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• WPF MVVM Picklist Example

  - by Tim

  Hi, I am looking for a way of easily maintaining a list of Users belonging to a particular Group. I have thought about using a Picklist, where I have 2 listboxs, the first contains a list of Users the second a list of Users belonging to the Group. There will be buttons to allow the adding and removing of selected Users from the Group. As users are added they move from the left listbox to the right, as they are removed they are move from the right to the list. This is pretty common situation. Do you know of any examples of doing this in WPF using the MVVM pattern? I am having difficulty understand how the binding may work to my View Model and Business Entities. Especially persisting the data back to the database. I am using stored procedure calls to do the CRUD logic, so I need to keep a list of which Users had been removed so I can delete them. Is this the best way to perform this functionality or is there a better way. I simply want to pick from a list (the list may be large).

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• Seperating Javascript and Html, when dynamically adding html via javascript

  - by optician

  I am currently building a very dynamic table for a list application, which will basically perform basic CRUD functions via AJAX. What I would like to do is separate the visual design and javascript to the point where I can change the design side without touching the JS side. This would only work where the design stays roughly the same(i would like to use it for rapid protyping) Here is an example. <table> <tr><td>record-123</td><td>I am line 123</td><td>delete row</td></tr> <tr><td>record-124</td><td>I am line 124</td><td>delete row</td></tr> <tr><td>record-125</td><td>I am line 125</td><td>delete row</td></tr> <tr><td>add new record</td></tr> </table> Now, when I add a new record, I would like to insert a new row of html, but I would rather not put this html into the javascript file. What I am considering is creating a row like this on the page, near the table. <tr style='visble:none;' id='template-row'><td>record-id</td><td>content-area</td><td>delete row</td></tr> And when I come to add the new row, I search the page for the tags with the id=template-row , and then grab it, do a string replace on it, and then put it in the right place in the page. As long as the design doesn't shift radically, and I keep the placeholder strings the same, it means designs can be quickly modified without touching the js. Can any give any advice on a methodology like this?

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• Separating Javascript and Html, when dynamically adding html via javascript

  - by optician

  I am currently building a very dynamic table for a list application, which will basically perform basic CRUD functions via AJAX. What I would like to do is separate the visual design and javascript to the point where I can change the design side without touching the JS side. This would only work where the design stays roughly the same(i would like to use it for rapid protyping) Here is an example. <table> <tr><td>record-123</td><td>I am line 123</td><td>delete row</td></tr> <tr><td>record-124</td><td>I am line 124</td><td>delete row</td></tr> <tr><td>record-125</td><td>I am line 125</td><td>delete row</td></tr> <tr><td>add new record</td></tr> </table> Now, when I add a new record, I would like to insert a new row of html, but I would rather not put this html into the javascript file. What I am considering is creating a row like this on the page, near the table. <tr style='visble:none;' id='template-row'><td>record-id</td><td>content-area</td><td>delete row</td></tr> And when I come to add the new row, I search the page for the tags with the id=template-row , and then grab it, do a string replace on it, and then put it in the right place in the page. As long as the design doesn't shift radically, and I keep the placeholder strings the same, it means designs can be quickly modified without touching the js. Can any give any advice on a methodology like this?

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• Mapping a child collection without indexing based on database primary key or using bag

  - by Colin Bowern

  I have a existing parent-child relationship I am trying to map in Fluent Nhibernate: [RatingCollection] -- [Rating] Rating Collection has: ID (database generated ID) Code Name Rating has: ID (database generated id) Rating Collection ID Code Name I have been trying to figure out which permutation of HasMany makes sense here. What I have right now: HasMany<Rating>(x => x.Ratings) .WithTableName("Rating") .KeyColumnNames.Add("RatingCollectionId") .Component(c => { c.Map(x => x.Code); c.Map(x => x.Name); ); It works from a CRUD perspective but because it's a bag it ends up deleting the rating contents any time I try to do a simple update / insert to the Ratings property. What I want is an indexed collection but not using the database generated ID (which is in the six digit range right now). Any thoughts on how I could get a zero-based indexed collection (so I can go entity.Ratings[0].Name = "foo") which would allow me to modify the collection without deleting/reinserting it all when persisting?

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• MySQL Unique hash insertion

  - by Jesse

  So, imagine a mysql table with a few simple columns, an auto increment, and a hash (varchar, UNIQUE). Is it possible to give mysql a query that will add a column, and generate a unique hash without multiple queries? Currently, the only way I can think of to achieve this is with a while, which I worry would become more and more processor intensive the more entries were in the db. Here's some pseudo-php, obviously untested, but gets the general idea across: while(!query("INSERT INTO table (hash) VALUES (".generate_hash().");")){ //found conflict, try again. } In the above example, the hash column would be UNIQUE, and so the query would fail. The problem is, say there's 500,000 entries in the db and I'm working off of a base36 hash generator, with 4 characters. The likelyhood of a conflict would be almost 1 in 3, and I definitely can't be running 160,000 queries. In fact, any more than 5 I would consider unacceptable. So, can I do this with pure SQL? I would need to generate a base62, 6 char string (like: "j8Du7X", chars a-z, A-Z, and 0-9), and either update the last_insert_id with it, or even better, generate it during the insert. I can handle basic CRUD with MySQL, but even JOINs are a little outside of my MySQL comfort zone, so excuse my ignorance if this is cake. Any ideas? I'd prefer to use either pure MySQL or PHP & MySQL, but hell, if another language can get this done cleanly, I'd build a script and AJAX it too. Thanks!

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• Data Transfer Objects VS Domain/ActiveRecord Entities in the View in RoR

  - by leypascua

  I'm coming from a .NET background, where it is a practice to not bind domain/entity models directly to the view in not-so-basic CRUD-ish applications where the view does not directly project entity fields as-is. I'm wondering what's the practice in RoR, where the default persistence mechanism is ActiveRecord. I would assert that presentation-related info should not be leaked to the entities, not sure though if this is how real RoR heads would do it. If DTOs/model per view is the approach, how will you do it in Rails? Your thoughts? EDIT: Some examples: - A view shows a list of invoices, with the number of unique items in one column. - A list of credit card accounts, where possibly fraudulent transactions were executed. For that, the UI needs to show this row in red. For both scenarios, The lists don't show all of the fields of the entities, just a few to show in the list (like invoice #, transaction date, name of the account, the amount of the transaction) For the invoice example, The invoice entity doesn't have a field "No. of line items" mapped on it. The database has not been denormalized for perf reasons and it will be computed during query time using aggregate functions. For the credit card accounts example, surely the card transaction entity doesn't have a "Show-in-red" or "IsFraudulent" invariant. Yes it may be a business rule, but for this example, that is a presentation concern, so I would like to keep it out of my domain model.

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• ORM model and DAO in my particular case

  - by EugeneP

  I have the DB structure as follows: table STUDENT (say, id, surname, etc) table STUDENT_PROPERTIES (say, name_of_the_property:char, value_of_the_property:char, student_id:FK) table COURSE (id, name, statusofcourse_id) table STATUSOFCOURSE (id, name_of_status:char ('active','inactive','suspended' etc)) table STUDENT_COURSE (student_id,course_id,statusofcourse_id) Let's try to pick up domain objects in my database: Student and Course are main entities. Student has a list of courses he attends, also he has a list of properties, that is all for this student. Next, Course entitity. It may contain a list of students that attend it. But in fact, the whole structure looks like this: the starting point is Student, with it's PK we can look a list of his properties, then we look into the STUDENT_COURSE and extract both FK of the Course entity and also the Status of the combination, it would look like "Student named bla bla, with all his properties, attends math and the status of it is "ACTIVE". now, quotation 1) Each DAO instance is responsible for one primary domain object or entity. If a domain object has an independent lifecycle, it should have its own DAO. 2) The DAO is responsible for creations, reads (by primary key), updates, and deletions -- that is, CRUD -- on the domain object. Now, first question is What are entities in my case? Student, Course, Student_Course, Status = all except for StudentProperties? Do I have to create a separate DAO for every object?

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• DDD and Client/Server apps

  - by Christophe Herreman

  I was wondering if any of you had successfully implemented DDD in a Client/Server app and would like to share some experiences. We are currently working on a smart client in Flex and a backend in Java. On the server we have a service layer exposed to the client that offers CRUD operations amongst some other service methods. I understand that in DDD these services should be repositories and services should be used to handle use cases that do not fit inside a repository. Right now, we mimic these services on the client behind an interface and inject implementations (Webservices, RMI, etc) via an IoC container. So some questions arise: should the server expose repositories to the client or do we need to have some sort of a facade (that is able to handle security for instance) should the client implement repositories (and DDD in general?) knowing that in the client, most of the logic is view related and real business logic lives on the server. All communication with the server happens asynchronously and we have a single threaded programming model on the client. how about mapping client to server objects and vice versa? We tried DTO's but reverted back to exposing the state of our objects and mapping directly to them. I know this is considered bad practice, but it saves us an incredible amount of time) In general I think a new generation of applications is coming with the growth of Flex, Silverlight, JavaFX and I'm curious how DDD fits into this.

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• Fork or copy a users browser session in IE

  - by jmoeller

  Is it possible to fork a users session (or do something similar) in a Internet Explorer plugin? I want to process the page the user is on when they click a button in the toolbar. To avoid interrupting the users browsing, I'd like to "copy" everything so I can parse and process the page in the background. The processing can involve things such as loading the content of the result links on a Google search, if that's where the button was clicked. So - what I basically want is to imitate "Ctrl+N" but hide the window from the user, so they won't be interrupted. As you can see, if you fill out and submit the form on http://www.snee.com/xml/crud/posttest.html and press "Ctrl+N", everything posted will still appear in the new window, but it won't post the data twice. I was thinking of somehow copying the IWebBrowser2, but: I'm not sure if that's possible (I haven't been able to find any information on MSDN) I don't know if it copies the sessions as well. Creating a new instance of the IWebBrowser2 and simply navigating to the current URL isn't a valid solution as POST-variables of course doesn't get carried over.

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• Should the entity framework + self tracking entities be saving me time

  - by sipwiz

  I've been using the entity framework in combination with the self tracking entity code generation templates for my latest silverlight to WCF application. It's the first time I've used the entity framework in a real project and my hope was that I would save myself a lot of time and effort by being able to automatically update the whole data access layer of my project when my database schema changed. Happily I've found that to be the case, updating my database schema by adding a new table, changing column names, adding new columns etc. etc. can be propagated to my business object classes by using the update from database option on the entity framework model. Where I'm hurting is the CRUD operations within my WCF service in response to actions on my Silverlight client. I use the same self tracking entity framework business objects in my Silverlight app but I find I'm continually having to fight against problems such as foreign key associations not being handled correctly when updating an object or the change tracker getting confused about the state of an object at the Silverlight end and the data access operation within the WCF layer throwing a wobbly. It's got to a point where I have now spent more time dealing with this quirks than I have on my previous project where I used Linq-to-SQL as the starting point for rolling my own business objects. Is it just me being hopeless or is the self tracking entities approach something that should be avoided until it's more mature?

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• Why do people say that Ruby is slow?

  - by stephen murdoch

  I like Ruby on Rails and I use it for all my web development projects. A few years ago there was a lot of talk about Rails being a memory hog and about how it didn't scale very well but these suggestions were put to bed by Gregg Pollack here. Lately though, I've been hearing people saying that Ruby itself is slow. Why is Ruby considered slow? I do not find Ruby to be slow but then again, I'm just using it to make simple CRUD apps and company blogs. What sort of projects would I need to be doing before I find Ruby becoming slow? Or is this slowness just something that affects all programming languages? What are your options as a Ruby programmer if you want to deal with this "slowness"? Which version of Ruby would best suit an application like Stack Overflow where speed is critical and traffic is intense? The questions are subjective, and I realise that architectural setup (EC2 vs standalone servers etc) makes a big difference but I'd like to hear what people think about Ruby being slow. Finally, I can't find much news on Ruby 2.0 - I take it we're a good few years away from that then?

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• Synchronizing a collection of wrapped objects with a collection of unwrapped objects

  - by Kenneth Cochran

  I have two classes: Employee and EmployeeGridViewAdapter. Employee is composed of several complex types. EmployeeGridViewAdapter wraps a single Employee and exposes its members as a flattened set of system types so a DataGridView can handle displaying, editing, etc. I'm using VS's builtin support for turning a POCO into a data source, which I then attach to a BindingSource object. When I attach the DataGridView to the BindingSource it creates the expected columns and at runtime I can perform the expected CRUD operations. All is good so far. The problem is the collection of adapters and the collection of employees aren't being synchronized. So all the employees I create an runtime never get persisted. Here's a snippet of the code that generates the collection of EmployeeGridViewAdapter's: var employeeCollection = new List<EmployeeGridViewAdapter>(); foreach (var employee in this.employees) { employeeCollection.Add(new EmployeeGridViewAdapter(employee)); } this.view.Employees = employeeCollection; Pretty straight forward but I can't figure out how to synchronize changes back to the original collection. I imagine edits are already handled because both collections reference the same objects but creating new employees and deleting employees aren't happening so I can't be sure.

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• using Autofac in a multi-layered architecture

  - by Kamyar

  I'm fairly new to the DI/IoC concept and would like to use Autofac in a 3-layered ASP.NET Webforms application. UI layer: An ASP.NET webforms website. BLL: Business logic layer which calls the repositories on DAL. DAL: .EDMX file (Entity Model) and ObjectContext with Repository classes which abstract the CRUD operations for each entity. Entities: The POCO Entities. Persistence Ignorant. Generated by Microsoft's ADO.Net POCO Entity Generator. I have asked a more general question here. Basically, I'd like to create an obejctcontext per HttpContext in my DAL. But i don't want to add a reference to DAL in UI or access to HttpContext in DAL directly. I guess this is where IoC tools come to play. The answer to my previous question is a very good example of using Windsor Castle. I'd like to use Autofac as my IoC tool and Don't know how to achieve this. (How to access DAL in application_start to register the component while I don't want to reference it in my UI, what are the proper references to be able to use DAL component in BLL with Autofac, Should I register BLL as a component with Autofac too) Sorry folks for not providing an explicit question and requesting a kind of working example, But I'm very unfamiliar to the whole IoC concept and I don't think I can achieve it to use in my current time-limited project.

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• jqGrid : "All in One" approach width jqGridEdit Class > how to set a composite primary key ?

  - by Qualliarys

  Hello, How to set a composite primary key for a "All in One" approach (grid defined in JS file, and data using jqGridEdit Class in php file) ? Please, for me a composite primary key of a table T, is a elementary primary key that is defined with some fields belong to this table T ! Here is my test, but i get no data and cannot use the CRUD operations : In my JS file i have this lines code: ... colModel":[ {"name":"index","index":"index","label":"index"}, // <= THAT'S JUST THE INDEX OF MY TABLE {"name":"user","index":"user","label":"user","key":true}, // <= A PART OF MY COMPOSITE PRIMARY KEY {"name":"pwd","index":"pwd","label":"pwd","key":true}, // <= A PART OF MY COMPOSITE PRIMARY KEY {"name":"state","index":"state","label":"state","key":true}, // <= A PART OF MY COMPOSITE PRIMARY KEY ... <= AND SO ON "url":"mygrid_crud.php", "datatype":"json", "jsonReader":{repeatitems:false}, "editurl": "mygrid_crud.php", "prmNames":{"id":"index"} // <= WHAT I NEED TO WRITE HERE ??? ... In my php file (mygrid_crud.php) : ... $grid = new jqGridEdit($conn); $query = "SELECT * FROM mytable WHERE user='$user' and pwd='$pwd' and state='$state'..."; // <= SELECT * it's ok or i need to specify all fields i need ? $grid->SelectCommand = $query; $grid->dataType = "json"; $grid->table = 'mytable'; $grid->setPrimaryKeyId('index'); // <= WHAT I NEED TO WRITE HERE ??? ... $grid->editGrid(); Please, say me what is wrong, and how to do to set a composite primary key in this approach !? Thank you so much for tour responses.

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• What is a good programming language/environment for Linux database applications?

  - by Dkellygb

  I could use some advice on my move from the Windows world to Linux. For my business, I have used VB6 and Microsoft Access with both Access databases and SQL server in the past. The easy to use forms, report writers and programming language were perfect for CRUD apps and analysis for our small hotel/restaurant business. After using Linux at home for some time I would like to convert our small business. Our server is already a Linux box using Samba. I am happy with the OpenOffice.org applications instead of Microsoft Office. The only thing which is holding me back is a desktop database application where I can develop the forms and reports we require. Base does not seem to be up to the job yet from my experience. I would like something like VB.Net with visual studio (express) but I would like to avoid Mono – I just don’t see the point of it. (You can correct me if I’m wrong.) But a good collection of forms, controls and a good report writer would be ideal. I have looked at web based stuff like Ruby on Rails, but I think a webserver for our 5 pc network is overkill. I don’t mind running a proper database on our Ubuntu 9.10 server. I may have exposed a few prejudices above but my mind is open. Any thoughts?

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• Easiest RPC client method in PHP

  - by T.K.

  I've been asked to help a friend's company to bring up a web application. I have very limited time and I reluctantly accepted the request, at one condition. As most of the logic goes on in the back-end, I suggested that I would finish the complete back-end only, allowing a front-end developer to simply interface with my backend. I plan to do the back-end in Java EE or Python (with Pylons). It does not really matter at this point. I plan to have my back-end completely ready and unit-tested, so that my input will hardly be needed after my work is done. I know they have a PHP programmer, but as far as I could tell he is a real rookie. I want him to basically interface with my backend's services in the easiest possible way, with no way of him "stuffing" it up. It's basically a CRUD-only application. I could implement the backend as accessible through a webservice such as XML-RPC or SOAP. Even a RESTful API could be possible. However, my main objective is to make something that complete "noob" PHP programmer can easily interface with without getting confused. Preferably I do not even want to talk to him because I generally have an extremely busy schedule, and doing "support calls" is not something I am willing to do. Which approach should I choose? I would welcome any suggestions and inputs!

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• WPF View/ViewModels using Generics- how?

  - by Investor5555

  New to WPF, so please bear with me... Suppose I have 2 tables in SQL Thing OtherThing Both have the exact same fields: ID (int) Name (string) Description (string) IsActive (bit/bool) DateModified (DateTime) So, I want to create one Model (not two) and do something like this: BaseModel<T>() { public int ID {get;set;} ... } etc. (of course, using the INotifyPropertyChanged, just trying to keep the code simple). I want to be able to create a BaseView and BaseViewModel that would work with whatever model conforms to the Thing/OtherThing. I am really at a loss as to what to do here to make this generic, so I don't have to have a ThingView/ThingViewModel and a OtherThingView/OtherThingViewModel... It seems that this should be simple, but I cannot seem to figure it out. Does anyone have a code example where they could interchange various items from a dropdown list using one view, one ViewModel, and one base datamodel (and switching out the type from a dropdown)? For example, a combobox has 3 identical table structures for Thing OtherThing SomeThing and on selection changed, I want to pull the data from whatever table was selected, to be able to do standard CRUD operations on any of these 3 tables, without having to create concrete classes for each view/viewmodel.

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• PHP: MVC and Model

  - by Pirkka

  Hello I`ve been wondering this one thing about creating models. If I make for example Page model. Is it the both: It can retrieve one row from the table or all the rows. Somehow Im mixing the objects and the database. I have thought it like this: I would have to make a Page-class that would represent one row in the table. It also would have all the basic CRUD-methods. Then I would have to do a Pages-class (somekind of collection) that would retrieve rows from the table and instantiate a Page object from each row. Is this kind of weird? If someone could explain to me the idea of model throughout.. Im again confused. Maybe Im thinking the whole OOP too difficult.. And by the way this forum is great. Hopefully people will just understand my problems. Heh. I was a long time procedural style programmer and now in 3 months I have dived into OOP and MVC and PHP frameworks and I just get more excited day by day when I explore this stuff!

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• How to handle authenticated user access to resources in document oriented system?

  - by Jeremy Raymond

  I'm developing a document oriented application and need to manage user access to the documents. I have a module that handles user authentication, and another module that handles document CRUD operations on the data store. Once a user is authenticated I need to enforce what operations the user can and cannot perform to documents based upon the user's permissions. The best option I could think of to integrate these two pieces together would be to create another module that duplicates the data API but that also takes the authenticated user as a parameter. The module would delegate the authorization check to the auth module and delegate the document operation to the data access module. Something like: -module(auth_data_access). % User is authenticated (logged into the system) % save_doc validates if user is allowed to save the given document and if so % saves it returning ok, else returns {error, permission_denied} save_doc(Doc, User) -> case auth:save_allowed(Doc, User) of ok -> data_access:save_doc(Doc); denied -> {error, permission_denied} end end. Is there a better way I can handle this?

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• "Session is Closed!" - NHibernate

  - by Alexis Abril

  This is in a web application environment: An initial request is able to successfully complete, however any additional requests return a "Session is Closed" response from the NHibernate framework. I'm using a HttpModule approach with the following code: public class MyHttpModule : IHttpModule { public void Init(HttpApplication context) { context.EndRequest += ApplicationEndRequest; context.BeginRequest += ApplicationBeginRequest; } public void ApplicationBeginRequest(object sender, EventArgs e) { CurrentSessionContext.Bind(SessionFactory.Instance.OpenSession()); } public void ApplicationEndRequest(object sender, EventArgs e) { ISession currentSession = CurrentSessionContext.Unbind( SessionFactory.Instance); currentSession.Dispose(); } public void Dispose() { } } SessionFactory.Instance is my singleton implementation, using FluentNHibernate to return an ISessionFactory object. In my repository class, I attempt to use the following syntax: public class MyObjectRepository : IMyObjectRepository { public MyObject GetByID(int id) { using (ISession session = SessionFactory.Instance.GetCurrentSession()) return session.Get<MyObject>(id); } } This allows code in the application to be called as such: IMyObjectRepository repo = new MyObjectRepository(); MyObject obj = repo.GetByID(1); I have a suspicion my repository code is to blame, but I'm not 100% sure on the actual implementation I should be using. I found a similar issue on SO here. I too am using WebSessionContext in my implementation, however, no solution was provided other than writing a custom SessionManager. For simple CRUD operations, is a custom session provider required apart from the built in tools(ie WebSessionContext)?

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• Doctrine Default Primary Key Problem (Again)

  - by 01010011

  Hi, Should I change all of my uniquely-named MySQL database primary keys to 'id' to avoid getting errors related to Doctrine's default primary key set in the plugin 'doctrine_pi.php'? To further elaborate, I am getting the following reoccurring error, this time after trying to login to my login page: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'u.book_id' in 'field list'' in... I suspect the problem resides at a MySQL table used for my login, of which has a primary key called id Marc B originally solved an identical problem for me in this post http://stackoverflow.com/questions/2702229/doctrine-codeigniter-mysql-crud-errors when I had the same problem with a different table within the same database. Following his suggestion, I changed the default primary key located at system/application/plugins/doctrine_pi.php from 'id' to 'book_id': <?php // system/application/plugins/doctrine_pi.php ... // set the default primary key to be named 'id', integer, 4 bytes Doctrine_Manager::getInstance()->setAttribute( Doctrine::ATTR_DEFAULT_IDENTIFIER_OPTIONS, array('name' => 'book_id', 'type' => 'integer', 'length' => 4)); and that solved my previous problem. However, my login page stopped working. So what is the safe thing to do? Change all of my primary keys to 'id' (will that solve the problem without causing some other problem I am not aware of). Or should I add some lines of code in doctrine_pi.php?

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• jquery ajax post and response evaluation

  - by Rami

  Hello people, i am relatively new to javascript and jquery in particular, so please bear with me, i am trying to loop through multiple s and then serialize() the data with jquery and post it using ajax to my page, this's happening alright, and the data is posted, and my php script echos 1 and everything is taken care off, but for some strange reason, the following code is not working, specially the "success" variable, it's not increasing at all! would you please help me? $('.submitB').click(function(){ var success = 0; var times = 0; var alertText; $('.input').each(function(){ times++; var serializedForms = $(this).serialize(); $.post('<?=$this->config->site_url()?>crud/additem/forms', serializedForms ,function(data){ if (data) { success++; } }); }); if (times) { alertText = "?? ????? " + success + " ???? ?? ??? " + times + " ?????."; alert(alertText); } }) the Arabic text just says "success + Entries from + times + were entered successfully".. thank you in advance.

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• EJB and JPA and @OneToMany - Transaction too long?

  - by marioErr

  Hello. I'm using EJB and JPA, and when I try to access PhoneNumber objects in phoneNumbers attribute of Contact contact, it sometimes take several minutes for it to actually return data. It just returns no phoneNumbers, not even null, and then, after some time, when i call it again, it magically appears. This is how I access data: for (Contact c : contactFacade.findAll()) { System.out.print(c.getName()+" "+c.getSurname()+" : "); for (PhoneNumber pn : c.getPhoneNumbers()) { System.out.print(pn.getNumber()+" ("+pn.getDescription()+"); "); } } I'm using facade session ejb generated by netbeans (basic CRUD methods). It always prints correct name and surname, phonenumbers and description are only printed after some time (it varies) from creating it via facade. I'm guessing it has something to do with transactions. How to solve this? These are my JPA entities: contact @Entity public class Contact implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String name; private String surname; @OneToMany(cascade = CascadeType.REMOVE, mappedBy = "contact") private Collection<PhoneNumber> phoneNumbers = new ArrayList<PhoneNumber>(); phonenumber @Entity public class PhoneNumber implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String number; private String description; @ManyToOne() @JoinColumn(name="CONTACT_ID") private Contact contact;

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• Domain model for an optional many-many relationship

  - by Greg

  Let's say I'm modeling phone numbers. I have one entity for PhoneNumber, and one for Person. There's a link table that expresses the link (if any) between the PhoneNumber and Person. The link table also has a field for DisplayOrder. When accessing my domain model, I have several Use Cases for viewing a Person. I can look at them without any PhoneNumber information. I can look at them for a specific PhoneNumber. I can look at them and all of their current (or past) PhoneNumbers. I'm trying to model Person, not only for the standard CRUD operations, but for the (un)assignment of PhoneNumbers to a Person. I'm having trouble expressing the relationship between the two, especially with respects to the DisplayOrder property. I can think of several solutions but I'm not sure of which (if any) would be best. A PhoneNumberPerson class that has a Person and PhoneNumber property (most closely resembles database design) A PhoneCarryingPerson class that inherits from Person and has a PhoneNumber property. A PhoneNumber and/or PhoneNumbers property on Person (and vis-a-versa, a Person property on PhoneNumber) What would be a good way to model this that makes sense from a domain model perspective? How do I avoid misplaced properties (DisplayOrder on Person) or conditionally populated properties?

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• Sorting out POCO, Repository Pattern, Unit of Work, and ORM

  - by CoffeeAddict

  I'm reading a crapload on all these subjects: POCO Repository Pattern Unit of work Using an ORM mapper ok I see the basic definitions of each in books, etc. but I can't visualize this all together. Meaning an example structure (DL, BL, PL). So what, you have your DL objects that contain your CRUD methods, then your BL objects which are "mapped" using an ORM back to your DL objects? What about DTOs...they're your DL objects right? I'm confused. Can anyone really explain all this together or send me example code? I'm just trying to put this together. I am determining whether to go LINQ to SQL or EF 4 (not sure about NHibrernate yet). Just not getting the concepts as in physical layers and code layers here and what each type of object contains (just properties for DTOs, and CRUDs for your core DL classes that match the table fields???). I just need some guidance here. I'm reading Fowler's books and starting to read Evans but just not all there yet.

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