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  • Best solution for a comment table for multiple content types

    - by KRTac
    I'm currently designing a comments table for a site I'm building. Users will be able to upload images, link videos and add audio files to the profile. Each of these types of content must be commentable. Now I'm wondering what's the best approach to this. My current options are: 1. to have one big comments table and a link tables for every content type (comments_videos, ...) with comment_id and _id. 2. to have comments separated by the type of content their for. So each type of content would have his own comments table with the comments for that type.

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  • Refactoring a C# derived class with method dependancies

    - by drelihan
    Hi Folks, I want to get your opinion on this. I have a class which is derived from a base class. I don't have control over the code in the base class and it is critical to the system that I derive from it. In my class I inherite two methods that are critical to the system and are used in pretty much every function, many times. I intend to refactor this derived class and extract some classes from it - this won't be a problem. What I'm not sure about is, is it worth extracting class if I have to constantly make call backs to my main class to access the two methods (or public wrappers to the methods)??? Thanks

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  • Factory Method Implementation

    - by cedar715
    I was going through the 'Factory method' pages in SO and had come across this link. And this comment. The example looked as a variant and thought to implement in its original way: to defer instantiation to subclasses... Here is my attempt. Does the following code implements the Factory pattern of the example specified in the link? Please validate and suggest if this has to undergo any re-factoring. public class ScheduleTypeFactoryImpl implements ScheduleTypeFactory { @Override public IScheduleItem createLinearScheduleItem() { return new LinearScheduleItem(); } @Override public IScheduleItem createVODScheduleItem() { return new VODScheduleItem(); } } public class UseScheduleTypeFactory { public enum ScheduleTypeEnum { CableOnDemandScheduleTypeID, BroadbandScheduleTypeID, LinearCableScheduleTypeID, MobileLinearScheduleTypeID } public static IScheduleItem getScheduleItem(ScheduleTypeEnum scheduleType) { IScheduleItem scheduleItem = null; ScheduleTypeFactory scheduleTypeFactory = new ScheduleTypeFactoryImpl(); switch (scheduleType) { case CableOnDemandScheduleTypeID: scheduleItem = scheduleTypeFactory.createVODScheduleItem(); break; case BroadbandScheduleTypeID: scheduleItem = scheduleTypeFactory.createVODScheduleItem(); break; case LinearCableScheduleTypeID: scheduleItem = scheduleTypeFactory.createLinearScheduleItem(); break; case MobileLinearScheduleTypeID: scheduleItem = scheduleTypeFactory.createLinearScheduleItem(); break; default: break; } return scheduleItem; } }

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  • What is the length of time to send a list of 200,000 integers from a client's browser to an internet

    - by indiehacker
    Over the connections that most people in the USA have in their homes, what is the approximate length of time to send a list of 200,000 integers from a client's browser to an internet sever (say Google app engine)? Does it change much if the data is sent from an iPhone? How does the length of time increase as the size of the integer list increases (say with a list of a million integers) ? Context: I wasn't sure if I should write code to do some simple computations and sorting of such lists for the browser in javascript or for the server in python, so I wanted to explore this issue of how long it takes to send the output data from a browser to a server over the web in order to help me decide where (client's browser or app engine server) is the best place for such computations to be processed.

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  • java Properties - to expose or not to expose?

    - by ring bearer
    This might be an age old problem and I am sure everyone has their own ways. Suppose I have some properties defined such as secret.user.id=user secret.password=password website.url=http://stackoverflow.com Suppose I have 100 different classes and places where I need to use these properties. Which one is good (1) I create a Util class that will load all properties and serve them using a key constant Such as : Util is a singleton that loads all properties and keeps up on getInstance() call. Util myUtil = Util.getInstance(); String user = myUtil.getConfigByKey(Constants.SECRET_USER_ID); String password = myUtil.getConfigByKey(Constants.SECRET_PASSWORD); .. //getConfigByKey() - inturns invokes properties.get(..) doSomething(user, password) So wherever I need these properties, I can do steps above. (2) I create a meaningful Class to represent these properties; say, ApplicationConfig and provide getters to get specific properties. So above code may look like: ApplicationConfig config = ApplicationConfig.getInstance(); doSomething(config.getSecretUserId(), config.getPassword()); //ApplicationConfig would have instance variables that are initialized during // getInstance() after loading from properties file. Note: The properties file as such will have only minor changes in the future. My personal choice is (2) - let me hear some comments?

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  • What are appropriate ways to represent relationships between people in a database table?

    - by Emilio
    I've got a table of people - an ID primary key and a name. In my application, people can have 0 or more real-world relationships with other people, so Jack might "work for" Jane and Tom might "replace" Tony and Bob might "be an employee of" Rob and Bob might also "be married to" Mary. What's the best way to represent this in the database? A many to many intersect table? A series of self joins? A relationship table with one row per relationship pair and type, where I insert records for the relationship in both directions?

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  • Validation with State Pattern for Multi-Page Forms in ASP.NET

    - by philrabin
    I'm trying to implement the state pattern for a multi-page registration form. The data on each page will be accumulated and stored in a session object. Should validation (including service layer calls to the DB) occur on the page level or inside each state class? In other words, should the concrete implementation of IState be concerned with the validation or should it be given a fully populated and valid object? See "EmptyFormState" class below: namespace Example { public class Registrar { private readonly IState formEmptyState; private readonly IState baseInformationComplete; public RegistrarSessionData RegistrarSessionData { get; set;} public Registrar() { RegistrarSessionData = new RegistrarSessionData(); formEmptyState = new EmptyFormState(this); baseInformationComplete = new BasicInfoCompleteState(this); State = formEmptyState; } public IState State { get; set; } public void SubmitData(RegistrarSessionData data) { State.SubmitData(data); } public void ProceedToNextStep() { State.ProceedToNextStep(); } } //actual data stored in the session //to be populated by page public class RegistrarSessionData { public string FirstName { get; set; } public string LastName { get; set; } //will include values of all 4 forms } //State Interface public interface IState { void SubmitData(RegistrarSessionData data); void ProceedToNextStep(); } //Concrete implementation of IState //Beginning state - no data public class EmptyFormState : IState { private readonly Registrar registrar; public EmptyFormState(Registrar registrar) { this.registrar = registrar; } public void SubmitData(RegistrarSessionData data) { //Should Validation occur here? //Should each state object contain a validation class? (IValidator ?) //Should this throw an exception? } public void ProceedToNextStep() { registrar.State = new BasicInfoCompleteState(registrar); } } //Next step, will have 4 in total public class BasicInfoCompleteState : IState { private readonly Registrar registrar; public BasicInfoCompleteState(Registrar registrar) { this.registrar = registrar; } public void SubmitData(RegistrarSessionData data) { //etc } public void ProceedToNextStep() { //etc } } }

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  • Designer tool integration with TFS?

    - by reallyJim
    Are there good tools for professional designers to use that support source control integration with Team Foundation Server? I'm aware of the Expression tools, but curious to see if there is something else, as proper designer tools really aren't my area of expertise.

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  • What situations does a Monostate pattern model?

    - by devoured elysium
    I know what both a Singleton or a Monostate are and how to implement them. Although I can see many uses for a Singleton, I can't imagine a situation where I would want to let the user create as many instances of my class although in reality only one really exists behind the scenes. Can anybody help me here? I know that for several reasons one should stay away from both patterns, but in theory, what kind of problems does the Monostate model? Thanks

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  • Data access pattern, combining push and pull?

    - by andlju
    I need some advice on what kind of pattern(s) I should use for pushing/pulling data into my application. I'm writing a rule-engine that needs to hold quite a large amount of data in-memory in order to be efficient enough. I have some rather conflicting requirements; It is not acceptable for the engine to always have to wait for a full pre-load of all data before it is functional. Only fetching and caching data on-demand will lead to the engine taking too long before it is running quickly enough. An external event can trigger the need for specific parts of the data to be reloaded. Basically, I think I need a combination of pushing and pulling data into the application. A simplified version of my current "pattern" looks like this (in psuedo-C# written in notepad): // This interface is implemented by all classes that needs the data interface IDataSubscriber { void RegisterData(Entity data); } // This interface is implemented by the data access class interface IDataProvider { void EnsureLoaded(Key dataKey); void RegisterSubscriber(IDataSubscriber subscriber); } class MyClassThatNeedsData : IDataSubscriber { IDataProvider _provider; MyClassThatNeedsData(IDataProvider provider) { _provider = provider; _provider.RegisterSubscriber(this); } public void RegisterData(Entity data) { // Save data for later StoreDataInCache(data); } void UseData(Key key) { // Make sure that the data has been stored in cache _provider.EnsureLoaded(key); Entity data = GetDataFromCache(key); } } class MyDataProvider : IDataProvider { List<IDataSubscriber> _subscribers; // Make sure that the data for key has been loaded to all subscribers public void EnsureLoaded(Key key) { if (HasKeyBeenMarkedAsLoaded(key)) return; PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } // Force all subscribers to get a new version of the data for key public void ForceReload(Key key) { PublishDataToSubscribers(key); MarkKeyAsLoaded(key); } void PublishDataToSubscribers(Key key) { Entity data = FetchDataFromStore(key); foreach(var subscriber in _subscribers) { subscriber.RegisterData(data); } } } // This class will be spun off on startup and should make sure that all data is // preloaded as quickly as possible class MyPreloadingThread { IDataProvider _provider; MyPreloadingThread(IDataProvider provider) { _provider = provider; } void RunInBackground() { IEnumerable<Key> allKeys = GetAllKeys(); foreach(var key in allKeys) { _provider.EnsureLoaded(key); } } } I have a feeling though that this is not necessarily the best way of doing this.. Just the fact that explaining it seems to take two pages feels like an indication.. Any ideas? Any patterns out there I should have a look at?

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  • Best practice for DAO pattern ?

    - by Tony
    I've seen a lot of codes use a service-dao pattern , I don't know the origin of this pattern . It force the front layer call service , then delegates some of the service task to dao. I want to ask : Does DAO layer do purely data access related task ? What about exception encapsulation ? Is there other pattern can be used to replace this ?

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  • Need help to create database schema for wholesale online tee store

    - by techiepark
    Hi, I'm currently working on wholesale online t-shirt shop. I have done this for fixed quantity and price, and its working fine. Now i need to do this for variable quantity and price. Here is the reference link, like what i have to do. Basic tables i have created are - CREATE TABLE attribute ( attribute_id int(11) NOT NULL auto_increment, name varchar(100) NOT NULL, PRIMARY KEY (attribute_id) ); CREATE TABLE attribute_value ( attribute_value_id int(11) NOT NULL auto_increment, attribute_id int(11) NOT NULL, value varchar(100) NOT NULL, PRIMARY KEY (attribute_value_id), KEY idx_attribute_value_attribute_id (attribute_id) ); CREATE TABLE product ( product_id int(11) NOT NULL auto_increment, name varchar(100) NOT NULL, description varchar(1000) NOT NULL, price decimal(10,2) NOT NULL, image varchar(150) default NULL, thumbnail varchar(150) default NULL, PRIMARY KEY (product_id), FULLTEXT KEY idx_ft_product_name_description (name,description) ); CREATE TABLE product_attribute ( product_id int(11) NOT NULL, attribute_value_id int(11) NOT NULL, PRIMARY KEY (product_id,attribute_value_id) ); I'm not getting how to store the price based on variable quantity. Please help me to create product and its related tables. my requirement is same as above reference link.

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  • How to make this OO?

    - by John
    Hello, Sorry for the poor title,I'm new to OOP so I don't know what is the term for what I need to do. I have, say, 10 different Objects that inherit one Object.They have different amount and type of class members,but all of them have one property in common - Visible. type TObj1=class(TObject) private a:integer; ...(More members) Visible:Boolean; end; TObj2=class(TObject) private b:String; ...(More members) Visible:Boolean; end; ...(Other 8 objects) For each of them I have a variable. var Obj1:TObj1; Obj2:TObj2; Obj3:TObj3; ....(Other 7 objects) Rule 1: Only one object can be initialized at a time(others have to be freed) to be visible. For this rule I have a global variable var CurrentVisibleObj:TObject; //Because they all inherit TObject Finally there is a procedure that changes visibility. procedure ChangeObjVisibility(newObj:TObject); begin CurrentVisibleObj.Free; //Free the old object CurrentVisibleObj:=newObj; //assign the new object CurrentVisibleObj:= ??? //Create new object CurrentVisibleObj.Visible:=true; //Set visibility to new object end; There is my problem,I don't know how to initialize it,because the derived class is unknown. How do I do this? I simplified the explanation,in the project there are TFrames each having different controls and I have to set visible/not visible the same way(By leaving only one frame initialized). Sorry again for the title,I'm very new to OOP.

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  • add schema to path in postgresql

    - by veilig
    I'm the process of moving applications over from all in the public schema to each having their own schema. for each application, I have a small script that will create the schema and then create the tables,functions,etc... to that schema. Is there anyway to automatically add a newly created schema to the search_path? Currently, the only way I see is to find the users current path SHOW search_path; and then add the new schema to it SET search_path to xxx,yyy,zzz; I would like some way to just say, append schema zzz to the users_search path. is this possible?

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  • DDD and MVC: Difference between 'Model' and 'Entity'

    - by Nathan Loding
    I'm seriously confused about the concept of the 'Model' in MVC. Most frameworks that exist today put the Model between the Controller and the database, and the Model almost acts like a database abstraction layer. The concept of 'Fat Model Skinny Controller' is lost as the Controller starts doing more and more logic. In DDD, there is also the concept of a Domain Entity, which has a unique identity to it. As I understand it, a user is a good example of an Entity (unique userid, for instance). The Entity has a life-cycle -- it's values can change throughout the course of the action -- and then it's saved or discarded. The Entity I describe above is what I thought Model was supposed to be in MVC? How off-base am I? To clutter things more, you throw in other patterns, such as the Repository pattern (maybe putting a Service in there). It's pretty clear how the Repository would interact with an Entity -- how does it with a Model? Controllers can have multiple Models, which makes it seem like a Model is less a "database table" than it is a unique Entity. So, in very rough terms, which is better? No "Model" really ... class MyController { public function index() { $repo = new PostRepository(); $posts = $repo->findAllByDateRange('within 30 days'); foreach($posts as $post) { echo $post->Author; } } } Or this, which has a Model as the DAO? class MyController { public function index() { $model = new PostModel(); // maybe this returns a PostRepository? $posts = $model->findAllByDateRange('within 30 days'); while($posts->getNext()) { echo $posts->Post->Author; } } } Both those examples didn't even do what I was describing above. I'm clearly lost. Any input?

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  • Is it a good idea to cache data from web services into a database?

    - by Thierry Lam
    Let's assume that Stackoverflow offers web services where you can retrieve all the questions asked by a specific user. A request to get all question from user A can result in the following json output: { { "question": "What is rest?", "date_created": "20/02/2010", "votes": 1, }, { "question": "Which database to use for ...", "date_created": "20/07/2009", "votes": 5, }, } If I want to manipulate and present the data in any ways that I want, will it be wise to dump it in a local database? At some point, I will also want to retrieve all answers for each question and store them in a local database. The workflow that I'm thinking is: User logs in. Web services retrieve all questions asked by the logged in user, dump them in a local database. User wants all answers for a specific question, another web service does the retrieval and dump them in a local database. After user logs out, delete from the local database all questions and answers from that user.

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  • Is ASP.NET MVC is really MVC? Or how to separate model from controller?

    - by Andrey
    Hi all, This question is a bit rhetorical. At some point i got a feeling that ASP.NET MVC is not that authentic implementation of MVC pattern. Or i didn't understood it. Consider following domain: electric bulb, switch and motion detector. They are connected together and when you enter the room motion detector switches on the bulb. If i want to represent them as MVC: switch is model, because it holds the state and contains logic bulb is view, because it presents the state of model to human motion detector is controller, because it converts user actions to generic model commands Switch has one private field (On/Off) as a State and two methods (PressOn, PressOff). If you call PressOn when it is Off it goes to On, if you call it again state doesn't change. Bulb can be replaced with buzzer, motion detector with timer or button, but the model still represent the same logic. Eventually system will have same behavior. This is how i understand classical MVC decomposition, please correct me if i am wrong. Now let's decompose it in ASP.Net MVC way. Bulb is still a view Controller will be switch + motion detector Model is some object that will just pass state to bulb. So the logic that defines behavior moves to controller. Question 1: Is my understanding of MVC and ASP.NET MVC correct? Question 2: If yes, do you agree that ASP.NET MVC is not 100% accurate implementation? And back to life. The final question is how to separate model from controller in case of ASP.NET MVC. There can be two extremes. Controller does basic stuff and call model to do all the logic. Another is controller does all the logic and model is just something like class with properties that is mapped to DB. Question 3: Where should i draw the line between this extremes? How to balance? Thanks, Andrey

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  • how to run this qt script? (newbie question)

    - by GB_J
    I have a qt script(barchart.qs) that creates a graph for me. I don't know how i can incorporate(ie show the graph) in my qt mainwindow. Can some one please help me look at the code and what its outputs are? I tried engine.evaluate, but i do not know what is the QScriptValue i'm getting in return. Thanks sooo much. This is the script: BarChart.prototype = new QWidget; BarChart.prototype.suffix = ""; function BarChart(parent) { QWidget.call(this, parent); } // find the maximum value and widest (pixel-wise) label and suffix BarChart.prototype.showEvent = function(event) { var fm = new QFontMetrics(this); this.margin = 20; this.titleHeight = fm.height(); this.barHeight = 1.5 * fm.height(); this.barSpacing = 0.6 * fm.height(); this.maxValue = this.suffixWidth = this.labelWidth = 0; var count = 0; for (d in this.data) { this.labelWidth = Math.max(this.labelWidth, fm.width(d)); this.maxValue = Math.max(this.maxValue, this.data[d]); this.suffixWidth = Math.max(this.suffixWidth, fm.width(String(this.data[d]) + " " + this.suffix)); count++; } this.startHue = 15; this.hueDelta = 360 / count; this.size = new QSize(640, this.titleHeight + 2 * this.margin + (this.barHeight + this.barSpacing) * count); } BarChart.prototype.paintEvent = function(event) { var p = new QPainter; p.begin(this); // background and title p.fillRect(this.rect, new QBrush(new QColor(255, 255, 255))); p.drawText(0, 0, this.width, this.margin + this.titleHeight, Qt.AlignCenter, this.windowTitle, 0); var ofs = this.labelWidth + this.margin; var ww = this.width - this.suffixWidth - ofs - 2 * this.margin; var hue = this.startHue; var y = 0; p.translate(this.margin, this.titleHeight + 1.5 * this.margin); for (d in this.data) { // label on the left side p.setPen(new QColor(Qt.black)); p.drawText(0, y, this.labelWidth, this.barHeight, Qt.AlignVCenter + Qt.AlignRight, d, 0); // the colored bar var gradient = new QLinearGradient(new QPoint(ofs, y), new QPoint(ofs, y + this.barHeight)); gradient.setColorAt(0, QColor.fromHsv(hue, 255, 240)); gradient.setColorAt(1, QColor.fromHsv(hue, 255, 92)); p.setBrush(new QBrush(gradient)); p.setPen(new QColor(96, 96, 96)); var bw = this.data[d] * ww / this.maxValue; p.drawRect(ofs, y, bw, this.barHeight); // extra text at the end of the bar var text = new String(this.data[d] + " " + this.suffix); p.setPen(new QColor(Qt.black)); p.drawText(ofs + bw + this.margin/2, y, this.suffixWidth, this.barHeight, Qt.AlignVCenter + Qt.AlignLeft, text, 0); // for the next bar y += (this.barHeight + this.barSpacing); hue += this.hueDelta; if (hue >= 360) hue -= 360; } p.end(); } BarChart.prototype.wheelEvent = function(event) { this.startHue += event.delta() / 8 / 5; if (this.startHue = 360) this.startHue -= 360; if (this.startHue < 0) this.startHue += 360; this.update(); event.ignore(); } BarChart.prototype.mousePressEvent = function(event) { var fname = QFileDialog.getSaveFileName(this, "Save", ".", "*.png", 0, 0); if (fname.length > 0) { var img = new QImage(this.size, QImage.Format_ARGB32_Premultiplied); this.render(img); img.save(new QFile(fname)); } } var chart = new BarChart; chart.windowTitle = "Monthly"; chart.suffix = "reports"; chart.data = { "September" : 45, "October" : 60, "November" : 56, "December" : 0 }; chart.show(); QCoreApplication.exec();

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