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• C# Configuration Manager . ConnectionStrings

  - by Yoda

  I have a console app containing an application configuration file containing one connection string as shown below: <configuration> <connectionStrings> <add name="Target" connectionString="server=MYSERVER; Database=MYDB; Integrated Security=SSPI;" /> </connectionStrings> </configuration> When I pass this to my Connection using: ConfigurationManager.ConnectionStrings[1].ToString() I have two values in there, hence using the second in the collection, my question is where is this second coming from? I have checked the Bin version and original and its not mine! Its obviously a system generated one but I have not seen this before? Can anyone enlighten me? The mystery connection string is: data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true This isn't a problem as such I would just like to know why this is occuring? Thanks in advance! For future reference to those who may or may not stumble on this, after discovering the machine.config its become apparent it is bad practice to refer to a config by its index as each stack will potentially be different, which is why "Keys" are used. Cheers all!

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• Agile language for 2d game prototypes?

  - by instanceofTom

  Occasionally ( read: when my fiancé allows ) I like to prototype different game or game-like ideas I have. Usually I use Java or C# (not xna yet) because they are the languages I have the most practice with. However I would like to learn something more suited to agile development; a language in which it would be easier to knock out quick prototypes. At my job I have recently been working with looser (weak/dynamically typed) languages, specifically python and groovy, and I think something similar would fit what I am looking for. So, my question is: What languages (and framework/engine) would be good for rapidly developing prototypes of 2d game concepts? A few notes: I don't need blazing fast bitcrunching performance. In this case I would strongly prefer ease of development over performance. I'd like to use a language with a healthy community, which to me means a fair amount of maintained 3rd party, libraries. I'd like the language to be cross-platform friendly, I work on a variety of different operating systems and would like something that is portable with minimum effort. I can't imagine myself using a language with out decent options for debugging and editor syntax highlighting support. Note: If you are aware of a Java or C# library/framework that you think streamlines producing game prototypes I open to learning something new for those languages too

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• too much recursion in javascript with jquery mouseover

  - by Stacia

  I am a JS novice. Using some code I found here to help me with mouseover scale/rotate images but now when I try to apply it to more than one object I'm getting errors saying "too much recursion". Before the function didn't take any arguments, it just was on s_1 and it worked fine. I am tempted to just write different code for each object but that isn't very good programming practice. var over = false; $(function(){ $("#s_1").hover(function(){ over = true; swing_left_anim("#s_1"); }, function(){ over = false; }); $("#np_1").hover(function(){ over = true; swing_left_anim("np_1"); }, function(){ over = false; }); }); function swing_left_anim(obj){ $(obj).animate({ rotate: '0deg' }, { duration: 500 }); if (over) { $(obj).animate({ rotate: '25deg' }, 500, swing_right_anim(obj)); } } function swing_right_anim(obj){ $(obj).animate({ rotate: '-25deg' }, 500, swing_left_anim(obj)); }

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• Choosing between instance methods and separate functions?

  - by StackedCrooked

  Adding functionality to a class can be done by adding a method or by defining a function that takes an object as its first parameter. Most programmers that I know would choose for the solution of adding a instance method. However, I sometimes prefer to create a separate function. For example, in the example code below Area and Diagonal are defined as separate functions instead of methods. I find it better this way because I think these functions provide enhancements rather than core functionality. Is this considered a good/bad practice? If the answer is "it depends", then what are the rules for deciding between adding method or defining a separate function? class Rect { public: Rect(int x, int y, int w, int h) : mX(x), mY(y), mWidth(w), mHeight(h) { } int x() const { return mX; } int y() const { return mY; } int width() const { return mWidth; } int height() const { return mHeight; } private: int mX, mY, mWidth, mHeight; }; int Area(const Rect & inRect) { return inRect.width() * inRect.height(); } float Diagonal(const Rect & inRect) { return std::sqrt(std::pow(static_cast<float>(inRect.width()), 2) + std::pow(static_cast<float>(inRect.height()), 2)); }

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• Should a setter return immediately if assigned the same value?

  - by Andrei Rinea

  In classes that implement INotifyPropertyChanged I often see this pattern : public string FirstName { get { return _customer.FirstName; } set { if (value == _customer.FirstName) return; _customer.FirstName = value; base.OnPropertyChanged("FirstName"); } } Precisely the lines if (value == _customer.FirstName) return; are bothering me. I've often did this but I am not that sure it's needed nor good. After all if a caller assigns the very same value I don't want to reassign the field and, especially, notify my subscribers that the property has changed when, semantically it didn't. Except saving some CPU/RAM/etc by freeing the UI from updating something that will probably look the same on the screen/whatever_medium what do we obtain? Could some people force a refresh by reassigning the same value on a property (NOT THAT THIS WOULD BE A GOOD PRACTICE HOWEVER)? 1. Should we do it or shouldn't we? 2. Why?

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• Passing arguments and values from HTML to jQuery (events)

  - by Jaroslav Moravec

  What is the practice to pass arguments from HTML to jQuery events function. For example getting id of row from db: <tr class="jq_killMe" id="thisItemId-id"> ... </tr> and jQuery: $(".jq_killMe").click(function () { var tmp = $(this).attr('id).split("-"); var id = tmp[0] // ... } What's the best practise, if I want to pass more than one argument? Is it better not to use jQuery? For example: <tr onclick="killMe('id')"> ... </tr> I didn't find the answer on my question, I will be glad even for links. Thanks. Edit (pre solution) So you suggested two methods to do that: Add custom attributes to element (XHTML) Use attribute ID and parse it by regex Attribute data-* attributes in HTML5 Use hidden children elements I like first solution, but... I would like to (I have to (employer)) produce valid code. Here is a nice question and answers: http://stackoverflow.com/questions/994856/so-what-if-custom-html-attributes-arent-valid-xhtml And the second is not so pretty as the first, but valid. So the compromise is... The third is the solution for future, but here is a lot of CMS where we have to use XHTML or HTML4. (And HTML5 is the long process)

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• Prevent two users from editing the same data

  - by Industrial

  Hi everyone, I have seen a feature in different web applications including Wordpress (not sure?) that warns a user if he/she opens an article/post/page/whatever from the database, while someone else is editing the same data simultaneously. I would like to implement the same feature in my own application and I have given this a bit of thought. Is the following example a good practice on how to do this? It goes a little something like this: 1) User A enters a the editing page for the mysterious article X. The database tableEvents is queried to make sure that no one else is editing the same page for the moment, which no one is by then. A token is then randomly being generated and is inserted into a database table called Events. 1) User B also want's to make updates to the article X. Now since our User A already is editing the article, the Events table is queried and looks like this: | timestamp | owner | Origin | token | ------------------------------------------------------------ | 1273226321 | User A | article-x | uniqueid## | 2) The timestamp is being checked. If it's valid and less than say 100 seconds old, a message appears and the user cannot make any changes to the requested article X: Warning: User A is currently working with this article. In the meantime, editing cannot be done. Please do something else with your life. 3) If User A decides to go on and save his changes, the token is posted along with all other data to update the database, and toggles a query to delete the row with token uniqueid##. If he decides to do something else instead of committing his changes, the article X will still be available for editing in 100 seconds for User B Let me know what you think about this approach! Wish everyone a great weekend!

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• correct format for function prototype

  - by yCalleecharan

  Hi, I'm writing to a text file using the following declaration: void create_out_file(char file_name[],long double *z1){ FILE *out; int i; if((out = fopen(file_name, "w+")) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < ARRAY_SIZE; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } Where z1 is an long double array of length ARRAY_SIZE. The calling function is: create_out_file("E:/first67/jz1.txt", z1); I defined the prototype as: void create_out_file(char file_name[], long double z1[]); which I'm putting before "int main" but after the preprocessor directives. My code works fine. I was thinking of putting the prototype as void create_out_file(char file_name[],long double *z1). Is this correct? *z1 will point to the first array element of z1. Is my declaration and prototype good programming practice? Thanks a lot...

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• Which version of Grady Booch's OOA/D book should I buy?

  - by jackj

  Grady Booch's "Object-Oriented Analysis and Design with Applications" is available brand new in both the 2nd edition (1993) and the 3rd edition (2007), while many used copies of both editions are available. Here are my concerns: 1) The 2nd edition uses C++: given that I just finished reading my first two C++ books (Accelerated C++ and C++ Primer) I guess practical tips can only help, so the 2nd edition is probably best (I think the 3rd edition has absolutely no code). On the other hand, the C++ books I read insist on the importance of using standard C++, whereas Booch's 2nd edition was published before the 1998 standard. 2) The 2nd edition is shorter (608 pages vs. 720) so, I guess, it will be slightly easier to get through. 3) The 3rd edition uses UML 2.0, whereas the 2nd edition is pre-UML. Some reviews say that the notation in the 2nd edition is close enough to UML, so it doesn't matter, but I don't know if I should be worrying about this or not. 4) The 2nd edition is available in good-shape used copies for considerably less than what the 3rd one goes for. Given all the above factors, do you think I should buy the 2nd or the 3rd edition? Recommendations on other books are also welcome but I would prefer it if whoever answers has read at least one of the versions of Booch's book (preferably both!). I have already bought but not read GoF and Riel's books. I also know that I should practice a lot with real-life code. Thanks.

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• Formvalidator from the iframe.

  - by basit74

  Hello I have a following formvalidatior function in my document. function formValidator(formid) { var form = cic.$(formid); if(!form) return (''); var errors = []; var len = form.elements.length; for(var elementIdx = 0; elementIdx < len; elementIdx++) { var element = form.elements[elementIdx]; if(!element && !element.getAttribute('validationtype')) return (''); switch (element.getAttribute('validationtype')) { case 'text' : if(cic.getValue(element).strip() == "") errors.push(element.getAttribute('validationmsg')); break; case 'email' : if(!cic.isEmail(cic.getValue(element))) errors.push(element.getAttribute('validationmsg')); break; case 'numeric' : if(isNaN(cic.getValue(element).replace(',', '.'))) errors.push(element.getAttribute('validationmsg')); break; case 'confirm' : if(cic.getValue(cic.$(element.getAttribute('sourcefield'))) !== cic.getValue(element)) errors.push(element.getAttribute('validationmsg')); break; } } return (errors.length > 0) ? '<li>' + errors.uniq().join("<li>") : ''; } It works fine, now I have an Iframe in my document, and that I frame contains the form to validate. What will be the best practice to change this function in such a way that it can validate document forms and iframe from simeltaniously. Thanks

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• Implementing list position locator in C++?

  - by jfrazier

  I am writing a basic Graph API in C++ (I know libraries already exist, but I am doing it for the practice/experience). The structure is basically that of an adjacency list representation. So there are Vertex objects and Edge objects, and the Graph class contains: list<Vertex *> vertexList list<Edge *> edgeList Each Edge object has two Vertex* members representing its endpoints, and each Vertex object has a list of Edge* members representing the edges incident to the Vertex. All this is quite standard, but here is my problem. I want to be able to implement deletion of Edges and Vertices in constant time, so for example each Vertex object should have a Locator member that points to the position of its Vertex* in the vertexList. The way I first implemented this was by saving a list::iterator, as follows: vertexList.push_back(v); v->locator = --vertexList.end(); Then if I need to delete this vertex later, then rather than searching the whole vertexList for its pointer, I can call: vertexList.erase(v->locator); This works fine at first, but it seems that if enough changes (deletions) are made to the list, the iterators will become out-of-date and I get all sorts of iterator errors at runtime. This seems strange for a linked list, because it doesn't seem like you should ever need to re-allocate the remaining members of the list after deletions, but maybe the STL does this to optimize by keeping memory somewhat contiguous? In any case, I would appreciate it if anyone has any insight as to why this happens. Is there a standard way in C++ to implement a locator that will keep track of an element's position in a list without becoming obsolete? Much thanks, Jeff

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• writing CMS in ZEND

  - by Neoman

  Hello guys, I'm trying to write my own CMS using Zend framework and I created modular structure. I have modules like 'news', 'blog' and etc. Also I have "admin" module which has different layout and this is like the administrator panel where admin can edit all the content and etc. But the problem is that I'm looking for the best practice and solution to solve the problem. I don't like the idea that my admin module will have a lot of controllers which will be for administer all the other modules. So I want to ask you all, maybe you have some tuts or just have an advice how to implement admin module separated from other modules as much as it can be done. Because I just want to copy one module for example from one project to another and I want it will work same. I don't want to search the right admin controller, view or something like this in admin module and copy this part seperatelly into new admin module. Hope the question and situation is clear enough and I will be happy to hear any advice or see any tutorials how to do it. Thanks guys!

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• ObjC internals. Why my duck typing attempt failed?

  - by Piotr Czapla

  I've tried to use id to create duck typing in objective-c. The concept looks fine in theory but failed in practice. I was unable to use any parameters in my methods. The methods were called but parameters were wrong. I was getting BAD_ACESS for objects and random values for primitives. I've attached a simple example below. The question: Does any one knows why the methods parameters are wrong? What is happening under the hood of the objective-c? Note: I'm interest in the details. I know how to make the example below work. An example: I've created a simple class Test that is passed to an other class using property id test. @implementation Test - (void) aSampleMethodWithFloat:(float) f andInt: (int) i { NSLog(@"Parameters: %f, %i\n", f, i); } @end Then in the class the following loop is executed: for (float f=0.0f; f < 100.0f ; f += 0.3f) { [self.test aSampleMethodWithOneFloatParameter: f]; // warning: no method found. } Here is the output that I'm getting. As you can see the method was called but the parameters were wrong. Parameters: 0.000000, 0 Parameters: -0.000000, 1069128089 Parameters: -0.000000, 1070176665 Parameters: 2.000000, 1070805811 Parameters: -0.000000, 1071225241 Parameters: 0.000000, 1071644672 Parameters: 2.000000, 1071854387 Parameters: 36893488147419103232.000000, 1072064102 Parameters: -0.000000, 1072273817 Parameters: -36893488147419103232.000000, 1072483532

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• Jquery and Ajax Post issue

  - by Jerry

  Hello guys I am trying to add a click event on the element that is return from the server via ajax. Apparently, I have to attached my js file inside my return response instead of my main script. Is this the best practice? Do I have to create the separated js file to add event on the return text?? Example: My Jquery - selectWeek.js $(document).ready(function(){ //handle ajax.. var url="sendSchedule.php"; $.post( url, {week:input}, function(responseText){ $("#ajax").html(responseText); }, "html" ); // click on #add button $("#add").click(function(){ //do something return false; }); }); My main page <script type="text/javascript" src="JS/selectWeek.js"></script> </HEAD> <BODY> //the code that trigger ajax is omitted <div id=ajax> //the response text will be inserted here </div> </BODY> </HTML> response from the server // display html (omit) // Do I have to attach the same js file to let #add listen the event? <script type="text/javascript" src="JS/selectWeek.js"></script> <form> <input type='button' id='add' value='add'/> </form> I am not sure if i make my question clear. I want to know if I need to add events on the return text. Do I have to add js file link on the return text or there is a way to do it on the main page. Thanks for any reply.

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• How to not use JavaScript with in the elements events attributes but still load via AJAX

  - by thecoshman

  I am currently loading HTMl content via AJAX. I have code for things on different elements onclick attributes (and other event attributes). It does work, but I am starting to find that the code is getting rather large, and hard to read. I have also read that it is considered bad practice to have the event code 'inline' like this and that I should really do by element.onclick = foobar and have foobar defined somewhere else. I understand how with a static page it is fairly easy to do this, just have a script tag at the bottom of the page and once the page is loaded have it executed. This can then attach any and all events as you need them. But how can I get this sort of affect when loading content via AJAX. There is also the slight case that the content loaded can very depending on what is in the database, some times certain sections of HTML, such as tables of results, will not even be displayed there will be something else entirely. I can post some samples of code if any body needs them, but I have no idea what sort of things would help people with this one. I will point out, that I am using Jquery already so if it has some helpful little functions that would be rather sweet¬

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• Macro to improve callback registration readability

  - by Warren Seine

  I'm trying to write a macro to make a specific usage of callbacks in C++ easier. All my callbacks are member functions and will take this as first argument and a second one whose type inherits from a common base class. The usual way to go is: register_callback(boost::bind(&my_class::member_function, this, _1)); I'd love to write: register_callback(HANDLER(member_function)); Note that it will always be used within the same class. Even if typeof is considered as a bad practice, it sounds like a pretty solution to the lack of __class__ macro to get the current class name. The following code works: typedef typeof(*this) CLASS; boost::bind(& CLASS :: member_function, this, _1)(my_argument); but I can't use this code in a macro which will be given as argument to register_callback. I've tried: #define HANDLER(FUN) \ boost::bind(& typeof(*this) :: member_function, this, _1); which doesn't work for reasons I don't understand. Quoting GCC documentation: A typeof-construct can be used anywhere a typedef name could be used. My compiler is GCC 4.4, and even if I'd prefer something standard, GCC-specific solutions are accepted.

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• What is wrong with locking non-static fields? What is the correct way to lock a particular instance?

  - by smartcaveman

  Why is it considered bad practice to lock non-static fields? And, if I am not locking non-static fields, then how do I lock an instance method without locking the method on all other instances of the same or derived class? I wrote an example to make my question more clear. public abstract class BaseClass { private readonly object NonStaticLockObject = new object(); private static readonly object StaticLockObject = new object(); protected void DoThreadSafeAction<T>(Action<T> action) where T: BaseClass { var derived = this as T; if(derived == null) { throw new Exception(); } lock(NonStaticLockObject) { action(derived); } } } public class DerivedClass :BaseClass { private readonly Queue<object> _queue; public void Enqueue(object obj) { DoThreadSafeAction<DerivedClass>(x=>x._queue.Enqueue(obj)); } } If I make the lock on the StaticLockObject, then the DoThreadSafeAction method will be locked for all instances of all classes that derive from BaseClass and that is not what I want. I want to make sure that no other threads can call a method on a particular instance of an object while it is locked.

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• C++: is it safe to work with std::vectors as if they were arrays?

  - by peoro

  I need to have a fixed-size array of elements and to call on them functions that require to know about how they're placed in memory, in particular: functions like glVertexPointer, that needs to know where the vertices are, how distant they are one from the other and so on. In my case vertices would be members of the elements to store. to get the index of an element within this array, I'd prefer to avoid having an index field within my elements, but would rather play with pointers arithmetic (ie: index of Element *x will be x - & array[0]) -- btw, this sounds dirty to me: is it good practice or should I do something else? Is it safe to use std::vector for this? Something makes me think that an std::array would be more appropriate but: Constructor and destructor for my structure will be rarely called: I don't mind about such overhead. I'm going to set the std::vector capacity to size I need (the size that would use for an std::array, thus won't take any overhead due to sporadic reallocation. I don't mind a little space overhead for std::vector's internal structure. I could use the ability to resize the vector (or better: to have a size chosen during setup), and I think there's no way to do this with std::array, since its size is a template parameter (that's too bad: I could do that even with an old C-like array, just dynamically allocating it on the heap). If std::vector is fine for my purpose I'd like to know into details if it will have some runtime overhead with respect to std::array (or to a plain C array): I know that it'll call the default constructor for any element once I increase its size (but I guess this won't cost anything if my data has got an empty default constructor?), same for destructor. Anything else?

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• What are the differences between mapping,binding and parsing?

  - by sfrj

  I am starting to learn web-services in java EE6. I did web development before, but never nothing related to web services. All is new to me and the books and the tutorials i find in the web are to technical. I started learning about .xsd schemas and also .xml. In that topic i feel confident, i understand what are the schemas used for and what validation means. Now my next step is learning about JAX-B(Java Api for XML Binding). I rode some about it and i did also some practice in my IDE. But i have lots of basic doubts, that make me stuck and cannot feel confident to continue to the next topic. Ill appreciate a lot if someone could explain me well my doubts: What does it mean mapping and what is a mapping tool? What does it mean binding and what is a binding tool? What does it mean parsing and what is a parsing tool? How is JAX-B related to mapping,binding and parsing? I am seeking for a good answer built by you, not just a copy paste from google(Ive already been online a few hours and only got confused).

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• Pattern for UI configuration

  - by TERACytE

  I have a Win32 C++ program that validates user input and updates the UI with status information and options. Currently it is written like this: void ShowError() { SetIcon(kError); SetMessageString("There was an error"); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } void ShowSuccess() { SetIcon(kError); std::String statusText (GetStatusText()); SetMessageString(statusText); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } // plus several more methods to update the UI using similar mechanisms I do not likes this because it duplicates code and causes me to update several methods if something changes in the UI. I am wondering if there is a design pattern or best practice to remove the duplication and make the functionality easier to understand and update. I could consolidate the code inside a config function and pass in flags to enable/disable UI items, but I am not convinced this is the best approach. Any suggestions and ideas?

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• How should I secure my webapp written using Wicket, Spring, and JPA?

  - by Martin

  So, I have an web-based application that is using the Wicket 1.4 framework, and it uses Spring beans, the Java Persistence API (JPA), and the OpenSessionInView pattern. I'm hoping to find a security model that is declarative, but doesn't require gobs of XML configuration -- I'd prefer annotations. Here are the options so far: Spring Security (guide) - looks complete, but every guide I find that combines it with Wicket still calls it Acegi Security, which makes me think it must be old. Wicket-Auth-Roles (guide 1 and guide 2) - Most guides recommend mixing this with Spring Security, and I love the declarative style of @Authorize("ROLE1","ROLE2",etc). I'm concerned about having to extend AuthenticatedWebApplication, since I'm already extending org.apache.wicket.protocol.http.WebApplication, and Spring is already proxying that behind org.apache.wicket.spring.SpringWebApplicationFactory. SWARM / WASP (guide) - This looks the newest (though the main contributor passed away years ago), but I hate all of the JAAS-styled text files that declare permissions for principals. I also don't like the idea of making an Action class for every single thing a user might want to do. Secure models also aren't immediately obvious to me. Plus, there isn't an Authn example. Additionally, it looks like lots of folks recommend mixing the first and second options. I can't tell what the best practice is at all, though.

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• Is there a standard pattern for scanning a job table executing some actions?

  - by Howiecamp

  (I realize that my title is poor. If after reading the question you have an improvement in mind, please either edit it or tell me and I'll change it.) I have the relatively common scenario of a job table which has 1 row for some thing that needs to be done. For example, it could be a list of emails to be sent. The table looks something like this: ID Completed TimeCompleted anything else... ---- --------- ------------- ---------------- 1 No blabla 2 No blabla 3 Yes 01:04:22 ... I'm looking either for a standard practice/pattern (or code - C#/SQL Server preferred) for periodically "scanning" (I use the term "scanning" very loosely) this table, finding the not-completed items, doing the action and then marking them completed once done successfully. In addition to the basic process for accomplishing the above, I'm considering the following requirements: I'd like some means of "scaling linearly", e.g. running multiple "worker processes" simultaneously or threading or whatever. (Just a specific technical thought - I'm assuming that as a result of this requirement, I need some method of marking an item as "in progress" to avoid attempting the action multiple times.) Each item in the table should only be executed once. Some other thoughts: I'm not particularly concerned with the implementation being done in the database (e.g. in T-SQL or PL/SQL code) vs. some external program code (e.g. a standalone executable or some action triggered by a web page) which is executed against the database Whether the "doing the action" part is done synchronously or asynchronously is not something I'm considering as part of this question.

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• Usage of Assert.Inconclusive

  - by Johannes Rudolph

  Hi, Im wondering how someone should use Assert.Inconclusive(). I'm using it if my Unit test would be about to fail for a reason other than what it is for. E.g. i have a method on a class that calculates the sum of an array of ints. On the same class there is also a method to calculate the average of the element. It is implemented by calling sum and dividing it by the length of the array. Writing a Unit test for Sum() is simple. However, when i write a test for Average() and Sum() fails, Average() is likely to fail also. The failure of Average is not explicit about the reason it failed, it failed for a reason other than what it should test for. That's why i would check if Sum() returns the correct result, otherwise i Assert.Inconclusive(). Is this to be considered good practice? What is Assert.Inconclusive intended for? Or should i rather solve the previous example by means of an Isolation Framework?

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• Checking for nil in view in Ruby on Rails

  - by seaneshbaugh

  I've been working with Rails for a while now and one thing I find myself constantly doing is checking to see if some attribute or object is nil in my view code before I display it. I'm starting to wonder if this is always the best idea. My rationale so far has been that since my application(s) rely on user input unexpected things can occur. If I've learned one thing from programming in general it's that users inputting things the programmer didn't think of is one of the biggest sources of run-time errors. By checking for nil values I'm hoping to sidestep that and have my views gracefully handle the problem. The thing is though I typically for various reasons have similar nil or invalid value checks in either my model or controller code. I wouldn't call it code duplication in the strictest sense, but it just doesn't seem very DRY. If I've already checked for nil objects in my controller is it okay if my view just assumes the object truly isn't nil? For attributes that can be nil that are displayed it makes sense to me to check every time, but for the objects themselves I'm not sure what is the best practice. Here's a simplified, but typical example of what I'm talking about: controller code def show @item = Item.find_by_id(params[:id]) @folders = Folder.find(:all, :order => 'display_order') if @item == nil or @item.folder == nil redirect_to(root_url) and return end end view code <% if @item != nil %> display the item's attributes here <% if @item.folder != nil %> <%= link_to @item.folder.name, folder_path(@item.folder) %> <% end %> <% else %> Oops! Looks like something went horribly wrong! <% end %> Is this a good idea or is it just silly?

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• using dummy row with NOT NULL to solve DEFAULT NULL

  - by Tony38

  I know having DEFAULT NULLS is not a good practice but I have many optional lookup values which are FK in the system so to solve this issue here is what i am doing: I use NOT NULL for every FK / lookup colunms. I have the first row in every lookup table which is PK id = 1 as a dummy row with just "none" in all the columns. This way I can use NOT NULL in my schema and if needed reference to the none row values PK =1 for FKs which do not have any lookup value. Is this a good design or any other work arounds? EDIT: I have: Neighborhood table Postal table. Every neighborhood has a city, so the FK can be NOT NULL. But not every postal code belongs to a neighborhood. Some do, some don't depending on the country. So if i use NOT NULL for the FK between postal and neighborhood then I will be screwed as there has to be some value entered. So what i am doing in essence is: have a row in every table to be a dummy row just to link the FKs. This way row one in neighborhood table will be: n_id = 1 name =none etc... In postal table I can have: postal_code = 3456A3 FK (city) = Moscow FK (neighborhood_id)=1 as a NOT NULL. If I don't have a dummy row in the neighborhood lookup table then I have to declare FK (neighborhood_id) as a Default null column and store blanks in the table. This is an example but there is a huge number of values which will have blanks then in many tables.

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