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  • Array Searching code challenge

    - by RCIX
    Here's my (code golf) challenge: Take two arrays of bytes and determine if the second array is a substring of the first. If it is, output the index at which the contents of the second array appear in the first. If you do not find the second array in the first, then output -1. Example Input: { 63, 101, 245, 215, 0 } { 245, 215 } Expected Output: 2 Example Input 2: { 24, 55, 74, 3, 1 } { 24, 56, 74 } Expected Output 2: -1 Edit: Someone has pointed out that the bool is redundant, so all your function has to do is return an int representing the index of the value or -1 if not found.

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  • Are there any actual case studies on rewrites of software success/failure rates?

    - by James Drinkard
    I've seen multiple posts about rewrites of applications being bad, peoples experiences about it here on Programmers, and an article I've ready by Joel Splosky on the subject, but no hard evidence of case studies. Other than the two examples Joel gave and some other posts here, what do you do with a bad codebase and how do you decide what to do with it based on real studies? For the case in point, there are two clients I know of that both have old legacy code. They keep limping along with it because as one of them found out, a rewrite was a disaster, it was expensive and didn't really work to improve the code much. That customer has some very complicated business logic as the rewriters quickly found out. In both cases, these are mission critical applications that brings in a lot of revenue for the company. The one that attempted the rewrite felt that they would hit a brick wall at some point if the legacy software didn't get upgraded at some point in the future. To me, that kind of risk warrants research and analysis to ensure a successful path. My question is have there been actual case studies that have investigated this? I wouldn't want to attempt a major rewrite without knowing some best practices, pitfalls, and successes based on actual studies. Aftermath: okay, I was wrong, I did find one article: Rewrite or Reuse. They did a study on a Cobol app that was converted to Java.

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  • How can a code editor effectively hint at code nesting level - without using indentation?

    - by pgfearo
    I'm writing an XML text editor that provides 2 view options for the same XML text, one indented (virtually), the other left-justified. The motivation for the left-justified view is to help users 'see' the whitespace characters they're using for indentation of plain-text or XPath code without interference from indentation that is an automated side-effect of the XML context. I want to provide visual clues (in the non-editable part of the editor) for the left-justified mode that will help the user, but without getting too elaborate. I tried just using connecting lines, but that seemed too busy. The best I've come up with so far is shown in a mocked up screenshot of the editor below, but I'm seeking better/simpler alternatives (that don't require too much code). [Edit] Taking the heatmap idea (from: @jimp) I get something like this: or even these alternates:

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  • MUD source code

    - by Tchalvak
    I haven't been able to find a lot of the old, open source mud source codes. I find the way they did things very applicable to text-based/browser based games, and I'd love to be able to skim through parts of 'em for inspiration. For instance, we have this huge list of muds and the relationships between them, but little by way of access to source code. http://en.wikipedia.org/wiki/MUD_trees Often (I'm looking at you, dikumud, http://www.dikumud.com/links.aspx ) the sites of the mud itself doesn't even have a working link to the source. https://github.com/alexmchale/merc-mud has a copy of merc that I found, which certainly contains other works within it's history, but the pickings seems sparse. Does anyone have better resources for gaining access to MUD source code than these?

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  • Maintaining packages with code - Adding a property expression programmatically

    Every now and then I've come across scenarios where I need to update a lot of packages all in the same way. The usual scenario revolves around a group of packages all having been built off the same package template, and something needs to updated to keep up with new requirements, a new logging standard for example.You'd probably start by updating your template package, but then you need to address all your existing packages. Often this can run into the hundreds of packages and clearly that's not a job anyone wants to do by hand. I normally solve the problem by writing a simple console application that looks for files and patches any package it finds, and it is an example of this I'd thought I'd tidy up a bit and publish here. This sample will look at the package and find any top level Execute SQL Tasks, and change the SQL Statement property to use an expression. It is very simplistic working on top level tasks only, so nothing inside a Sequence Container or Loop will be checked but obviously the code could be extended for this if required. The code that actually sets the expression is shown below, the rest is just wrapper code to find the package and to find the task. /// <summary> /// The CreationName of the Tasks to target, e.g. Execute SQL Task /// </summary> private const string TargetTaskCreationName = "Microsoft.SqlServer.Dts.Tasks.ExecuteSQLTask.ExecuteSQLTask, Microsoft.SqlServer.SQLTask, Version=9.0.242.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91"; /// <summary> /// The name of the task property to target. /// </summary> private const string TargetPropertyName = "SqlStatementSource"; /// <summary> /// The property expression to set. /// </summary> private const string ExpressionToSet = "@[User::SQLQueryVariable]"; .... // Check if the task matches our target task type if (taskHost.CreationName == TargetTaskCreationName) { // Check for the target property if (taskHost.Properties.Contains(TargetPropertyName)) { // Get the property, check for an expression and set expression if not found DtsProperty property = taskHost.Properties[TargetPropertyName]; if (string.IsNullOrEmpty(property.GetExpression(taskHost))) { property.SetExpression(taskHost, ExpressionToSet); changeCount++; } } } This is a console application, so to specify which packages you want to target you have three options: Find all packages in the current folder, the default behaviour if no arguments are specified TaskExpressionPatcher.exe .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Find all packages in a specified folder, pass the folder as the argument TaskExpressionPatcher.exe C:\Projects\Alpha\Packages\ .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Find a specific package, pass the file path as the argument TaskExpressionPatcher.exe C:\Projects\Alpha\Packages\Package.dtsx The code was written against SQL Server 2005, but just change the reference to Microsoft.SQLServer.ManagedDTS to be the SQL Server 2008 version and it will work fine. If you get an error Microsoft.SqlServer.Dts.Runtime.DtsRuntimeException: The package failed to load due to error 0xC0011008… then check that the package is from the correct version of SSIS compared to the referenced assemblies, 2005 vs 2008 in other words. Download Sample Project TaskExpressionPatcher.zip (6 KB)

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  • How is technical debt best measured? What metric(s) are most useful?

    - by throp
    If I wanted to help a customer understand the degree of technical debt in his application, what would be the best metric to use? I've stumbled across Erik Doernenburg's code toxicity, and also Sonar's technical debt plugin, but was wondering what others exist. Ideally, I'd like to say "system A has a score of 100 whereas system B has a score of 50, so system A will most likely be more difficult to maintain than system B". Obviously, I understand that boiling down a complex concepts like "technical debt" or "maintainability" into a single number might be misleading or inaccurate (in some cases), however I need a simple way to convey the to a customer (who is not hands-on in the code) roughly how much technical debt is built into their system (relative to other systems), for the goal of building a case for refactoring/unit tests/etc. Again, I'm looking for one single number/graph/visualization, and not a comprehensive list of violations (e.g. CheckStyle, PMD, etc.).

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  • How do programmers deal with Project Lead/Managers?

    - by Simon
    Project Managers/Technical Leads sometimes tend to be over enthusiastic when it comes to software. But during code reviews if instead of functionality of the code the only complain one hears is about formatting/spacing and similar trivial things, when there are far better things to discuss (Among other things I have noticed the sometimes during the so called "reviews" suggestions are made that implementation needs a re-write just because it doesnt use the most happening technology/buzzword) How do fellow programmers deal with such scenarios? or is this just a one off? (or is the fault entirely on me )If you have similar experience and what you did to overcome it? Feel free to share.

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  • The First Annual Crappy Code Games

    - by Testas
    SQLBits announced some super-exciting news! A tie-up with our platinum sponsor, Fusion-io. Together we'll be running a series of events called "The Crappy Code Games" where SQL Server developers will compete to write the worst-performing code and win some very cool prizes including:   •        Gold: A hands-on, high performance flying day for two at Ultimate High plus Fusion-io flight jackets•        Silver: One day racing experience at Palmer Sports where you will drive seven different high performance cars•        Bronze: Pure Tech Racing 10 person package at PTR’s F1 racing facility includes FI tees, food and drinks. …plus iPods, Windows Mobile phones, X-box 360s, t-shirts and much more. There will be two qualifying events in Manchester on March 17th and London on March 31st, and the third qualifier as well as the grand finale will be held in the evening of Thursday April 7th at SQLBits. And if that isn’t cool enough, Fusion-io's Chief Scientist Steve Wozniak (yes, that Steve Wozniak, tech industry legend and co-founder of Apple) will be on hand in Brighton to hand out the prizes! If you'd like to take part you'll need to register, and since places are limited we recommend you do so right away. For more details and to register, go to http://www.crappycodegames.com/ The Games: In conjunction with SQL Bits, dbA-thletes (that’s you) will compete  head-to-head in one of three separate qualifying events to be held in Manchester, London and Brighton.  Four separate SQL  rounds make up the evening’s Games, and will challenge you to write code that pushes the boundaries of SQL performance.  The four events are: ?  The High Jump: Generate the highest I/O per second ?  The 100 m dash: Cumulative highest number of I/O’s in 60 seconds ?  The SSIS-athon: Load one billion row fact table in the shortest time ?  The Marathon: Generate the highest MB per second in 60 seconds

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  • Maintaining packages with code - Adding a property expression programmatically

    Every now and then I've come across scenarios where I need to update a lot of packages all in the same way. The usual scenario revolves around a group of packages all having been built off the same package template, and something needs to updated to keep up with new requirements, a new logging standard for example.You'd probably start by updating your template package, but then you need to address all your existing packages. Often this can run into the hundreds of packages and clearly that's not a job anyone wants to do by hand. I normally solve the problem by writing a simple console application that looks for files and patches any package it finds, and it is an example of this I'd thought I'd tidy up a bit and publish here. This sample will look at the package and find any top level Execute SQL Tasks, and change the SQL Statement property to use an expression. It is very simplistic working on top level tasks only, so nothing inside a Sequence Container or Loop will be checked but obviously the code could be extended for this if required. The code that actually sets the expression is shown below, the rest is just wrapper code to find the package and to find the task. /// <summary> /// The CreationName of the Tasks to target, e.g. Execute SQL Task /// </summary> private const string TargetTaskCreationName = "Microsoft.SqlServer.Dts.Tasks.ExecuteSQLTask.ExecuteSQLTask, Microsoft.SqlServer.SQLTask, Version=9.0.242.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91"; /// <summary> /// The name of the task property to target. /// </summary> private const string TargetPropertyName = "SqlStatementSource"; /// <summary> /// The property expression to set. /// </summary> private const string ExpressionToSet = "@[User::SQLQueryVariable]"; .... // Check if the task matches our target task type if (taskHost.CreationName == TargetTaskCreationName) { // Check for the target property if (taskHost.Properties.Contains(TargetPropertyName)) { // Get the property, check for an expression and set expression if not found DtsProperty property = taskHost.Properties[TargetPropertyName]; if (string.IsNullOrEmpty(property.GetExpression(taskHost))) { property.SetExpression(taskHost, ExpressionToSet); changeCount++; } } } This is a console application, so to specify which packages you want to target you have three options: Find all packages in the current folder, the default behaviour if no arguments are specified TaskExpressionPatcher.exe .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Find all packages in a specified folder, pass the folder as the argument TaskExpressionPatcher.exe C:\Projects\Alpha\Packages\ .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Find a specific package, pass the file path as the argument TaskExpressionPatcher.exe C:\Projects\Alpha\Packages\Package.dtsx The code was written against SQL Server 2005, but just change the reference to Microsoft.SQLServer.ManagedDTS to be the SQL Server 2008 version and it will work fine. If you get an error Microsoft.SqlServer.Dts.Runtime.DtsRuntimeException: The package failed to load due to error 0xC0011008… then check that the package is from the correct version of SSIS compared to the referenced assemblies, 2005 vs 2008 in other words. Download Sample Project TaskExpressionPatcher.zip (6 KB)

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  • How do you deal with intentionally bad code?

    - by mafutrct
    There are many stories about intentionally bad code, not only on TDWTF but also on SO. Typical cases include: Having a useless time-wasting construct (e.g. an empty loop counting to some huge value) so programmers can easily "speed up" the application by removing it when they are tasked to. Providing intentionally misleading, wrong or no documentation to generate expensive support requests. Readily generating errors, or worse, generating even though everything worked fine, locking up the application so an expensive support call is required to unlock. These points display a more or less malicious attitude (even though sometimes by accident), especially the first point occurs rather often. How should one deal with such constructs? Ignore the issue, or just remove the offending code? Notify their manager, or speak to the person who introduced the "feature"?

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  • Is there any reason to use "plain old data" classes?

    - by Michael
    In legacy code I occasionally see classes that are nothing but wrappers for data. something like: class Bottle { int height; int diameter; Cap capType; getters/setters, maybe a constructor } My understanding of OO is that classes are structures for data and the methods of operating on that data. This seems to preclude objects of this type. To me they are nothing more than structs and kind of defeat the purpose of OO. I don't think it's necessarily evil, though it may be a code smell. Is there a case where such objects would be necessary? If this is used often, does it make the design suspect?

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  • Code and Slides: Building the Account at a Glance ASP.NET MVC, EF Code First, HTML5, and jQuery Application

    - by dwahlin
    This presentation was given at the spring 2012 DevConnections conference in Las Vegas and is based on my Pluralsight course. The presentation shows how several different technologies including ASP.NET MVC, EF Code First, HTML5, jQuery, Canvas, SVG, JavaScript patterns, Ajax, and more can be integrated together to build a robust application. An example of the application in action is shown next: View more of my presentations here. The complete code (and associated SQL Server database) for the Account at a Glance application can be found here. Check out the full-length course on the topic at Pluralsight.com.

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  • *Code owner* system: is it an efficient way?

    - by sergzach
    There is a new developer in our team. An agile methodology is in use at our company. But the developer has another experience: he considers that particular parts of the code must be assigned to particular developers. So if one developer had created a program procedure or module it would be considered normal that all changes of the procedure/module would be made by him only. On the plus side, supposedly with the proposed approach we save common development time, because each developer knows his part of the code well and makes fixes fast. The downside is that developers don't know the system entirely. Do you think the approach will work well for a medium size system (development of a social network site)?

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  • Is there any reason to use "container" classes?

    - by Michael
    I realize the term "container" is misleading in this context - if anyone can think of a better term please edit it in. In legacy code I occasionally see classes that are nothing but wrappers for data. something like: class Bottle { int height; int diameter; Cap capType; getters/setters, maybe a constructor } My understanding of OO is that classes are structures for data and the methods of operating on that data. This seems to preclude objects of this type. To me they are nothing more than structs and kind of defeat the purpose of OO. I don't think it's necessarily evil, though it may be a code smell. Is there a case where such objects would be necessary? If this is used often, does it make the design suspect?

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  • I sold my source code to a client, can I now re-build similar code and sell to someone else?

    - by flashhag
    So we built a website and software for a client, charged our fee and handed over the code. The client then got a request from another company about the software. The client passed on the request but said since they owned the code they would need to recieve money for it. I'm thinking there are 2 options here: Work with the client as requested We've actually re-built the software, made it much better and use it for other projects. Am i in my rights to sell that direct to the company that enquired about it instead of going through the client? Any help on this would be much appreciated

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  • Organizing code for iOS app development

    - by KronoS
    I've been developing an app for the iOS platform, and as I've been going along, I've noticed that I've done a terrible job of keeping my files (.h, .m, .mm) organized. Is there any industry standards or best practices when it comes to organizing files for an iOS project? My files include custom classes (beside the view controllers), customized View Controllers, third-party content, code that works only on iOS 5.0+ and code that works on previous versions. What I'm looking for is a solution to keep things organized in a manner that others (or myself in years to come) can look at this and understand the basic structure of the application and not get lost in the multiple files found therein.

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  • HG: fork web app project to separate API code from app code

    - by cs_brandt
    I have a web app thats been in active development for about 8 months now and its becoming apparent that the project has a need to maintain a separation between app specific code and our OO Javascript API. What I would like to do is have another repository with the following general structure of the js API code. repo_name | +---build | +---build_tools | +---doc | +---src | +---js Of course this structure is different from the original web app directory structure. If I make changes to this new repository how could I pull in those changes to the web app repository without unintentionally removing files or modifying the directory structure of the web app repository?

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  • Is extensive documentation a code smell?

    - by Griffin
    Every library, open-source project, and SDK/API I've ever come across has come packaged with a (usually large) documentation file, and this seems contradictory to the wide-spread belief that good code needs little to no comments. What separates documentation from this programming methodology? a one to two page overview of a package seems reasonable, but elegant code combined with standard intelisense should have theoretically deprecated the practice of documentation by now IMO. I feel like companies only create detailed documentation and tutorials because its what they've always done. Why should developers have to constantly be searching through online documentation in order to learn how to do things when such information should be intrinsic to the classes, methods and namespaces?

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  • Which is more maintainable -- boolean assignment via if/else or boolean expression?

    - by Bret Walker
    Which would be considered more maintainable? if (a == b) c = true; else c = false; or c = (a == b); I've tried looking in Code Complete, but can't find an answer. I think the first is more readable (you can literally read it out loud), which I also think makes it more maintainable. The second one certainly makes more sense and reduces code, but I'm not sure it's as maintainable for C# developers (I'd expect to see this idiom more in, for example, Python).

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  • Nested languages code smell

    - by l0b0
    Many projects combine languages, for example on the web with the ubiquitous SQL + server-side language + markup du jour + JavaScript + CSS mix (often in a single function). Bash and other shell code is mixed with Perl and Python on the server side, evaled and sometimes even passed through sed before execution. Many languages support runtime execution of arbitrary code strings, and in some it seems to be fairly common practice. In addition to advice about security and separation of concerns, what other issues are there with this type of programming, what can be done to minimize it, and is it ever defensible (except in the "PHB on the shoulder" situation)?

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  • Resources on learning to program in machine code?

    - by AceofSpades
    I'm a student, fresh into programming and loving it, from Java to C++ and down to C. I moved backwards to the barebones and thought to go further down to Assembly. But, to my surprise, a lot of people said it's not as fast as C and there is no use. They suggested learning either how to program a kernel or writing a C compiler. My dream is to learn to program in binary (machine code) or maybe program bare metal (program micro-controller physically) or write bios or boot loaders or something of that nature. The only possible thing I heard after so much research is that a hex editor is the closest thing to machine language I could find in this age and era. Are there other things I'm unaware of? Are there any resources to learn to program in machine code? Preferably on a 8-bit micro-controller/microprocessor. This question is similar to mine, but I'm interested in practical learning first and then understanding the theory.

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  • Coordinating team code review sessions [closed]

    - by Wade Tandy
    My question has two parts: 1) In your team or organization, do you ever do in-person code reviews with all or part of a team, as opposed to online reviews using some sort of tool? 2) How do you structure these meetings? Do you choose to focus on one person's code in a given meeting? Do you look at everything? Take a random sample? Ask people on the team what they'd like to have looked at of theirs? I'd love to add this practice to my development team, so I'd like to hear how others are doing it.

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  • Code Analysis Error: Declare types in namespaces

    - by George
    Is VS2010, I analyzed my code and got this error: Warning 64 CA1050 : Microsoft.Design : 'ApplicationVariables' should be declared inside a namespace. C:\My\Code\BESI\BESI\App_Code\ApplicationVariables.vb 10 C:\...\BESI\ Here is some reference info on the error. Essentially, I tried to create a class to be used to access data in the Application object in a typed way. The warning message said unless I put my (ApplicationVariables) class in a Namespace, that I wouldn't be able to use it. But I am using it, so what gives? Also, here is a link to another StackOverflow article that talks about how to disable this warning in VS2008, but how would you disable it for 2010? There is no GlobalSuppressions.vb file for VS2010. Here is the code it is complaining a bout: Public Class ApplicationVariables 'Shared Sub New() 'End Sub 'New Public Shared Property PaymentMethods() As PaymentMethods Get Return CType(HttpContext.Current.Application.Item("PaymentMethods"), PaymentMethods) End Get Set(ByVal value As PaymentMethods) HttpContext.Current.Application.Item("PaymentMethods") = value End Set End Property 'Etc, Etc... End Class

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  • Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 2 – Table per Type (TPT)

    - by mortezam
    In the previous blog post you saw that there are three different approaches to representing an inheritance hierarchy and I explained Table per Hierarchy (TPH) as the default mapping strategy in EF Code First. We argued that the disadvantages of TPH may be too serious for our design since it results in denormalized schemas that can become a major burden in the long run. In today’s blog post we are going to learn about Table per Type (TPT) as another inheritance mapping strategy and we'll see that TPT doesn’t expose us to this problem. Table per Type (TPT)Table per Type is about representing inheritance relationships as relational foreign key associations. Every class/subclass that declares persistent properties—including abstract classes—has its own table. The table for subclasses contains columns only for each noninherited property (each property declared by the subclass itself) along with a primary key that is also a foreign key of the base class table. This approach is shown in the following figure: For example, if an instance of the CreditCard subclass is made persistent, the values of properties declared by the BillingDetail base class are persisted to a new row of the BillingDetails table. Only the values of properties declared by the subclass (i.e. CreditCard) are persisted to a new row of the CreditCards table. The two rows are linked together by their shared primary key value. Later, the subclass instance may be retrieved from the database by joining the subclass table with the base class table. TPT Advantages The primary advantage of this strategy is that the SQL schema is normalized. In addition, schema evolution is straightforward (modifying the base class or adding a new subclass is just a matter of modify/add one table). Integrity constraint definition are also straightforward (note how CardType in CreditCards table is now a non-nullable column). Another much more important advantage is the ability to handle polymorphic associations (a polymorphic association is an association to a base class, hence to all classes in the hierarchy with dynamic resolution of the concrete class at runtime). A polymorphic association to a particular subclass may be represented as a foreign key referencing the table of that particular subclass. Implement TPT in EF Code First We can create a TPT mapping simply by placing Table attribute on the subclasses to specify the mapped table name (Table attribute is a new data annotation and has been added to System.ComponentModel.DataAnnotations namespace in CTP5): public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } [Table("BankAccounts")] public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } [Table("CreditCards")] public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } If you prefer fluent API, then you can create a TPT mapping by using ToTable() method: protected override void OnModelCreating(ModelBuilder modelBuilder) {     modelBuilder.Entity<BankAccount>().ToTable("BankAccounts");     modelBuilder.Entity<CreditCard>().ToTable("CreditCards"); } Generated SQL For QueriesLet’s take an example of a simple non-polymorphic query that returns a list of all the BankAccounts: var query = from b in context.BillingDetails.OfType<BankAccount>() select b; Executing this query (by invoking ToList() method) results in the following SQL statements being sent to the database (on the bottom, you can also see the result of executing the generated query in SQL Server Management Studio): Now, let’s take an example of a very simple polymorphic query that requests all the BillingDetails which includes both BankAccount and CreditCard types: projects some properties out of the base class BillingDetail, without querying for anything from any of the subclasses: var query = from b in context.BillingDetails             select new { b.BillingDetailId, b.Number, b.Owner }; -- var query = from b in context.BillingDetails select b; This LINQ query seems even more simple than the previous one but the resulting SQL query is not as simple as you might expect: -- As you can see, EF Code First relies on an INNER JOIN to detect the existence (or absence) of rows in the subclass tables CreditCards and BankAccounts so it can determine the concrete subclass for a particular row of the BillingDetails table. Also the SQL CASE statements that you see in the beginning of the query is just to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type) TPT ConsiderationsEven though this mapping strategy is deceptively simple, the experience shows that performance can be unacceptable for complex class hierarchies because queries always require a join across many tables. In addition, this mapping strategy is more difficult to implement by hand— even ad-hoc reporting is more complex. This is an important consideration if you plan to use handwritten SQL in your application (For ad hoc reporting, database views provide a way to offset the complexity of the TPT strategy. A view may be used to transform the table-per-type model into the much simpler table-per-hierarchy model.) SummaryIn this post we learned about Table per Type as the second inheritance mapping in our series. So far, the strategies we’ve discussed require extra consideration with regard to the SQL schema (e.g. in TPT, foreign keys are needed). This situation changes with the Table per Concrete Type (TPC) that we will discuss in the next post. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

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  • Can this be considered Clean Code / Best Practice?

    - by MRFerocius
    Guys, How are you doing today? I have the following question because I will follow this strategy for all my helpers (to deal with the DB entities) Is this considered a good practice or is it going to be unmaintainable later? public class HelperArea : AbstractHelper { event OperationPerformed<Area> OnAreaInserting; event OperationPerformed<Area> OnAreaInserted; event OperationPerformed<Area> OnExceptionOccured; public void Insert(Area element) { try { if (OnAreaInserting != null) OnAreaInserting(element); DBase.Context.Areas.InsertOnSubmit(new AtlasWFM_Mapping.Mapping.Area { areaDescripcion = element.Description, areaNegocioID = element.BusinessID, areaGUID = Guid.NewGuid(), areaEstado = element.Status, }); DBase.Context.SubmitChanges(); if (OnAreaInserted != null) OnAreaInserted(element); } catch (Exception ex) { LogManager.ChangeStrategy(LogginStrategies.EVENT_VIEWER); LogManager.LogError(new LogInformation { logErrorType = ErrorType.CRITICAL, logException = ex, logMensaje = "Error inserting Area" }); if (OnExceptionOccured != null) OnExceptionOccured(elemento); } } I want to know if it is a good way to handle the event on the Exception to let subscribers know that there has been an exception inserting that Area. And the way to log the Exception, is is OK to do it this way? Any suggestion to make it better?

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