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  • Should I define a single "DataContext" and pass references to it around or define muliple "DataConte

    - by Nate Bross
    I have a Silverlight application that consists of a MainWindow and several classes which update and draw images on the MainWindow. I'm now expanding this to keep track of everything in a database. Without going into specifics, lets say I have a structure like this: MainWindow Drawing-Surface Class1 -- Supports Drawing DataContext + DataServiceCollection<T> w/events Class2 -- Manages "transactions" (add/delete objects from drawing) Class3 Each "Class" is passed a reference to the Drawing Surface so they can interact with it independently. I'm starting to use WCF Data Services in Class1 and its working well; however, the other classes are also going to need access to the WCF Data Services. (Should I define my "DataContext" in MainWindow and pass a reference to each child class?) Class1 will need READ access to the "transactions" data, and Class2 will need READ access to some of the drawing data. So my question is, where does it make the most sense to define my DataContext? Does it make sense to: Define a "global" WCF Data Service "Context" object and pass references to that in all of my subsequent classes? Define an instance of the "Context" for each Class1, Class2, etc Have each method that requires access to data define its own instance of the "Context" and use closures handle the async load/complete events? Would a structure like this make more sense? Is there any danger in keeping an active "DataContext" open for an extended period of time? Typical usecase of this application could range from 1 minute to 40+ minutes. MainWindow Drawing-Surface DataContext Class1 -- Supports Drawing DataServiceCollection<DrawingType> w/events Class2 -- Manages "transactions" (add/delete objects from drawing) DataServiceCollection<TransactionType> w/events Class3 DataServiceCollection<T> w/events

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  • What is the advantage of the 'src/main/java'' convention?

    - by Chris
    I've noticed that a lot of projects have the following structure: Project-A bin lib src main java RootLevelPackageClass.java I currently use the following convention (as my projects are 100% java): Project-A bin lib src RootLevelPackageClass.java I'm not currently using Maven but am wondering if this is a Maven convention or not or if there is another reason. Can someone explain why the first version is so popular these days and if I should adopt this new convention or not? Chris

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  • How sophisticated should be DAL?

    - by Andrew Florko
    Basically, DAL (Data Access Layer) should provide simple CRUD (Create/Read/Update/Delete) methods but I always have a temptation to create more sophisticated methods in order to minimize database access roundtrips from Business Logic Layer. What do you think about following extensions to CRUD (most of them are OK I suppose): Read: GetById, GetByName, GetPaged, GetByFilter... e.t.c. methods Create: GetOrCreate methods (model entity is returned from DB or created if not found and returned), Create(lots-of-relations) instead of Create and multiple AssignTo methods calls Update: Merge methods (entities list are updated, created and deleted in one call) Delete: Delete(bool children) - optional children delete, Cleanup methods Where do you usually implement Entity Cache capabilities? DAL or BLL? (My choice is BLL, but I have seen DAL implementations also) Where is the boundary when you decide: this operation is too specific so I should implement it in Business Logic Layer as DAL multiple calls? I often found insufficient BLL operations that were implemented in dozen database roundtrips because developer was afraid to create a bit more sophisticated DAL. Thank you in advance!

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  • Use continue or Checked Exceptions when checking and processing objects

    - by Johan Pelgrim
    I'm processing, let's say a list of "Document" objects. Before I record the processing of the document successful I first want to check a couple of things. Let's say, the file referring to the document should be present and something in the document should be present. Just two simple checks for the example but think about 8 more checks before I have successfully processed my document. What would have your preference? for (Document document : List<Document> documents) { if (!fileIsPresent(document)) { doSomethingWithThisResult("File is not present"); continue; } if (!isSomethingInTheDocumentPresent(document)) { doSomethingWithThisResult("Something is not in the document"); continue; } doSomethingWithTheSucces(); } Or for (Document document : List<Document> documents) { try { fileIsPresent(document); isSomethingInTheDocumentPresent(document); doSomethingWithTheSucces(); } catch (ProcessingException e) { doSomethingWithTheExceptionalCase(e.getMessage()); } } public boolean fileIsPresent(Document document) throws ProcessingException { ... throw new ProcessingException("File is not present"); } public boolean isSomethingInTheDocumentPresent(Document document) throws ProcessingException { ... throw new ProcessingException("Something is not in the document"); } What is more readable. What is best? Is there even a better approach of doing this (maybe using a design pattern of some sort)? As far as readability goes my preference currently is the Exception variant... What is yours?

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  • Returning true or error message in Ruby

    - by seaneshbaugh
    I'm wondering if writing functions like this is considered good or bad form. def test(x) if x == 1 return true else return "Error: x is not equal to one." end end And then to use it we do something like this: result = test(1) if result != true puts result end result = test(2) if result != true puts result end Which just displays the error message for the second call to test. I'm considering doing this because in a rails project I'm working on inside my controller code I make calls to a model's instance methods and if something goes wrong I want the model to return the error message to the controller and the controller takes that error message and puts it in the flash and redirects. Kinda like this def create @item = Item.new(params[:item]) if [email protected]? result = @item.save_image(params[:attachment][:file]) if result != true flash[:notice] = result redirect_to(new_item_url) and return end #and so on... That way I'm not constructing the error messages in the controller, merely passing them along, because I really don't want the controller to be concerned with what the save_image method itself does just whether or not it worked. It makes sense to me, but I'm curious as to whether or not this is considered a good or bad way of writing methods. Keep in mind I'm asking this in the most general sense pertaining mostly to ruby, it just happens that I'm doing this in a rails project, the actual logic of the controller really isn't my concern.

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  • Generic data input form in asp.net mvc application

    - by Diego
    Hello, I have an application that have EF 16 classes that share this information: They all are classes only with a key field and a description. I think it should be a waste if I make a controller with just 1 method just to present a form to fill these classes info, then I was thinking in to make a generic form(with key, description) and dynamically fill the right class through a sort of selection the selected info in any way, any good suggestion or pattern to do that? Where the generic methods should be located.

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  • index 'enabled' fields good idea?

    - by sibidiba
    Content of a website is stored in a MySQL database. 99% of the content will be enabled, but some (users, posts etc.) will be disabled. Most of the queries end as WHERE (...) AND enabled Is it a good idea to create an index on the field 'enabled'?

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  • IEnumerable and IEnumerator in the same class, bad idea?

    - by David Rutten
    Is this a bad idea? Private Class GH_DataStructureEnumerator(Of Q As Types.IGH_Goo) Implements IEnumerable(Of Q) Implements IEnumerator(Of Q) .... .... 'Current, MoveNext, Reset etc.' .... .... Public Function GetEnumerator_Generic() As IEnumerator(Of Q) _ Implements IEnumerable(Of Q).GetEnumerator Return Me End Function End Class This class is only visible as an IEnumerable(Of T) readonly property, and it saves me an additional class that wraps IEnumerator(Of T). But somehow it just seems wrong. Is there a better way?

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  • PHP Database connection practice

    - by Phill Pafford
    I have a script that connects to multiple databases (Oracle, MySQL and MSSQL), each database connection might not be used each time the script runs but all could be used in a single script execution. My question is, "Is it better to connect to all the databases once in the beginning of the script even though all the connections might not be used. Or is it better to connect to them as needed, the only catch is that I would need to have the connection call in a loop (so the database connection would be new for X amount of times in the loop). Yeah Example Code #1: // Connections at the beginning of the script $dbh_oracle = connect2db(); $dbh_mysql = connect2db(); $dbh_mssql = connect2db(); for ($i=1; $i<=5; $i++) { // NOTE: might not use all the connections $rs = queryDb($query,$dbh_*); // $dbh can be any of the 3 connections } Yeah Example Code #2: // Connections in the loop for ($i=1; $i<=5; $i++) { // NOTE: Would use all the connections but connecting multiple times $dbh_oracle = connect2db(); $dbh_mysql = connect2db(); $dbh_mssql = connect2db(); $rs_oracle = queryDb($query,$dbh_oracle); $rs_mysql = queryDb($query,$dbh_mysql); $rs_mssql = queryDb($query,$dbh_mssql); } now I know you could use a persistent connection but would that be one connection open for each database in the loop as well? Like mysql_pconnect(), mssql_pconnect() and adodb for Oracle persistent connection method. I know that persistent connection can also be resource hogs and as I'm looking for best performance/practice.

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  • What is the most elegant way to validate the presence of ONLY one out of two attributes using Rails?

    - by marcgg
    class Followup < ActiveRecord::Base belongs_to :post belongs_to :comment end This model needs to only have either a post or a comment, but only one of the two. Here's the rspec for what I'm trying to do: it "should be impossible to have both a comment and a post" do followup = Followup.make followup.comment = Comment.make followup.should be_valid followup.post = Post.make followup.should_not be_valid end I can see a bunch of ways of doing this, but what would be the most elegant way of doing this?

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  • Why Shouldn't I Programmatically Submit Username/Password to Facebook/Twitter/Amazon/etc?

    - by viatropos
    I wish there was a central, fully customizable, open source, universal login system that allowed you to login and manage all of your online accounts (maybe there is?)... I just found RPXNow today after starting to build a Sinatra app to login to Google, Facebook, Twitter, Amazon, OpenID, and EventBrite, and it looks like it might save some time. But I keep wondering, not being an authentication guru, why couldn't I just have a sleek login page saying "Enter username and password, and check your login service", and then in the background either scrape the login page from say EventBrite and programmatically submit the form with Mechanize, or use an API if there was one? It would be so much cleaner and such a better user experience if they didn't have to go through popups and redirects and they could use any previously existing accounts. My question is: What are the reasons why I shouldn't do something like that? I don't know much about the serious details of cookies/sessions/security, so if you could be descriptive or point me to some helpful links that would be awesome. Thanks!

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  • Time/resource allocation on a Stylish vs. Functional user interface

    - by jasonk
    When developing applications how much focus/time do you place on an application’s style vs. functionality. Battleship gray apps drive me insane. On the other hand maximizing a business application’s "style" can tax time and financial resources. Applications need to be appealing to resell or meet basic customer expectations, but defining a healthy medium can be difficult. What would you say are reasonable "standards" for allocating develop time/resources should be dedicated to stylizing a business application?

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  • Where do you keep your code?

    - by skiphoppy
    Your code is of course checked into a repository somewhere, but where do you keep your working copy/copies? C:\Program Files isn't right, as it's for installed packages. My Documents somehow doesn't seem right, either—a My Code folder next to My Music and My Pictures? Dumping in C:\ is messy, but seems to be "working" for other people in my office.

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  • Turning Floats into Their Closest (UTF-8 Character) Fraction.

    - by Mark Tomlin
    I want to take any real number, and return the closest number, with the closest fraction as available in the UTF-8 character set, appropriate. 0/4 = 0.00 = # < .125 1/4 = 0.25 = ¼ # > .125 & < .375 2/4 = 0.50 = ½ # > .375 & < .625 3/4 = 0.75 = ¾ # > .625 & < .875 4/4 = 1.00 = # > .875 I made this function to do that task: function displayFraction($realNumber) { if (!is_float($realNumber)) { return $realNumber; } list($number, $decimal) = explode('.', $realNumber); $decimal = '.' . $decimal; switch($decimal) { case $decimal < 0.125: return $number; case $decimal > 0.125 && $decimal < 0.375: return $number . '¼'; # 188 ¼ &#188; case $decimal > 0.375 && $decimal < 0.625: return $number . '½'; # 189 ½ &#189; case $decimal > 0.625 && $decimal < 0.875: return $number . '¾'; # 190 ¾ &#190; case $decimal < 0.875: return ++$number; } } What are the better / diffrent way to do this? echo displayFraction(3.1) . PHP_EOL; # Outputs: 3 echo displayFraction(3.141593) . PHP_EOL; # Outputs: 3¼ echo displayFraction(3.267432) . PHP_EOL; # Outputs: 3¼ echo displayFraction(3.38) . PHP_EOL; # Outputs: 3½ Expand my mind!

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  • Using the using statement with WinForms... Good Practice?

    - by Nate Heinrich
    I understand the concept and reasons behind using the using statement, and I use it with things like file resources and remote connections, I was wondering if it is good practice to use the using statement with WinForm forms and dialogs? using (MyDialog dlg = new MyDialog()) { if (dlg.ShowDialog() == EDialogResult.OK) { // Do Something } } Thanks!

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  • Checking for empty arrays: count vs empty

    - by Dan McG
    This question on 'How to tell if a PHP array is empty' had me thinking of this question Is there a reason that count should be used instead of empty when determining if an array is empty or not? My personal thought would be if the 2 are equivalent for the case of empty arrays you should use empty because it gives a boolean answer to a boolean question. From the question linked above, it seems that count($var) == 0 is the popular method. To me, while technically correct, makes no sense. E.g. Q: $var, are you empty? A: 7. Hmmm... Is there a reason I should use count == 0 instead or just a matter of personal taste? As pointed out by others in comments for a now deleted answer, count will have performance impacts for large arrays because it will have to count all elements, whereas empty can stop as soon as it knows it isn't empty. So, if they give the same results in this case, but count is potentially inefficient, why would we ever use count($var) == 0?

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  • What is the best practice for adding persistence to an MVC model?

    - by etheros
    I'm in the process of implementing an ultra-light MVC framework in PHP. It seems to be a common opinion that the loading of data from a database, file etc. should be independent of the Model, and I agree. What I'm unsure of is the best way to link this "data layer" into MVC. Datastore interacts with Model //controller public function update() { $model = $this->loadModel('foo'); $data = $this->loadDataStore('foo', $model); $data->loadBar(9); //loads data and populates Model $model->setBar('bar'); $data->save(); //reads data from Model and saves } Controller mediates between Model and Datastore Seems a bit verbose and requires the model to know that a datastore exists. //controller public function update() { $model = $this->loadModel('foo'); $data = $this->loadDataStore('foo'); $model->setDataStore($data); $model->getDataStore->loadBar(9); //loads data and populates Model $model->setBar('bar'); $model->getDataStore->save(); //reads data from Model and saves } Datastore extends Model What happens if we want to save a Model extending a database datastore to a flatfile datastore? //controller public function update() { $model = $this->loadHybrid('foo'); //get_class == Datastore_Database $model->loadBar(9); //loads data and populates $model->setBar('bar'); $model->save(); //saves } Model extends datastore This allows for Model portability, but it seems wrong to extend like this. Further, the datastore cannot make use of any of the Model's methods. //controller extends model public function update() { $model = $this->loadHybrid('foo'); //get_class == Model $model->loadBar(9); //loads data and populates $model->setBar('bar'); $model->save(); //saves } EDIT: Model communicates with DAO //model public function __construct($dao) { $this->dao = $dao; } //model public function setBar($bar) { //a bunch of business logic goes here $this->dao->setBar($bar); } //controller public function update() { $model = $this->loadModel('foo'); $model->setBar('baz'); $model->save(); } Any input on the "best" option - or alternative - is most appreciated.

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  • Avoid writing SQL queries altogether in SSIS

    - by Jonn
    Working on a Data Warehouse project, the guy that gave us the tutorial advised that we stick to using SQL queries over defining a lot of data flow transformations, citing points like it'll consume a lot of memory on the ETL box so we'd rather leave the processing to the DB box. Is this really advisable? Where's the balance between relying on GUI tools over executing a bunch of SQL scripts on your Integration package? And honestly, I'd like to avoid writing SQL queries as much as I can.

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  • How often to run getWritableDatabase() and getReadableDatabase()?

    - by jawonlee
    I'm writing a Service, a Content Provider, and one or more apps. The Service writes new data to the Content Provider's SQLite database every 5 minutes or so plus at user input, and is intended to run pretty much forever in the background. The app, when running, will display data pulled from the Content Provider, and will be refreshed whenever the Service puts more data into the Content Provider's database. Given that the Service only inserts into the database once every five minutes, when is the right time to call SQLiteOpenHelper's getWritableDatabase() / getReadableDatabase()? Is it on the onCreate() of the Content Provider, or should I run it every time there is an insert() and close it at the end of insert()? The data being inserted every 5 minutes will contain multiple inserts.

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  • Should image size be defined in the img tag height/width attributes or in CSS?

    - by Benjamin Manns
    Is it better coding practice to define an images size in the img tag's width and height attributes? <img src="images/academia_vs_business.png" width="740" height="382" alt="" /> Or in the CSS style with width/height? <img src="images/academia_vs_business.png" style="width:740px; height:382px;" alt="" /> Or both? <img src="images/academia_vs_business.png" width="740" height="382" style="width:740px; height:382px" alt="" />

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  • Constructor versus setter injection

    - by Chris
    Hi, I'm currently designing an API where I wish to allow configuration via a variety of methods. One method is via an XML configuration schema and another method is through an API that I wish to play nicely with Spring. My XML schema parsing code was previously hidden and therefore the only concern was for it to work but now I wish to build a public API and I'm quite concerned about best-practice. It seems that many favor javabean type PoJo's with default zero parameter constructors and then setter injection. The problem I am trying to tackle is that some setter methods implementations are dependent on other setter methods being called before them in sequence. I could write anal setters that will tolerate themselves being called in many orders but that will not solve the problem of a user forgetting to set the appropriate setter and therefore the bean being in an incomplete state. The only solution I can think of is to forget about the objects being 'beans' and enforce the required parameters via constructor injection. An example of this is in the default setting of the id of a component based on the id of the parent components. My Interface public interface IMyIdentityInterface { public String getId(); /* A null value should create a unique meaningful default */ public void setId(String id); public IMyIdentityInterface getParent(); public void setParent(IMyIdentityInterface parent); } Base Implementation of interface: public abstract class MyIdentityBaseClass implements IMyIdentityInterface { private String _id; private IMyIdentityInterface _parent; public MyIdentityBaseClass () {} @Override public String getId() { return _id; } /** * If the id is null, then use the id of the parent component * appended with a lower-cased simple name of the current impl * class along with a counter suffix to enforce uniqueness */ @Override public void setId(String id) { if (id == null) { IMyIdentityInterface parent = getParent(); if (parent == null) { // this may be the top level component or it may be that // the user called setId() before setParent(..) } else { _id = Helpers.makeIdFromParent(parent,getClass()); } } else { _id = id; } } @Override public IMyIdentityInterface getParent() { return _parent; } @Override public void setParent(IMyIdentityInterface parent) { _parent = parent; } } Every component in the framework will have a parent except for the top level component. Using the setter type of injection, then the setters will have different behavior based on the order of the calling of the setters. In this case, would you agree, that a constructor taking a reference to the parent is better and dropping the parent setter method from the interface entirely? Is it considered bad practice if I wish to be able to configure these components using an IoC container? Chris

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