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  • database modeling for google app engine for multiple revison of entity.

    - by iamgopal
    hi, in my application ( kind of wiki clone ) - an article is frequently changing. and i need to track all changes that are done on that article. { text only. } one crude way i have done it, is to add a datetime property and create a new entity everytime something change. which is too much database wasting. { and also un-necessary index waste too. } and also need to re-create parent-child and entity relationships. i also have log which can show changes -- but i want some thing easier , so that jumping from one version to another version could be easier. ideas ? thanks.

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  • How would you structure your entity model for storing arbitrary key/value data with different data t

    - by Nathan Ridley
    I keep coming across scenarios where it will be useful to store a set of arbitrary data in a table using a per-row key/value model, rather than a rigid column/field model. The problem is, I want to store the values with their correct data type rather than converting everything to a string. This means I have to choose either a single table with multiple nullable columns, one for each data type, or a set of value tables, one for each data type. I'm also unsure as to whether I should use full third normal form and separate the keys into a separate table, referencing them via a foreign key from the value table(s), or if it would be better to keep things simple and store the string keys in the value table(s) and accept the duplication of strings. Old/bad: This solution makes adding additional values a pain in a fluid environment because the table needs to be modified regularly. MyTable ============================ ID Key1 Key2 Key3 int int string date ---------------------------- 1 Value1 Value2 Value3 2 Value4 Value5 Value6 Single Table Solution This solution allows simplicity via a single table. The querying code still needs to check for nulls to determine which data type the field is storing. A check constraint is probably also required to ensure only one of the value fields contains non-nulll data. DataValues ============================================================= ID RecordID Key IntValue StringValue DateValue int int string int string date ------------------------------------------------------------- 1 1 Key1 Value1 NULL NULL 2 1 Key2 NULL Value2 NULL 3 1 Key3 NULL NULL Value3 4 2 Key1 Value4 NULL NULL 5 2 Key2 NULL Value5 NULL 6 2 Key3 NULL NULL Value6 Multiple-Table Solution This solution allows for more concise purposing of each table, though the code needs to know the data type in advance as it needs to query a different table for each data type. Indexing is probably simpler and more efficient because there are less columns that need indexing. IntegerValues =============================== ID RecordID Key Value int int string int ------------------------------- 1 1 Key1 Value1 2 2 Key1 Value4 StringValues =============================== ID RecordID Key Value int int string string ------------------------------- 1 1 Key2 Value2 2 2 Key2 Value5 DateValues =============================== ID RecordID Key Value int int string date ------------------------------- 1 1 Key3 Value3 2 2 Key3 Value6 How do you approach this problem? Which solution is better? Also, should the key column be separated into a separate table and referenced via a foreign key or be should it be kept in the value table and bulk updated if for some reason the key name changes?

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  • Unexpected space between DIV elements

    - by jon
    my code for the php page displaying the divs <?php session_start(); require_once("classlib/mainspace.php"); if (isset($_SESSION['username'])==FALSE) { header("location:login.php"); } $user = new User($_SESSION['username']); ?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="style/style.css" /> <title>SimpleTask - Home</title> </head> <body> <div id="main"> <div id="menu"> <div id="items"> <ul> <li><a href="home.php">home</a></li> <li>&bull;</li> <li><a href="projects.php">my projects</a></li> <li>&bull;</li> <li><a href="comments.php">my comments</a></li> </ul> </div> <div id="user"> <p>Welcome, <?php echo $user->GetRealName(); ?><br/><a href="editprofile.php">edit profile</a> &bull; <a href="logout.php">logout</a></p> </div> </div> <div id="content"> <h1>HOME</h1> </div> <div id="footer"> <p>footer text goes here here here here</p> </div> </div> </body> </html> and you can find my CSS here http://tasker.efficaxdevelopment.com/style/style.css and to view the live page go here http://tasker.efficaxdevelopment.com/login.php username:admin password:password

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  • What is the MVC version of this code?

    - by Ian Boyd
    i'm trying to wrap my head around how to enterprise up my code: taking a simple routine and splitting it up into 5 or 6 methods in 3 or 4 classes. i quickly came up three simple examples of code how i currently write it. Could someone please convert these into an MVC/MVP obfuscated version? Example 1: The last name is mandatory. Color the text box red if nothing is entered. Color it green if stuff is entered: private void txtLastname_TextChanged(object sender, EventArgs e) { //Lastname mandatory. //Color pinkish if nothing entered. Greenish if entered. if (txtLastname.Text.Trim() == "") { //Lastname is required, color pinkish txtLastname.BackColor = ControlBad; } else { //Lastname entered, remove the coloring txtLastname.BackColor = ControlGood; } } Example 2: The first name is optional, but try to get it. We'll add a bluish tint to this "try to get" field: private void txtFirstname_TextChanged(object sender, EventArgs e) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (txtFirstname.Text == "") { //Nothing there, hint it blue txtFirstname.BackColor = ControlRequired; } else if (txtFirstname.Text.Trim() == "") { //They entered spaces - bad user! txtFirstname.BackColor = ControlBad; } else { //Entered stuff, remove coloring txtFirstname.BackColor = SystemColors.Window; } } Example 3 The age is totally optional. If an age is entered, it better be valid: private void txtAge_TextChanged(object sender, EventArgs e) { //Age is optional, but if entered it better be valid int nAge = 0; if (Int32.TryParse(txtAge.Text, out nAge)) { //Valid integer entered if (nAge < 0) { //Negative age? i don't think so txtAge.BackColor = ControlBad; } else { //Valid age entered, remove coloring txtAge.BackColor = SystemColors.Window; } } else { //Whatever is in there: it's *not* a valid integer, if (txtAge.Text == "") { //Blank is okay txtAge.BackColor = SystemColors.Window; } else { //Not a valid age, bad user txtAge.BackColor = ControlBad; } } } Every time i see MVC code, it looks almost like random splitting of code into different methods, classes, and files. i've not been able to determine a reason or pattern to their madness. Without any understanding of they why it's being one some way, it makes no sense. And using the words model, view, controller and presenter, like i'm supposed to know what that means, doesn't help. The model is your data. The view shows data on screen. The controller is used to carry out the users actions And oranges taste orangy. Here's my attempt at splitting things up in order to make the code more difficult to follow. Is this anywhere close to MVC? private void txtFirstname_TextChanged(object sender, EventArgs e) { FirstnameTextChangedHandler(sender, e); } private void FirstnameTextChangedHandler(sender, e) { string firstname = GetFirstname(); Color firstnameTextBoxColor = GetFirstnameTextBoxColor(firstname); SetFirstNameTextBoxColor(firstnameTextBoxColor); } private string GetFirstname() { return txtFirstname.Text; } private Color GetFirstnameTextBoxColor(string firstname) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (firstname == "") { //Nothing there, hint it blue return GetControlRequiredColor(); } else if (firstname.Trim() == "") { //They entered spaces - bad user! return GetControlBadColor(); } else { //Entered stuff, remove coloring return GetControlDefaultColor(); } } private Color GetControlRequiredColor() { return ControlRequired; } private Color GetControlBadColor() { return ControlBad; } private Color GetControlGoodColor() { return ControlGood; } //am i doin it rite i've obfuscated the code, but it's still altogether. The next step in the MVC obfuscation, i gather, is to hide the code in 3 or 4 different files. It's that next step that i don't understand. What is the logical separation of which functions are moved into what other classes? Can someone translate my 3 simple examples above into full fledged MVC obfuscation? Edit: Not ASP/ASP.NET/Online. Pretend it's on a desktop, handheld, surface, kiosk. And pretend it's language agnostic.

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  • Better alternative to autonumber primary keys

    - by Comrad_Durandal
    I am looking for a better primary key than the autonumber data type, namely for the reason that it's limited to a long integer, when I really just need the field to reflect a number or text string that will never ever repeat, no matter HOW many records are added or deleted from the table. The problem is I am not sure how to implement something like turning the current date and time into a hexadecimal string and using that as a unique field I can use as a primary key. Am I just being too paranoid about running out of space?

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  • What is the best way to store categorical references in SQL tables?

    - by jlafay
    I'm wanting to store a wide array of categorical data in MySQL database tables. Let's say that for instance I want to to information on "widgets" and want to categorize attributes in certain ways, i.e. shape category. For instance, the widgets could be classified as: round, square, triangular, spherical, etc. Should these categories be stored within a table to reference them best from an application? Another possibility, I would imagine, would be to add a column to widgets that contained a shape column that contained a tiny int. That way my application could search shapes by that and then use a coordinating enum type that would map the shape int meanings. Which would be best? Or is there another solution that I'm not thinking of yet?

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  • When to define SDD operations System->Actor?

    - by devoured elysium
    I am having some trouble understanding how to make SDDs, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The user tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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  • Fastest way to do a weighted tag search in SQL Server

    - by Hasan Khan
    My table is as follows ObjectID bigint Tag nvarchar(50) Weight float Type tinyint I want to get search for all objects that has tags 'big' or 'large' I want the objectid in order of sum of weights (so objects having both the tags will be on top) select objectid, row_number() over (order by sum(weight) desc) as rowid from tags where tag in ('big', 'large') and type=0 group by objectid the reason for row_number() is that i want paging over results. The query in its current form is very slow, takes a minute to execute over 16 million tags. What should I do to make it faster? I have a non clustered index (objectid, tag, type) Any suggestions?

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  • ASP.NET MVC Filters: How to set Viewdata for Dropdown based on action parameter

    - by CRice
    Hi, Im loading an entity 'Member' from its id in route data. [ListItemsForMembershipType(true)] public ActionResult Edit(Member someMember) {...} The attribute on the action loads the membership type list items for a dropdown box and sticks it in viewdata. This is fine for add forms, and search forms (it gets all active items) but I need the attribute to execute BASED ON THE VALUE someMember.MembershipTypeId, because its current value must always be present when loading the item (i.e. all active items, plus the one from the loaded record). So the question is, what is the standard pattern for this? How can my attribute accept the value or should I be loading the viewdata for the drop down in a controller supertype or during model binding or something else? It is in an attribute now because the code to set the viewdata would otherwise be duplicated in each usage in each action.

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  • How to evade writing a lot of repetitive code when mapping?

    - by JPCF
    I have a data access layer (DAL) using Entity Framework, and I want to use Automapper to communicate with upper layers. I will have to map data transfer objects (DTOs) to entities as the first operation on every method, process my inputs, then proceed to map from entities to DTOs. What would you do to skip writing this code? As an example, see this: //This is a common method in my DAL public CarDTO getCarByOwnerAndCreditStatus(OwnerDTO ownerDto, CreditDto creditDto) { //I want to automatize this code on all methods similar to this Mapper.CreateMap<OwnerDTO,Owner>(); Mapper.CreateMap<CreditDTO,Credit>(); Owner owner = Mapper.map(ownerDto); Owner credit = Mapper.map(creditDto) //... Some code processing the mapped DTOs //I want to automatize this code on all methods similar to this Mapper.CreateMap<Car,CarDTO>(); Car car = Mapper.map(ownedCar); return car; }

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  • Single-Page Web Apps: Client-side datastores & server persistence

    - by fig-gnuton
    How should client-side datastores & persistence be handled in a single-page web application? Global vars vs. DI/IoC: Should datastores be assigned to global variables so any part of the application can access them? Or should they be dependency injected where required? Server persistence: Assuming a datastore's data needn't always be persisted to the server immediately, should the datastore itself handle persistence? If not, then what class should handle persistence and how should the persistence class fit into the client-side architecture overall? Is the datastore considered the model in MVC, or is it something else since it just stores raw data?

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  • Recommendation for tool/framework that follows the naked objects pattern?

    - by Marcus Munzert
    I am searching for a tool/framework that follows the naked objects pattern and is written in Java. I know about tools like for instance JMatter, Naked Objects and Domain Object Explorer. That's not exactly what I am searching for, though. Open source would be great, but doesn't need to be. My intention is to use that tool/framework for the purpose of model-driven software development to do the modeling part. Ideally, such a tool/framework would provide the option to use JPA to store/load objects.

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  • Table with unequal rows in XUL layout

    - by Michael
    Trying to get something similar for Firefox extension using XUL. The most difficult part is the grid with unequal number of rows. I tried <grid> but it didn't work well. Also don't want to use HTML inside of XUL. Any ideas how to build such table?

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  • Where should my "filtering" logic reside with Linq-2-SQL and ASP.NET-MVC in View or Controller?

    - by Nate Bross
    I have a main Table, with several "child" tables. TableA and TableAChild1 and TableAChild2. I have a view which shows the information in TableA, and then has two columns of all items in TableAChild1 and TableAChild2 respectivly, they are rendered with Partial views. Both child tables have a bit field for VisibleToAll, and depending on user role, I'd like to either display all related rows, or related rows where VisibleToAll = true. This code, feels like it should be in the controller, but I'm not sure how it would look, because as it stands, the controller (limmited version) looks like this: return View("TableADetailView", repos.GetTableA(id)); Would something like this be even work, and would it be bad what if my DataContext gets submitted, would that delete all the rows that have VisibleToAll == false? var tblA = repos.GetTableA(id); tblA.TableAChild1 = tblA.TableAChild1.Where(tmp => tmp.VisibleToAll == true); tblA.TableAChild2 = tblA.TableAChild2.Where(tmp => tmp.VisibleToAll == true); return View("TableADetailView", tblA); It would also be simple to add that logic to the RendarPartial call from the main view: <% Html.RenderPartial("TableAChild1", Model.TableAChild1.Where(tmp => tmp.VisibleToAll == true); %>

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  • Define "Validation in the Model"

    - by sunwukung
    There have been a couple of discussions regarding the location of user input validation: http://stackoverflow.com/questions/659950/should-validation-be-done-in-form-objects-or-the-model http://stackoverflow.com/questions/134388/where-do-you-do-your-validation-model-controller-or-view These discussions were quite old, so I wanted to ask the question again to see if anyone had any fresh input. If not, I apologise in advance. If you come from the Validation in the Model camp - does Model mean OOP representation of data (i.e. Active Record/Data Mapper) as "Entity" (to borrow the DDD terminology) - in which case you would, I assume, want all Model classes to inherit common validation constraints. Or can these rules simply be part of a Service in the Model - i.e. a Validation service? For example, could you consider Zend_Form and it's validation classes part of the Model? The concept of a Domain Model does not appear to be limited to Entities, and so validation may not necessarily need to be confined to this Entities. It seems that you would require a lot of potentially superfluous handing of values and responses back and forth between forms and "Entities" - and in some instances you may not persist the data recieved from user input, or recieve it from user input at all.

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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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  • Responsive logo (image replacement) in html5boilerplate

    - by Barbara
    I'm using the responsive version of html5 boilerplate via initializr.com. My site uses a custom logo so i added the .ir class to h1 .ir { background-color: transparent; border: 0; overflow: hidden; *text-indent: -9999px; } like this <h1 class="title ir">h1.title</h1> The documentation says Add the .ir class to any element you are applying image-replacement to. When replacing an element's content with an image, make sure to also set a specific background-image: url(pathtoimage.png);, width, and height so that your replacement image appears. So I added to the code these lines .ir { background-image: url(http://i.imgur.com/yYnyJ.jpg); background-size: 100% auto; width:450px; height:450px } The problem are the specific width and height. I can't get rid of them but the logo is not responsive this way. Ideas? Here's the fiddle. http://jsfiddle.net/qeW3e/

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  • New or not so well-known paradigms, syntax features and behaviours of programming languages?

    - by George B
    I've designed some educational programming languages and interpreters for them, but my problem always was that they ended up "normal" and "boring", mostly similar to some kind of existing language (ASM and BASIC). I find it really hard to come up with new ideas for syntax features, "neat things" and new or very modified programming paradigms for it. I always thought that it was hard to come up with good new things not fun/useless new things for this case. I wondered if you could help me out with your creativity: What features in terms of language syntax and built-in functions as well as maybe even new paradigms can I work into my language to keep it useless but more fun, enjoyable, interesting and/or different to program in?

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  • How would I implement separate databases for reading and writing operations?

    - by Matt
    I am interested in implementing an architecture that has two databases one for read operations and the other for writes. I have never implemented something like this and have always built single database, highly normalised systems so I am not quite sure where to begin. I have a few parts to this question. 1. What would be a good resource to find out more about this achitecture? 2. Is it just a question of replicating between two identical schemas, or would your schemas differ depending on the operations, would normalisation vary too? 3. How do you insure that data written to one database is immediately available for reading from the second? Any further help, tips, resources would be appreciated. Thanks.

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  • What are the common patterns in web programming?

    - by lankerisms
    I have been trying to write my first big web app (more than one cgi file) and as I kept moving forward with the rough prototype, paralelly trying to predict more tasks, this is the todo that got accumulated (In no particular order). * Validations and input sanitizations * Object versioning (to avoid edit conflicts. I dont want hard locks) * Exception handling * memcache * xss and injection protections * javascript * html * ACLs * phonetics in search, match and find duplicates (for form validation) * Ajaxify!!! (I have snipped off the project specific items.) I know that each todo will be quite tied up to its project and technologies used. What I am wondering though, is if there is a pattern in your todo items as well as the sequence in which you experienced guys have come across them.

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  • Why doesn't Java Map extends Collection?

    - by polygenelubricants
    I was surprised by the fact that Map<?,?> is not a Collection<?>. I thought it'd make a LOT of sense if it was declared as such: public interface Map<K,V> extends Collection<Map.Entry<K,V>> After all, a Map<K,V> is a collection of Map.Entry<K,V>, isn't it? So is there a good reason why it's not implemented as such?

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  • How do you unit test new code that uses a bunch of classes that cannot be instantiated in a test har

    - by trendl
    I'm writing a messaging layer that should handle communication with a third party API. The API has a bunch of classes that cannot be easily (if at all) instantiated in a test harness. I decided to wrap each class that I need in my unit tests with an adapter/wrapper and expose the members I need through this adapter class. Often I need to expose the wrapped type as well which I do by exposing it as an object. I have also provided an interface for for each or the adapter classes to be able to use them with a mocking framework. This way I can substitute the classes in test for whatever I need. The downside is that I have a bunch of adapter classes that so far server no other reason but testing. For me this is a good reason by itself but others may find this not enough. Possibly, when I write an implementation for another third party vendor's API, I may be able to reuse much of my code and only provide the adapters specific to the vendor's API. However, this is a bit of a long shot and I'm not actually sure it will work. What do you think? Is this approach viable or am I writing unnecessary code that serves no real purpose? Let me say that I do want to write unit tests for my messaging layer and I do now know how to do it otherwise.

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  • Command Query Separation validating for retries

    - by Neil Barnwell
    So I'm comfortable with the basic concept of CQS, where you might have a command that writes to one database, and that updates the query database that you read from. However, consider the scenario where you are entering data, and want to prevent duplicates. Using new employee data entry an employee register as an example, working through a pile of application forms to key in the new employees' details: Take top sheet. Key in employee name and unique payroll number to UI. Submit. Put paper in "completed pile". Repeat. How would you now prevent the user from keying in the same payroll number again, say for instance if they get distracted and can't remember whether they've keyed one in already and the "message" hasn't got all the way back to the query db for the user to search?

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