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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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  • Some good websites to learn about JavaScript and programming architecture?

    - by Jack Roscoe
    I'm not sure if 'architecture' is the correct term, but I've been looking for some articles online which talk about programming design and more about how best to use languages such as JavaScript in a code design sense rather than the actual syntax itself. I have found many websites but a lot seem to be very out dated, and I'm not sure what developments have taken place with JavaScript over the years so do not know how old is too old. If anybody could suggest some great websites, or maybe specific articles you think would be useful, that would be highly appreciated. I am a beginner programmer currently using JavaScript with XML and of course HTML & CSS, and I'm currently trying to get further into and learn more about web development.

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  • Of Models / Entities and N-tier applications

    - by Jonn
    I've only discovered a month ago the folly of directly accessing entities / models from the data access layer of an n-tier app. After reading about ViewModels while studying ASP.NET MVC, I've come to understand that to make a truly extensible application the model that the UI layer interacts with must be different from the one that the Data Access layer has access to. But what about the Business layer? Should I have a different set of models for my business layer as well? For true separation of concern, should I have a specific set of models that are relevant only to my business layer so as not to mess around with any entities (possibly generated by for example, the entity framework, or EJB) in the DAL or would that be overkill?

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  • Where to handle fatal exceptions

    - by Stephen Swensen
    I am considering a design where all fatal exceptions will be handled using a custom UncaughtExceptionHandler in a Swing application. This will include unanticipated RuntimeExceptions but also custom exceptions which are thrown when critical resources are unavailable or otherwise fail (e.g. a settings file not found, or a server communication error). The UncaughtExceptionHandler will do different things depending on the specific custom exception (and one thing for all the unanticipated), but in all cases the application will show the user an error message and exit. The alternative would be to keep the UncaughtExceptionHandler for all unanticipated exceptions, but handle all other fatal scenarios close to their origin. Is the design I'm considering sound, or should I use the alternative?

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  • Database Abstraction & Factory Methods

    - by pws5068
    I'm interested in learning more about design practices in PHP for Database Abstraction & Factory methods. For background, my site is a common-interest social networking community currently in beta mode. Currently, I've started moving my old code for object retrieval to factory methods. However, I do feel like I'm limiting myself by keeping a lot of SQL table names and structure separated in each function/method. Questions: Is there a reason to use PEAR (or similar) if I dont anticipate switching databases? Can PEAR interface with the MySqli prepared statements I currently use? Will it help me separate table names from each method? (If no, what other design patterns might I want to research?) Will it slow down my site once I have a significantly large member base?

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  • Zend without Database

    - by dbemerlin
    Hi, i googled for an hour now but maybe my Google-Fu is just too weak, i couldn't find a solution. I want to create an application that queries a service via JSON requests (all data and backend/business logic is stored in the service). With plain PHP it's simple enough since i just make a curl request, json_decode the result and get what i need. This already works quite well. A request might look like this: Call http://service-host/userlist with body: {"logintoken": "123456-1234-5678-901234"} Get Result: { "status": "Ok", "userlist":[ {"name": "foo", "id": 1}, {"name": "bar", "id": 2} ] } Now we want to get that into the Zend Framework since it's a hobby project and we want to learn about Zend. The problem is that all information i could find use a Database. Is there even a way to create a Zend Project that does not use a Database? And how can i write a model that represents the actions instead of objects and object-relations?

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  • How do you store sets in Cassandra?

    - by Ben W
    I'd like to convert this JSON to a data model in Cassandra, where each of the arrays is a set with no duplicates: var data = { "data1": { "100": [1, 2, 3], "200": [3, 4] }, "data2": { "k1", [1], "k2", [4, 5] } } I'd like to query like this: data["data1"]["100"] to retrieve the sets. Anyone know how you might model this in Cassandra? (The only thing I came up with was columns whose name was a set value and the value of the column was an empty string, but that felt wrong.) It's not OK to serialize the sets as JSON or some other string, which would make this much easier. Also, I should note that it's OK to split data1 and data2 into separate ColumnFamilies, it's not necessary that they're keys in the same one.

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  • MCV/MVP Patterns and Applications that interface with Hardware (DAQ/PLC/etc)

    - by Ryan
    I've been reading a lot about the MCV and MVP patterns for use with UI and it seems like a really nice powerful way to handle user interfaces. I am - however - having a difficult time deciding how this could integrate into a system where data in the model is created from a Data Acquisition System or Serial/Ethernet devices. There is also the added step that 70% of application interaction is performed by a PLC instead of a live user. It seems that for apps that just read/write & manipulate information from a database this works great, but how does does hardware and automation fit into these patterns? Is it as simple as another controller (for lack of a better term) that interacts with hardware that manipulates data and writes to a model? Maybe I am over thinking this or thinking too simply, so any advice would be great. I'm not quite sure where I'm going with this, so if something doesn't make sense or I was too vague leave me a comment. Thanks!

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  • Controlling CodeModel's code output formatting: putting lines between namespace declarations

    - by devoured elysium
    I'm making some experiments with Visual Studio's CodeModel. I tried creating a file with two namespaces in there through VS's Code Model: CodeModel codeModel = projItem.ContainingProject.CodeModel; codeModel.AddNamespace("Namespaces.FirstNamespace", "namespacestest.cs"); codeModel.AddNamespace("Namespaces.SecondNamespace", "namespacestest.cs"); the output of such code is: //file namespacestest.cs namespace Namespaces.FirstNamespace { } namespace Namespaces.SecondNamespace { } Which is almost what I'm looking for. The only catch here is that I'd like to control the spacing: having at least one line between the first and the second namespace. Does by chance anyone know of a way of achieving this? This is what I want: //file namespacestest.cs namespace Namespaces.FirstNamespace { } namespace Namespaces.SecondNamespace { } Thanks

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  • Has anybody used the WB B-tree library?

    - by Chris B
    I stumbled across the WB on-disk B-tree library: http://people.csail.mit.edu/jaffer/WB It seems like it could be useful for my purposes (swapping data to disk during very large statistical calculations that do not fit in memory), but I was wondering how stable it is. Reading the manual, it seems worringly 'researchy' - there are sections labelled [NOT IMPLEMENTED] etc. But maybe the manual is just out-of-date. So, is this library useable? Am I better off looking at Tokyo Cabinet, MemcacheDB, etc.? By the way I am working in Java.

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  • PHP Multiple User Login Form - Navigation to Different Pages Based on Login Credentials

    - by Zulu Irminger
    I am trying to create a login page that will send the user to a different index.php page based on their login credentials. For example, should a user with the "IT Technician" role log in, they will be sent to "index.php", and if a user with the "Student" role log in, they will be sent to the "student/index.php" page. I can't see what's wrong with my code, but it's not working... I'm getting the "wrong login credentials" message every time I press the login button. My code for the user login page is here: <?php session_start(); if (isset($_SESSION["manager"])) { header("location: http://www.zuluirminger.com/SchoolAdmin/index.php"); exit(); } ?> <?php if (isset($_POST["username"]) && isset($_POST["password"]) && isset($_POST["role"])) { $manager = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["username"]); $password = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["password"]); $role = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["role"]); include "adminscripts/connect_to_mysql.php"; $sql = mysql_query("SELECT id FROM Users WHERE username='$manager' AND password='$password' AND role='$role' LIMIT 1"); $existCount = mysql_num_rows($sql); if (($existCount == 1) && ($role == 'IT Technician')) { while ($row = mysql_fetch_array($sql)) { $id = $row["id"]; } $_SESSION["id"] = $id; $_SESSION["manager"] = $manager; $_SESSION["password"] = $password; $_SESSION["role"] = $role; header("location: http://www.zuluirminger.com/SchoolAdmin/index.php"); } else { echo 'Your login details were incorrect. Please try again <a href="http://www.zuluirminger.com/SchoolAdmin/index.php">here</a>'; exit(); } } ?> <?php if (isset($_POST["username"]) && isset($_POST["password"]) && isset($_POST["role"])) { $manager = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["username"]); $password = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["password"]); $role = preg_replace('#[^A-Za-z0-9]#i', '', $_POST["role"]); include "adminscripts/connect_to_mysql.php"; $sql = mysql_query("SELECT id FROM Users WHERE username='$manager' AND password='$password' AND role='$role' LIMIT 1"); $existCount = mysql_num_rows($sql); if (($existCount == 1) && ($role == 'Student')) { while ($row = mysql_fetch_array($sql)) { $id = $row["id"]; } $_SESSION["id"] = $id; $_SESSION["manager"] = $manager; $_SESSION["password"] = $password; $_SESSION["role"] = $role; header("location: http://www.zuluirminger.com/SchoolAdmin/student/index.php"); } else { echo 'Your login details were incorrect. Please try again <a href="http://www.zuluirminger.com/SchoolAdmin/index.php">here</a>'; exit(); } } ?> And the form that the data is pulled from is shown here: <form id="LoginForm" name="LoginForm" method="post" action="http://www.zuluirminger.com/SchoolAdmin/user_login.php"> User Name:<br /> <input type="text" name="username" id="username" size="50" /><br /> <br /> Password:<br /> <input type="password" name="password" id="password" size="50" /><br /> <br /> Log in as: <select name="role" id="role"> <option value="">...</option> <option value="Head">Head</option> <option value="Deputy Head">Deputy Head</option> <option value="IT Technician">IT Technician</option> <option value="Pastoral Care">Pastoral Care</option> <option value="Bursar">Bursar</option> <option value="Secretary">Secretary</option> <option value="Housemaster">Housemaster</option> <option value="Teacher">Teacher</option> <option value="Tutor">Tutor</option> <option value="Sanatorium Staff">Sanatorium Staff</option> <option value="Kitchen Staff">Kitchen Staff</option> <option value="Parent">Parent</option> <option value="Student">Student</option> </select><br /> <br /> <input type="submit" name = "button" id="button" value="Log In" onclick="javascript:return validateLoginForm();" /> </h3> </form> Once logged in (and should the correct page be loaded, the validation code I have at the top of the script looks like this: <?php session_start(); if (!isset($_SESSION["manager"])) { header("location: http://www.zuluirminger.com/SchoolAdmin/user_login.php"); exit(); } $managerID = preg_replace('#[^0-9]#i', '', $_SESSION["id"]); $manager = preg_replace('#[^A-Za-z0-9]#i', '', $_SESSION["manager"]); $password = preg_replace('#[^A-Za-z0-9]#i', '', $_SESSION["password"]); $role = preg_replace('#[^A-Za-z0-9]#i', '', $_SESSION["role"]); include "adminscripts/connect_to_mysql.php"; $sql = mysql_query("SELECT id FROM Users WHERE username='$manager' AND password='$password' AND role='$role' LIMIT 1"); $existCount = mysql_num_rows($sql); if ($existCount == 0) { header("location: http://www.zuluirminger.com/SchoolAdmin/index.php"); exit(); } ?> Just so you're aware, the database table has the following fields: id, username, password and role. Any help would be greatly appreciated! Many thanks, Zulu

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  • How to properly reserve identity values for usage in a database?

    - by esac
    We have some code in which we need to maintain our own identity (PK) column in SQL. We have a table in which we bulk insert data, but we add data to related tables before the bulk insert is done, thus we can not use an IDENTITY column and find out the value up front. The current code is selecting the MAX value of the field and incrementing it by 1. Although there is a highly unlikely chance that two instances of our application will be running at the same time, it is still not thread-safe (not to mention that it goes to the database everytime). I am using the ADO.net entity model. How would I go about 'reserving' a range of id's to use, and when that range runs out, grab a new block to use, and guarantee that the same range will not be used.

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  • What question(s) does an object's behavior answer?

    - by Corwin
    Reading a book I have found the following statement: (Object) Behaviors answer either of two questions: What does this object do (for me)? or What can I do to this object? In the case of an orange, it doesn’t do a whole lot, but we can do things to it. One behavior is that it can be eaten. In my understanding of object behaviour the statement above is correct regarding the first question and is incorrect in case of the second. However, I often see classes with methods like Orange::eat(), and this makes me uncertain about my design skills. So I would like to ask is it a design mistake to give oranges a behaviour eat? (oranges and eat are used just for example)

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  • Architecture of a single-page JavaScript web application?

    - by fig-gnuton
    How should a complex single-page JS web application be structured on the client-side? Specifically I'm curious about how to cleanly structure the application in terms of its model objects, UI components, any controllers, and objects handling server persistence. MVC seemed like a fit at first. But with UI components nested at various depths (each with their own way of acting on/reacting to model data, and each generating events which they themselves may or may not handle directly), it doesn't seem like MVC can be cleanly applied. (But please correct me if that's not the case.) -- (This question resulted in two suggestions of using ajax, which is obviously needed for anything other than the most trivial one-page app.)

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  • Django complex queries

    - by Josh K
    I need to craft a filter for an object that checks date ranges. Right now I'm performing a very inefficient loop which checks all the objects. I would like to simplify this to a database call. The logic is you have a start and an end date objects. I need to check if the start OR the end is within the range of an appointment. if (start >= appointment.start && start < appointment.end) || (end > appointment.start && end <= appointment.end) I could do this in SQL, but I'm not as familiar with the Django model structure for more complex queries.

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  • Can I add columns in a QListView in Qt ??

    - by Vic.
    Can I add columns in a QListView object?? here's something I found here: model->setHeaderData( 0, Qt::Horizontal, "numéro" ); model->setHeaderData( 1, Qt::Horizontal, "prénom" ); model->setHeaderData( 2, Qt::Horizontal, "nom" ); //... model->setData( model->index( line, 0 ), contact->num(), Qt::DisplayRole ); model->setData( model->index( line, 1 ), contact->prenom(), Qt::DisplayRole ); model->setData( model->index( line, 2 ), contact->nom(), Qt::DisplayRole ); Since I'm using Qt Creator 2.0.1, I figured my model would be: ui->ObjectName->model() The application builds successfully but I get a: "The program has unexpectedly finished." at runtime. Any Ideas ? Thanks.

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  • Extending ClaimsIdentity in MVC3

    - by Steoates
    I've got my claims set-up with MVC3 using azure and everything is going well. What I need to do now is extend the Claims Identity that's in the current thread / http context and add my own information (DOB, Address.. that sort of stuff) so my question is - where is the best place to do this? any examples would be great.. I presume that when the user is authenticated id then have to go to the DB and pull back the relevant record for the user then add it to the custom Claims Identity object? cheers. ste.

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  • Is there a linear-time performance guarantee with using an Iterator?

    - by polygenelubricants
    If all that you're doing is a simple one-pass iteration (i.e. only hasNext() and next(), no remove()), are you guaranteed linear time performance and/or amortized constant cost per operation? Is this specified in the Iterator contract anywhere? Are there data structures/Java Collection which cannot be iterated in linear time? java.util.Scanner implements Iterator<String>. A Scanner is hardly a data structure (e.g. remove() makes absolutely no sense). Is this considered a design blunder? Is something like PrimeGenerator implements Iterator<Integer> considered bad design, or is this exactly what Iterator is for? (hasNext() always returns true, next() computes the next number on demand, remove() makes no sense). Similarly, would it have made sense for java.util.Random implements Iterator<Double>?

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  • General approach for posting business logic status messages to UI?

    - by generalt
    Hello all. I have been struggling with this question for awhile now, and I haven't reached a conclusion. I'm not typically a UI programmer, so forgive the noobishness. I'm writing a typical application with a UI layer (WPF) and a business layer. I want to post status messages to the UI from the business layer (perhaps deep within the business layer), but I don't want the business layer to have any knowledge of the UI. Is there a generally accepted pattern for this? I was thinking to have a message queue of some sort to which the business layer posts status messages, and have the view model of the UI subscribe to that queue and intercept messages from the queue and route them to the UI. Is that a good approach? Is there somewhere else I should start? Thank you.

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  • Rails: How do I run a before_save only if certain conditions are met?

    - by Shpigford
    I have a before_save method that I call that renames an uploaded image. before_save :randomize_file_name def randomize_file_name extension = File.extname(screen_file_name).downcase key = ActiveSupport::SecureRandom.hex(8) self.screen.instance_write(:file_name, "#{key}#{extension}") end That method is part of my Item model. That works great when I create a new item or need to update the image associated with an item...but the problem is that if I need to update an item but NOT the image, the randomize_file_name method still gets run and renames the file in the database (though not the file itself, obviously). So, I'm thinking I need to figure out a way to only run randomize_file_name if a file is included in the form submission...but I'm not sure how to pull that off.

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  • Multiple Rails forks with separate designs and layouts

    - by mettadore
    I have a Rails project that is basically a simple web app for a membership-based organization. We've open sourced the code on Github for the web app so that others can use it, but have a licensed design/layout that the original organization is going to use. This layout cannot be open sourced. I was wondering if others have run into the situation where you have an open-source Rails app with a non-OS design. My initial thought is to put app/views in .gitignore, and to have anyone forking the code add their own views directory, perhaps including an app/views_default directory with a web-app-theme layout or something else to get people running. Is this the best option (realizing that there are other files such as JavaScript, CSS, etc that come with the layout that must also be ignored). Does anyone have some good thoughts or pointers on this?

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  • Unique constraint on more than 10 columns

    - by tk
    I have a time-series simulation model which has more than 10 input variables. The number of distinct simulation instances would be more than 1 million, and each simulation instance generates a few output rows every day. To save the simulation result in a relational database, i designed tables like this. Table SimulationModel { simul_id : integer (primary key), input0 : string or numeric, input1 : string or numeric, ...} Table SimulationOutput { dt : DateTime (primary key), simul_id : integer (primary key), output0 : numeric, ...} My question is, is it fine to put an unique constraint on all of the input columns of SimulationModel table? If it is not a good idea, then what kind of other options do i have to make sure each model is unique?

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  • Pattern for iPhone background loading during init?

    - by Rob S.
    Hi everyone, I'm currently kicking off a background thread to do some REST queries in my app delegate's didFinishLaunchingWithOptions. This thread creates some objects and populates the model as the rest of the app continues to load (because I don't block, and didFinishLaunchingWithOptions returns YES). I also put up a loading UIViewController 'on top' of the main view that I tear down after the background initialization is complete. My problem is that I need to notify the first view (call it the Home view) that the model is ready, and that it should populate itself. The trick is that the background download could have finished before Home.viewDidAppear is called, or any of the other Home.initX methods. I'm having difficulty synchronizing all of this and I've thought about it long enough that it feels like I'm barking up the wrong tree. Are there any patterns here for this sort of thing? I'm sure other apps start by performing lengthy operations with loading screens :) Thanks!

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  • Adding a Categorylist to all pages with MVC4

    - by Sidriel
    I'm new with MVC4 and just MVC. I have a homecontroller and a categorycontroller. The categorycontroller sends data from the model to the categoryIndex view. That's works fine. But now I want to add the categorylist on all the available controllers. I already fixed this to add in all classes return view(db.categorys.ToList()); and add categoryIndex to the shared folder. In _layout.cshtml I'm adding a@RenderPage("~/")` and this works. But when I have to pass more than only the (db.categorys.ToList()) in the return it goes wrong. How can I fixed this problem. How do I add the categorylist too every controller and page properly?

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