current project I noticed that all class fields and variable inside methods are declared with final modifier whenever it's possible. Just like here: private final XMLStreamWriter _xmlStreamWriter; private final Marshaller _marshaller; private final OutputStream _documentStream; private final OutputStream _stylesStream; private final XMLStreamWriter _stylesStreamWriter; private final StyleMerger _styleMerger; public DocumentWriter(PhysicalPackage physicalPackage) throws IOException { final Package pkg = new Package(physicalPackage); final Part wordDocumentPart = pkg.createPart( "/word/document.xml", "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml", "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument"); // styles.xml final Pair<Part, String> wordStylesPart = wordDocumentPart.createRelatedPart(...); ... } Are there any reasons to do so? p.s. As I know project is not supposed to be multithreaded (at least I've heard nothing about it).

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• implmenting 1 to n mapping for ORM c++

  - by karan

  I am writing a project where i need to implment a stripped down version of an ORM solution in c++. I am struck in implmenting 1-n relationships for the same. For instance, if following are the classes: class A { } class B { std::list _a_list; } I have provided load/save menthods for loading/saving to the db. Now, if i take the case of B : Say , for the following workflow : 1 entry from _a_list is removed 1 entry from _a_list is modified 1 entry is added to _a_list Now, i need to update the db using something like "b.save()". So, what would be the best way to save the changes,i.e, identify the additions, deletions and updations to _a_list.

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• What is the best PHP framework for building a website around a heavily relational PostgreSQL databas

  - by Kenaniah

  First of all, the framework of choice needs to have excellent support for PostgreSQL. I don't care about MySQL because it doesn't have half of the features the application I will be porting requires. (And when I say excellent support, I mean that their approach to database drivers has not been solely trained in MySQL). The ideal framework: Should take full advantage of PHP 5.3 and PostgreSQL 8.4 features Should support new technologies such as OpenID and social networking Should support complex relationships between database relations Should have an intelligent validation system Should have a basic library of helpful views (such as pagination, navigation, etc) Should probably be MVC based Should have excellent documentation and an active development community Should namespace classes intelligently What I'm looking for might be more of a library of utilities, as I really don't want to be restricted by the framework in what I can and can not do. I have my own small library of core classes that take care of business logic, and I will most likely want to integrate those with the new framework as well. Thanks!

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• linq to sql using foreign keys returning iqueryable(of myEntity]

  - by Gern Blandston

  I'm trying to use Linq to SQL to return an IQueryable(of Project) when using foreign key relationships. Using the below schema, I want to be able to pass in a UserId and get all the projects created for the company the user is associated with. DB tables: Projects Projid ProjCreator FK (UserId from UserInfo table) Companyid FK (CompanyID from Companies table) UserInfo UserID PK Companyid FK Companies CompanyId PK Description I can get the iqueryable(of project) when simply getting the ProjectCreator with this: Return (From p In db.Projects _ Where p.ProjectCreator = Me.UserId) But I'm having trouble getting the syntax to get a iqueryable(of projects) when using foreign keys. Below gives me an IQueryable(of anonymous) but I can't seem to convince it to give me an IQueryable(of project) even if I try to cast it: Dim retval = (From p In db.Projects _ Join c In db.Companies On p.CompanyId Equals c.CompanyId _ Join u In db.UserInfos On u.CompanyId Equals c.CompanyId _ Where u.Login = UserId)

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• Wiki for requirements engineering

  - by Shanon

  Hi, I'm looking to to build a wiki based tool the helps/aides in the requirements engineering process. More specifically I am hoping to end up with a tool that helps inexperienced users easily create and design requirements documents on a wiki platform. I was wondering if there exist any wiki/wiki platforms that either already exist or are easily extendible or would be worth looking at that for this purpose. For instance some of the features I was hoping to add would be to add structure to a document so that information is filled out in a standardised manner. Another idea I was looking at was to somehow create relationships between different types of documents (for example- a goal diagram gets evolves/ helps in the development of the class diagram). So far I have come across FOSwiki which claims to to fully customisalble...but I'm not sure what it means and what I can really do with that. Any input on FOSwiki is also highly appreciated.

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• Data Modeling Help - Do I add another table, change existing table's usage, or something else?

  - by StackOverflowNewbie

  Assume I have the following tables and relationships: Person - Id (PK) - Name A Person can have 0 or more pets: Pet - Id (PK) - PersonId (FK) - Name A person can have 0 or more attributes (e.g. age, height, weight): PersonAttribute _ Id (PK) - PersonId (FK) - Name - Value PROBLEM: I need to represent pet attributes, too. As it turns out, these pet attributes are, in most cases, identical to the attributes of a person (e.g. a pet can have an age, height, and weight too). How do I represent pet attributes? Do I create a PetAttribute table? PetAttribute Id (PK) PetId (FK) Name Value Do I change PersonAttribute to GenericAttribute and have 2 foreign keys in it - one connecting to Person, the other connecting to Pet? GenericAttribute Id (PK) PersonId (FK) PetId (FK) Name Value NOTE: if PersonId is set, then PetId is not set. If PetId is set, PersonId is not set. Do something else?

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• MVC Entity Model not showing my table

  - by Jessica

  I have a database with multiple tables, and some basic relationships. Here is an example of the problem I am having: My Database: **Org** ID Name etc **Detail1** ID D1name **Org_Detail1** Org_ID Detail1_ID **Detail2** ID D2Name **Org_Detail2** Org_ID Detial1_ID BooleanField My problem is, the Org_detail1 table is not showing up in the entity model, but the Org_Details2 table does. I thought it may have been because the Org_Detail1 table only contains two ID fields that are both primary keys, while the Org_Details2 table contains 2 primary key ID fields as well as a boolean field. If I add a dummy field to Org_detail1 and update it, it still won't show up and wont allow me to add a new entity relating to the Org_Detail1 table. The table won't even show up in the list, but it is listed under the tables. Is there any solution to get this table to appear in my model?

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• Subsonic 3 : get only certain columns

  - by CTGA

  Hello, I use : Subsonic 3, SQL Server 2008, Json.Net Here is my problem : I have a house table with id,lot number, address, location, ownerid and an owner table with id,name, description. I'd like to get only the owner name and address of house where location is "San Francisco". How can I do this with Subsonic? My problem is I can only get a typed list or a datareader, I don't understand how to only get an array or a simple list. What is the best solution? Create a custom class ? Create a View ? Anything else ? My aim is to then serialize the data to send it back to my application, but serialization is seriously long because of the numerous relationships (My example here is simplified, there are indeed : house - owner - city - country etc.), whereas I need only 2 fields... Thank you

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• can QuickGraph support these requirements? (includes database persistence support)

  - by Greg

  Hi, Would QuickGraph be able to help me out with my requirements below? (a) want to model a graph of nodes and directional relationships between nodes - for example to model web pages/files linked under a URL, or modeling IT infrastructure and dependencies between hardware/software. The library would include methods such as * Node.GetDirectParents() //i.e. there could be more than one direct parent for a node * Node.GetRootParents() //i.e. traverse the tree to the top root parent(s) for the given node * Node.GetDirectChildren() * Node.GetAllChildren() (b) have to persist the data to a database - so it should support SQL Server and ideally SQLite as well. If it does support these requirement then I'd love to hear: any pointers to any parts of QuickGraph to dig into? what is the best concept re it's usage in terms of how to use database persistence - is it a simpler design to assume every search/method works directly on the database, or does QuickGraph support smarts to be able to work in memory and the "save" to database all changes at an appropriate point in time (e.g. like ADO.net does with DataTable etc) Thanks in advance

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• deriving activity diagram-based GUIs and CRUD them with a DB?

  - by Xin Tanaka

  i received a big book full of processes. i was thinking about the end user (they will be lawyers) and decided the best GUI would be showing activity diagrams or business processes. It reminded me Quickbooks and how non-accountants can successfully use it and understand accounting processes. i began doing research before sending my project to a bunch of programmers: is there some open source solution? can i use MS Visio libraries? which UML tool is programable? what about Eclipse and its modeling tools? etc etc the key points here are: relationships between events, artifacts, actors, etc should be stored in a database. processes or steps in a process should be easily modified by updating the database do this sounds too crazy? (should I explain a bit more why it must be programmed this way?)

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• Rails link from one model to another based on db field?

  - by Danny McClelland

  Hi Everyone, I have a company model and a person model with the following relationships: class Company < ActiveRecord::Base has_many :kases has_many :people def to_s; companyname; end end class Person < ActiveRecord::Base has_many :kases # foreign key in join table belongs_to :company end In the create action for the person, I have a select box with a list of the companies, which assigns a company_id to that person's record: <%= f.select :company_id, Company.all.collect {|m| [m.companyname, m.id]} %> In the show view for the person I can list the company name as follows: <%=h @person.company.companyname %> What I am trying to work out, is how do I make that a link to the company record? I have tried: <%= link_to @person.company.companyname %> but that just outputs the company name inside a href tag but links to the current page. Thanks, Danny

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• Data scheme question

  - by Matt

  I am designing a data model for a local city page, more like requirements for it. So 4 tables: Country, State, City, neighbourhood. Real life relationships is: Country owns multiple State which owns multiple cities which ows multiple neighbourhoods. In the data model: Do we link these with FK the same way or link each with each? Like in each table there will even be a Country ID, State ID, CityID and NeighbourhoodID so each connected with each? Other wise to reach neighbourhood from country we need to join 2 other tables in between? There are more tables I need to maintain for IP addess of cities, latitude/longitude, etc.

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• Implementing 1 to n mapping for ORM c++

  - by karan

  I am writing a project where I need to implement a stripped down version of an ORM solution in C++. I am struck in implementing 1-n relationships for the same. For instance, if the following are the classes: class A { ... } class B { ... std::list<A> _a_list; ... } I have provided load/save methods for loading/saving to the db. Now, if I take the case of B and the following workflow: 1 entry from _a_list is removed 1 entry from _a_list is modified 1 entry is added to _a_list Now, I need to update the db using something like "b.save()". So, what would be the best way to save the changes, i.e, identify the additions, deletions and updates to _a_list.

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