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• Avoiding bloated Domain Objects

  - by djcredo

  We're trying to move data from our bloated Service layer into our Domain layer using a DDD approach. We currently have a lot of business logic in our services, which is spread out all over the place and doesn't benefit from inheritance. We have a central Domain class which is the focus of most of our work - a Trade. The Trade object will know how to price itself, how to estimate risk, validate itself, etc. We can then replace conditionals with polymorphism. Eg: SimpleTrade will price itself one way, but ComplexTrade will price itself another. However, we are worried that this will bloat the Trade class(s). It really should be in charge of its own processing but the class size is going to increase exponentially as more features are added. So we have choices: Put processing logic in Trade class. Processing logic is now polymorphic based on the type of the trade, but Trade class is now has multiple responsibilites (pricing, risk, etc) and is large Put processing logic into other class such as TradePricingService. No longer polymorphic with the Trade inheritance tree, but classes are smaller and easier to test. What would be the suggested approach?

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• How to learn to deliver quality software designs when working on a tight deadline?

  - by chester89

  I read many books about how to design great software, but I kind of struggle to come up with a good design decisions when it comes to business apps, especially when the timeframe is tough. In the company I currently work for, the following situation happen all the time: my teamlead tells me that there's a task to do, I call some guy or a girl from business who tells me exactly what is it they want, and then I start coding. The task always fits in some existing application (we do only web apps or web services), usually it's purpose is to pull data from one datasource and put into the other one, with some business logic attached in the process. I start coding and then, after spending some time on a problem, my code didn't work as expected - either because of technical mistake or my lack of knowledge of the domain. The business is ringing me 2-3 times a day to hurry me up. I ask my team lead to help, he comes up, sees my code and goes like 'What's this?'. Then he throws away about half of my code, including all the design decisions I made, writes 2-3 methods that does the job (each of them usually 200-300 lines long or more, by the way), and task is complete, code works as it should have. The guy is smarter than me, obviously, and I'm aware of that. My goal is to be better software developer, that means write better code, not finish the job quicker with some crappy code. And the thing is, when I have enough time to tackle a problem, I can come up with a design that is good (in my opinion, of course), but I fall short to do so when I'm on a tight deadline. What should I do? I am fully aware that it's rather vague explanation, but please bear with me

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• OOP Design: relationship between entity classes

  - by beginner_

  I have at first sight a simple issue but can't wrap my head around on how to solve. I have an abstract class Compound. A Compound is made up of Structures. Then there is also a Container which holds 1 Compound. A "special" implementation of Compound has Versions. For that type of Compound I want the Container to hold the Versionof the Compound and not the Compound itself. You could say "just create an interface Containable" and a Container holds 1 Containable. However that won't work. The reason is I'm creating a framework and the main part of that framework is to simplify storing and especially searching for special data type held by Structure objects. Hence to search for Containers which contain a Compound made up of a specific Structure requires that the "Path" from Containerto Structure is well defined (Number of relationships or joins). I hope this was understandable. My question is how to design the classes and relationships to be able to do what I outlined.

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• How to optimize Core Data query for full text search

  - by dk

  Can I optimize a Core Data query when searching for matching words in a text? (This question also pertains to the wisdom of custom SQL versus Core Data on an iPhone.) I'm working on a new (iPhone) app that is a handheld reference tool for a scientific database. The main interface is a standard searchable table view and I want as-you-type response as the user types new words. Words matches must be prefixes of words in the text. The text is composed of 100,000s of words. In my prototype I coded SQL directly. I created a separate "words" table containing every word in the text fields of the main entity. I indexed words and performed searches along the lines of SELECT id, * FROM textTable JOIN (SELECT DISTINCT textTableId FROM words WHERE word BETWEEN 'foo' AND 'fooz' ) ON id=textTableId LIMIT 50 This runs very fast. Using an IN would probably work just as well, i.e. SELECT * FROM textTable WHERE id IN (SELECT textTableId FROM words WHERE word BETWEEN 'foo' AND 'fooz' ) LIMIT 50 The LIMIT is crucial and allows me to display results quickly. I notify the user that there are too many to display if the limit is reached. This is kludgy. I've spent the last several days pondering the advantages of moving to Core Data, but I worry about the lack of control in the schema, indexing, and querying for an important query. Theoretically an NSPredicate of textField MATCHES '.*\bfoo.*' would just work, but I'm sure it will be slow. This sort of text search seems so common that I wonder what is the usual attack? Would you create a words entity as I did above and use a predicate of "word BEGINSWITH 'foo'"? Will that work as fast as my prototype? Will Core Data automatically create the right indexes? I can't find any explicit means of advising the persistent store about indexes. I see some nice advantages of Core Data in my iPhone app. The faulting and other memory considerations allow for efficient database retrievals for tableview queries without setting arbitrary limits. The object graph management allows me to easily traverse entities without writing lots of SQL. Migration features will be nice in the future. On the other hand, in a limited resource environment (iPhone) I worry that an automatically generated database will be bloated with metadata, unnecessary inverse relationships, inefficient attribute datatypes, etc. Should I dive in or proceed with caution?

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• Dynamic data-entry value store

  - by simendsjo

  I'm creating a data-entry application where users are allowed to create the entry schema. My first version of this just created a single table per entry schema with each entry spanning a single or multiple columns (for complex types) with the appropriate data type. This allowed for "fast" querying (on small datasets as I didn't index all columns) and simple synchronization where the data-entry was distributed on several databases. I'm not quite happy with this solution though; the only positive thing is the simplicity... I can only store a fixed number of columns. I need to create indexes on all columns. I need to recreate the table on schema changes. Some of my key design criterias are: Very fast querying (Using a simple domain specific query language) Writes doesn't have to be fast Many concurrent users Schemas will change often Schemas might contain many thousand columns The data-entries might be distributed and needs syncronization. Preferable MySQL and SQLite - Databases like DB2 and Oracle is out of the question. Using .Net/Mono I've been thinking of a couple of possible designs, but none of them seems like a good choice. Solution 1: Union like table containing a Type column and one nullable column per type. This avoids joins, but will definitly use a lot of space. Solution 2: Key/value store. All values are stored as string and converted when needed. Also use a lot of space, and of course, I hate having to convert everything to string. Solution 3: Use an xml database or store values as xml. Without any experience I would think this is quite slow (at least for the relational model unless there is some very good xpath support). I also would like to avoid an xml database as other parts of the application fits better as a relational model, and being able to join the data is helpful. I cannot help to think that someone has solved (some of) this already, but I'm unable to find anything. Not quite sure what to search for either... I know market research is doing something like this for their questionnaires, but there are few open source implementations, and the ones I've found doesn't quite fit the bill. PSPP has much of the logic I'm thinking of; primitive column types, many columns, many rows, fast querying and merging. Too bad it doesn't work against a database.. And of course... I don't need 99% of the provided functionality, but a lot of stuff not included. I'm not sure this is the right place to ask such a design related question, but I hope someone here has some tips, know of any existing work, or can point me to a better place to ask such a question. Thanks in advance!

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• Do I suffer from encapsulation overuse?

  - by Florenc

  I have noticed something in my code in various projects that seems like code smell to me and something bad to do, but I can't deal with it. While trying to write "clean code" I tend to over-use private methods in order to make my code easier to read. The problem is that the code is indeed cleaner but it's also more difficult to test (yeah I know I can test private methods...) and in general it seems a bad habit to me. Here's an example of a class that reads some data from a .csv file and returns a group of customers (another object with various fields and attributes). public class GroupOfCustomersImporter { //... Call fields .... public GroupOfCustomersImporter(String filePath) { this.filePath = filePath; customers = new HashSet<Customer>(); createCSVReader(); read(); constructTTRP_Instance(); } private void createCSVReader() { //.... } private void read() { //.... Reades the file and initializes the class attributes } private void readFirstLine(String[] inputLine) { //.... Method used by the read() method } private void readSecondLine(String[] inputLine) { //.... Method used by the read() method } private void readCustomerLine(String[] inputLine) { //.... Method used by the read() method } private void constructGroupOfCustomers() { //this.groupOfCustomers = new GroupOfCustomers(**attributes of the class**); } public GroupOfCustomers getConstructedGroupOfCustomers() { return this.GroupOfCustomers; } } As you can see the class has only a constructor which calls some private methods to get the job done, I know that's not a good practice not a good practice in general but I prefer to encapsulate all the functionality in the class instead of making the methods public in which case a client should work this way: GroupOfCustomersImporter importer = new GroupOfCustomersImporter(filepath) importer.createCSVReader(); read(); GroupOfCustomer group = constructGoupOfCustomerInstance(); I prefer this because I don't want to put useless lines of code in the client's side code bothering the client class with implementation details. So, Is this actually a bad habit? If yes, how can I avoid it? Please note that the above is just a simple example. Imagine the same situation happening in something a little bit more complex.

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• Excel tables creation upon MySQL data import (new feature in MySQL for Excel 1.2.x)

  - by Javier Treviño

  In this blog post we are going to talk about one of the features included since MySQL for Excel 1.2.0, you can install the latest GA or maintenance version using the MySQL Installer or optionally you can download directly any GA or non-GA version from the MySQL Developer Zone. Remember how easy is to dump data from a MySQL table, view or stored procedure to an Excel worksheet? (If you don't you can check out this other post: How To - Guide to Importing Data from a MySQL Database to Excel using MySQL for Excel). In version 1.2.0 we introduced some advanced options for the Import MySQL Data operation regarding Excel tables. The Advanced Options dialog shown above is accessible from any Import Data dialog. When the Create an Excel table for the imported MySQL table data option is checked (which is by default), MySQL for Excel will create an Excel table (also known in Excel jargon as a ListObject) from the Excel range containing the imported MySQL data. This "little feature" enables the right-away usage of the Excel table in data analysis, like including it for summarization on a PivotTable, including a summarization row at the end of the table's data, sorting or filtering the table's data by clicking the drop-down button next to each column's header, among other actions. The Excel tables that are created automatically from imported MySQL data will have a name like [UserPrefix].<SchemaName>.<DbObjectName> for tables and views, and <Prefix>.<SchemaName>.<ProcedureName>.<ResultSetName> for stored procedures.  Notice the first piece of the name is an optional [UserPrefix], the prefix is only used if the Prefix Excel tables with the following text option is checked, notice that the suggested prefix is "MySQL" but it can be changed to whatever text is suitable for you. Excel tables must have a table style so they are easily identified. There are a lot of predefined Excel table styles, by default the MySqlDefault style is applied, which is the style you have seen applied to imported data for Edit Sessions, and which adds simple and elegant formatting to the table. If you wish to change it to any of the predefined Excel table style you can do it through the drop-down list on the Use style [[styles drop-down]] for the new Excel table option. Excel tables are the basic construction blocks for building data analysis or self-service Business Intelligence using other more advanced Excel tools like Power Pivot, Power View or Power Map. This feature empowers imported MySQL data to use it in more advanced ways.  We hope you give this and the other new features in the 1.2.x version family a try! Remember that your feedback is very important for us, so drop us a message and follow us: MySQL on Windows (this) Blog: https://blogs.oracle.com/MySqlOnWindows/ MySQL for Excel forum: http://forums.mysql.com/list.php?172 Facebook: http://www.facebook.com/mysql YouTube channel: https://www.youtube.com/user/MySQLChannel Cheers!

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• How to recover data files from xampp-windows to xampp-linux after crash?

  - by David Buehler

  My Windows box died after I developed a database in xampp on it; fortunately I have a backup of the entire F:/TestWeb/Xampp partition. Unfortunately, I did not do an Export (nor dump) of the "Lws2" database before the crash. I have replaced the defunct machine with one running Mint7 (based on Ubuntu 9.04 "Jaunty Jackalope") and installed xampp-linux into the /opt partition, so the new xampp now runs fine in /opt/lampp, and says all the elements are secured by passwords (which I just assigned during this installation.) I assumed that Xamp-Windows installed in November would migrate easily to xampp-linux installed iin February -- a bad assumption. It apparently would have been simple if I had known enough to do an Export or a Dump before the crash, but.... The backup was done to a Network Attached Storage drive, which is formatted as "vfat" so the backup does not carry with it any valid ownership permissions from MySql on NTFS. I now see from my backup that the old data resided in \TestWeb\Xampp\Mysql\Data\Lws2\ and consists of 7 ".frm" files which define my tables. The actual data -- I suppose a ".sql" file or files -- has disappeared, and I am resigning myself to two days of retyping it. But I do not wish to do the table layouts all over again. So I copied Data tree to /opt/lampp/Data -- PhpMyAdmin does not see it. So I copied Lws2 tree to /opt/lampp/Lws2 -- PhpMyAdmin does not see it. So I copied Data tree to /opt/lampp/var/mysql/Data -- PhpMyAdmin does not see it. So I copied Lws2 tree to /opt/lampp/var/mysql/Lws2 -- PhpMyAdmin does not see it. So I adjusted all the permissions to stop saying owner "nobody" to owner "root" and gave full permissions to all groups and to all others, with permissions percolating down, in all 4 trees. You guessed it -- PhpMyAdmin does not see any database named Lws2, only its 4 default ones. I double-checked the permissions and rebooted Linux and repeated the tests. At some point in that process I did see PhpMyAdmin showing "lws2(7)" but when I clicked on it I saw a "no table found" message. I have not been able to recreate that experience. Apparently there are some setup files for MySql and for PhpMyAdmin which need to be set up by running a wizard or two or by editing the files directly. I grepped the TestWeb tree and found an old "ldir = "C:TestWeb\Xampp\MySql\" and a "DataDir = C:TestWeb\Xampp\MySql\" in a .php file and in a .bat file, but I cannot find the corresponding config file names on the /opt partition/ -- so it looks as if these wizards have not been run to create them. What config files files does Linux use to setup MySql config files for PhpMyAdmin? What wizards do I need to run to point the MySql engine and the PhpMyAdmin at the folder /opt/lampp/data/ with its lws2 folder inside it? Or which files do I need to edit, with a sample of what it normally says under Linux? Incidentally, I remember I converted from MyISAM with its .MYD and .MYI files to InnoDB after entering only a small amount of the data -- and I do not know what file types to look for -- perhaps my data is still there but under another guise or in another place? Is it something as simple as linux needing to see "/data/" instead of /Data? I will check that out while waiting for a response. If anyone can point me to documentation that discusses this level of detail -- I will read it avidly! In any case, thanks for any clarification you can give on this thorny problem. wizdum

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• When following SRP, how should I deal with validating and saving entities?

  - by Kristof Claes

  I've been reading Clean Code and various online articles about SOLID lately, and the more I read about it, the more I feel like I don't know anything. Let's say I'm building a web application using ASP.NET MVC 3. Let's say I have a UsersController with a Create action like this: public class UsersController : Controller { public ActionResult Create(CreateUserViewModel viewModel) { } } In that action method I want to save a user to the database if the data that was entered is valid. Now, according to the Single Responsibility Principle an object should have a single responsibility, and that responsibility should be entirely encapsulated by the class. All its services should be narrowly aligned with that responsibility. Since validation and saving to the database are two separate responsibilities, I guess I should create to separate class to handle them like this: public class UsersController : Controller { private ICreateUserValidator validator; private IUserService service; public UsersController(ICreateUserValidator validator, IUserService service) { this.validator = validator; this.service= service; } public ActionResult Create(CreateUserViewModel viewModel) { ValidationResult result = validator.IsValid(viewModel); if (result.IsValid) { service.CreateUser(viewModel); return RedirectToAction("Index"); } else { foreach (var errorMessage in result.ErrorMessages) { ModelState.AddModelError(String.Empty, errorMessage); } return View(viewModel); } } } That makes some sense to me, but I'm not at all sure that this is the right way to handle things like this. It is for example entirely possible to pass an invalid instance of CreateUserViewModel to the IUserService class. I know I could use the built in DataAnnotations, but what when they aren't enough? Image that my ICreateUserValidator checks the database to see if there already is another user with the same name... Another option is to let the IUserService take care of the validation like this: public class UserService : IUserService { private ICreateUserValidator validator; public UserService(ICreateUserValidator validator) { this.validator = validator; } public ValidationResult CreateUser(CreateUserViewModel viewModel) { var result = validator.IsValid(viewModel); if (result.IsValid) { // Save the user } return result; } } But I feel I'm violating the Single Responsibility Principle here. How should I deal with something like this?

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• Liskov principle: violation by type-hinting

  - by Elias Van Ootegem

  According to the Liskov principle, a construction like the one below is invalid, as it strengthens a pre-condition. I know the example is pointless/nonsense, but when I last asked a question like this, and used a more elaborate code sample, it seemed to distract people too much from the actual question. //Data models abstract class Argument { protected $value = null; public function getValue() { return $this->value; } abstract public function setValue($val); } class Numeric extends Argument { public function setValue($val) { $this->value = $val + 0;//coerce to number return $this; } } //used here: abstract class Output { public function printValue(Argument $arg) { echo $this->format($arg); return $this; } abstract public function format(Argument $arg); } class OutputNumeric extends Output { public function format(Numeric $arg)//<-- VIOLATION! { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } My question is this: Why would this kind of "violation" be considered harmful? So much so that some languages, like the one I used in this example (PHP), don't even allow this? I'm not allowed to strengthen the type-hint of an abstract method but, by overriding the printValue method, I am allowed to write: class OutputNumeric extends Output { final public function printValue(Numeric $arg) { echo $this->format($arg); } public function format(Argument $arg) { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } But this would imply repeating myself for each and every child of Output, and makes my objects harder to reuse. I understand why the Liskov principle exists, don't get me wrong, but I find it somewhat difficult to fathom why the signature of an abstract method in an abstract class has to be adhered to so much stricter than a non-abstract method. Could someone explain to me why I'm not allowed to hind at a child class, in a child class? The way I see it, the child class OutputNumeric is a specific use-case of Output, and thus might need a specific instance of Argument, namely Numeric. Is it really so wrong of me to write code like this?

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• Storing game objects with generic object information

  - by Mick

  In a simple game object class, you might have something like this: public abstract class GameObject { protected String name; // other properties protected double x, y; public GameObject(String name, double x, double y) { // etc } // setters, getters } I was thinking, since a lot of game objects (ex. generic monsters) will share the same name, movement speed, attack power, etc, it would be better to have all that information shared between all monsters of the same type. So I decided to have an abstract class "ObjectData" to hold all this shared information. So whenever I create a generic monster, I would use the same pre-created "ObjectData" for it. Now the above class becomes more like this: public abstract class GameObject { protected ObjectData data; protected double x, y; public GameObject(ObjectData data, double x, double y) { // etc } // setters, getters public String getName() { return data.getName(); } } So to tailor this specifically for a Monster (could be done in a very similar way for Npcs, etc), I would add 2 classes. Monster which extends GameObject, and MonsterData which extends ObjectData. Now I'll have something like this: public class Monster extends GameObject { public Monster(MonsterData data, double x, double y) { super(data, x, y); } } This is where my design question comes in. Since MonsterData would hold data specific to a generic monster (and would vary with what say NpcData holds), what would be the best way to access this extra information in a system like this? At the moment, since the data variable is of type ObjectData, I'll have to cast data to MonsterData whenever I use it inside the Monster class. One solution I thought of is this, but this might be bad practice: public class Monster extends GameObject { private MonsterData data; // <- this part here public Monster(MonsterData data, double x, double y) { super(data, x, y); this.data = data; // <- this part here } } I've read that for one I should generically avoid overwriting the underlying classes variables. What do you guys think of this solution? Is it bad practice? Do you have any better solutions? Is the design in general bad? How should I redesign this if it is? Thanks in advanced for any replies, and sorry about the long question. Hopefully it all makes sense!

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• Fraud and Anomaly Detection using Oracle Data Mining YouTube-like Video

  - by chberger

  I've created and recorded another YouTube-like presentation and "live" demos of Oracle Advanced Analytics Option, this time focusing on Fraud and Anomaly Detection using Oracle Data Mining.  [Note:  It is a large MP4 file that will open and play in place.  The sound quality is weak so you may need to turn up the volume.] Data is your most valuable asset. It represents the entire history of your organization and its interactions with your customers.  Predictive analytics leverages data to discover patterns, relationships and to help you even make informed predictions.   Oracle Data Mining (ODM) automatically discovers relationships hidden in data.  Predictive models and insights discovered with ODM address business problems such as:  predicting customer behavior, detecting fraud, analyzing market baskets, profiling and loyalty.  Oracle Data Mining, part of the Oracle Advanced Analytics (OAA) Option to the Oracle Database EE, embeds 12 high performance data mining algorithms in the SQL kernel of the Oracle Database. This eliminates data movement, delivers scalability and maintains security.  But, how do you find these very important needles or possibly fraudulent transactions and huge haystacks of data? Oracle Data Mining’s 1 Class Support Vector Machine algorithm is specifically designed to identify rare or anomalous records.  Oracle Data Mining's 1-Class SVM anomaly detection algorithm trains on what it believes to be considered “normal” records, build a descriptive and predictive model which can then be used to flags records that, on a multi-dimensional basis, appear to not fit in--or be different.  Combined with clustering techniques to sort transactions into more homogeneous sub-populations for more focused anomaly detection analysis and Oracle Business Intelligence, Enterprise Applications and/or real-time environments to "deploy" fraud detection, Oracle Data Mining delivers a powerful advanced analytical platform for solving important problems.  With OAA/ODM you can find suspicious expense report submissions, flag non-compliant tax submissions, fight fraud in healthcare claims and save huge amounts of money in fraudulent claims  and abuse.   This presentation and several brief demos will show Oracle Data Mining's fraud and anomaly detection capabilities.  

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• How far should an entity take care of its properties values by itself?

  - by Kharlos Dominguez

  Let's consider the following example of a class, which is an entity that I'm using through Entity Framework. - InvoiceHeader - BilledAmount (property, decimal) - PaidAmount (property, decimal) - Balance (property, decimal) I'm trying to find the best approach to keep Balance updated, based on the values of the two other properties (BilledAmount and PaidAmount). I'm torn between two practices here: Updating the balance amount every time BilledAmount and PaidAmount are updated (through their setters) Having a UpdateBalance() method that the callers would run on the object when appropriate. I am aware that I can just calculate the Balance in its getter. However, it isn't really possible because this is an entity field that needs to be saved back to the database, where it has an actual column, and where the calculated amount should be persisted to. My other worry about the automatically updating approach is that the calculated values might be a little bit different from what was originally saved to the database, due to rounding values (an older version of the software, was using floats, but now decimals). So, loading, let's say 2000 entities from the database could change their status and make the ORM believe that they have changed and be persisted back to the database the next time the SaveChanges() method is called on the context. It would trigger a mass of updates that I am not really interested in, or could cause problems, if the calculation methods changed (the entities fetched would lose their old values to be replaced by freshly recalculated ones, simply by being loaded). Then, let's take the example even further. Each invoice has some related invoice details, which also have BilledAmount, PaidAmount and Balance (I'm simplifying my actual business case for the sake of the example, so let's assume the customer can pay each item of the invoice separately rather than as a whole). If we consider the entity should take care of itself, any change of the child details should cause the Invoice totals to change as well. In a fully automated approach, a simple implementation would be looping through each detail of the invoice to recalculate the header totals, every time one the property changes. It probably would be fine for just a record, but if a lot of entities were fetched at once, it could create a significant overhead, as it would perform this process every time a new invoice detail record is fetched. Possibly worse, if the details are not already loaded, it could cause the ORM to lazy-load them, just to recalculate the balances. So far, I went with the Update() method-way, mainly for the reasons I explained above, but I wonder if it was right. I'm noticing I have to keep calling these methods quite often and at different places in my code and it is potential source of bugs. It also has a detrimental effect on data-binding because when the properties of the detail or header changes, the other properties are left out of date and the method has no way to be called. What is the recommended approach in this case?

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• How should I refactor switch statements like this (Switching on type) to be more OO?

  - by Taytay

  I'm seeing some code like this in our code base, and want to refactor it: (Typescript psuedocode follows): class EntityManager{ private findEntityForServerObject(entityType:string, serverObject:any):IEntity { var existingEntity:IEntity = null; switch(entityType) { case Types.UserSetting: existingEntity = this.getUserSettingByUserIdAndSettingName(serverObject.user_id, serverObject.setting_name); break; case Types.Bar: existingEntity = this.getBarByUserIdAndId(serverObject.user_id, serverObject.id); break; //Lots more case statements here... } return existingEntity; } } The downsides of switching on type are self-explanatory. Normally, when switching behavior based on type, I try to push the behavior into subclasses so that I can reduce this to a single method call, and let polymorphism take care of the rest. However, the following two things are giving me pause: 1) I don't want to couple the serverObject with the class that is storing all of these objects. It doesn't know where to look for entities of a certain type. And unfortunately, the identity of a type of ServerObject varies with the type of ServerObject. (So sometimes it's just an ID, other times it's a combination of an id and a uniquely identifying string, etc). And this behavior doesn't belong down there on those subclasses. It is the responsibility of the EntityManager and its delegates. 2) In this case, I can't modify the ServerObject classes since they're plain old data objects. It should be mentioned that I've got other instances of the above method that take a parameter like "IEntity" and proceed to do almost the same thing (but slightly modify the name of the methods they're calling to get the identity of the entity). So, we might have: case Types.Bar: existingEntity = this.getBarByUserIdAndId(entity.getUserId(), entity.getId()); break; So in that case, I can change the entity interface and subclasses, but this isn't behavior that belongs in that class. So, I think that points me to some sort of map. So eventually I will call: private findEntityForServerObject(entityType:string, serverObject:any):IEntity { return aMapOfSomeSort[entityType].findByServerObject(serverObject); } private findEntityForEntity(someEntity:IEntity):IEntity { return aMapOfSomeSort[someEntity.entityType].findByEntity(someEntity); } Which means I need to register some sort of strategy classes/functions at runtime with this map. And again, I darn well better remember to register one for each my my types, or I'll get a runtime exception. Is there a better way to refactor this? I feel like I'm missing something really obvious here.

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• Core Data migration problem: "Persistent store migration failed, missing source managed object model

  - by John Gallagher

  The Background A Cocoa Non Document Core Data project with two Managed Object Models. Model 1 stays the same. Model 2 has changed, so I want to migrate the store. I've created a new version by Design Data Model Add Model Version in Xcode. The difference between versions is a single relationship that's been changed from to a one to many. I've made my changes to the model, then saved. I've made a new Mapping Model that has the old model as a source and new model as a destination. I've ensured all Mapping Models and Data Models and are being compiled and all are copied to the Resource folder of my app bundle. I've switched on migrations by passing in a dictionary with the NSMigratePersistentStoresAutomaticallyOption key as [NSNumber numberWithBool:YES] when adding the Persistent Store. Rather than merging all models in the bundle, I've specified the two models I want to use (model 1 and the new version of model 2) and merged them using modelByMergingModels: The Problem No matter what I do to migrate, I get the error message: "Persistent store migration failed, missing source managed object model." What I've Tried I clean after every single build. I've tried various combinations of having only the model I'm migrating to in Resources, being compiled, or both. Since the error message implies it can't find the source model for my migration, I've tried having every version of the model in both the Resources folder and being compiled. I've made sure I'm not making a really basic error by switching back to the original version of my data model. The app runs fine. I've deleted the Mapping Model and the new version of the model, cleaned, then recreated both. I've tried making a different change in the new model - deleting an entity instead. I'm at my wits end. I can't help but think I've made a huge mistake somewhere that I'm not seeing. Any ideas?

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• How to best transfer large payloads of data using wsHttp with WCF with message security

  - by jpierson

  I have a case where I need to transfer large amounts of serialized object graphs (via NetDataContractSerializer) using WCF using wsHttp. I'm using message security and would like to continue to do so. Using this setup I would like to transfer serialized object graph which can sometimes approach around 300MB or so but when I try to do so I've started seeing a exception of type System.InsufficientMemoryException appear. After a little research it appears that by default in WCF that a result to a service call is contained within a single message by default which contains the serialized data and this data is buffered by default on the server until the whole message is completely written. Thus the memory exception is being caused by the fact that the server is running out of memory resources that it is allowed to allocate because that buffer is full. The two main recommendations that I've come across are to use streaming or chunking to solve this problem however it is not clear to me what that involves and whether either solution is possible with my current setup (wsHttp/NetDataContractSerializer/Message Security). So far I understand that to use streaming message security would not work because message encryption and decryption need to work on the whole set of data and not a partial message. Chunking however sounds like it might be possible however it is not clear to me how it would be done with the other constraints that I've listed. If anybody could offer some guidance on what solutions are available and how to go about implementing it I would greatly appreciate it. Related resources: Chunking Channel How to: Enable Streaming Large attachments over WCF Custom Message Encoder Another spotting of InsufficientMemoryException I'm also interested in any type of compression that could be done on this data but it looks like I would probably be best off doing this at the transport level once I can transition into .NET 4.0 so that the client will automatically support the gzip headers if I understand this properly.

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• How to import data to SAP

  - by Mehmet AVSAR

  Hi, As a complete stranger in town of SAP, I want to transfer my own application's (mobile salesforce automation) data to SAP. My application has records of customers, stocks, inventory, invoices (and waybills), cheques, payments, collections, stock transfer data etc. I have an additional database which holds matchings of records. ie. A customer with ID 345 in my application has key 120-035-0223 in SAP. Every record, for sure, has to know it's counterpart, including parameters. After searching Google and SAP help site for a day, I covered that it's going to be a bit more pain than I expected. Especially SAP site does not give even a clue on it. Say I couldn't find. We transferred our data to some other ERP systems, some of which wanted XML files, some other exposed their APIs. My point is, is Sql Server's SSIS an option for me? I hope it is, so I can fight on my own territory. Since client requests would vary a lot, I count flexibility as most important criteria. Also, I want to transfer as much data as I could. Any help is appreciated. Regards,

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• Image Wells, Core Data, and Sqlite files.

  - by Sway

  I've got a mac application that I've developed. I use it to create sqlite files that are bundled with my iphone app. The mac app uses Core Data and bindings and is working fine except for one "weird" issue. I use an NSImageView (or Image Well) to allow me to drag and drop jpg files. This is bound through to an optional binary attribute in my model class. For some reason when I drag and drop a 4k jpg file it onto the image well and save the sqlite file. The data saved to the binary column is over 15 times larger than it should be. Whereas if I use an application like SQLiteManager and add the image into the row in the database. The binary data is the correct (expected size). File 4k jpg Actual size: 2371. Persisted via Core Data size: 35810. Can anyone give me a suggestion as to why this might be happening? Do I need to set some setting in Interface Builder or write some custom code?

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• Accessing data stored in another unit Delphi

  - by Hendriksen123

  In Unit2 of my program i have the following code: TValue = Record NewValue, OldValue, SavedValue : Double; end; TData = Class(TObject) Public EconomicGrowth : TValue; Inflation : TValue; Unemployment : TValue; CurrentAccountPosition : TValue; AggregateSupply : TValue; AggregateDemand : TValue; ADGovernmentSpending : TValue; ADConsumption : TValue; ADInvestment : TValue; ADNetExports : TValue; OverallTaxation : TValue; GovernmentSpending : TValue; InterestRates : TValue; IncomeTax : TValue; Benefits : TValue; TrainingEducationSpending : TValue; End; I then declare Data : TData in the Var. when i try to do the following however in Unit1: ShowMessage(FloatToStr(Unit2.Data.Inflation.SavedValue)); I get an EAccessViolation message. Is there any way to access the data stored in 'Data' from Unit1 without getting errors?

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• How to show data in dataTable lable:data in jsf

  - by palakolanusrinu

  Hi How to display lable: data name: srinu in multiple rows using dataTable in jsf right now i'm getting like | lable | data| data srinu i want it in this formate lable: data name: srinu code which used is <h:dataTable id="fundInfo" value="#{clientFundInfo}" border="1" var="client" first="0" rows="5" rules="all"> <h:column> <h:outputText value="CLIENT:"/> <h:outputText value="#{client.clientName}"></h:outputText> </h:column> <h:column> <h:outputText value="FUND:"/> <h:outputText value="#{client.fundName}"></h:outputText> </h:column> <h:column> <h:outputText value="Employer Identification Number:"/> <h:outputText value="#{client.empIdentificationNum}"></h:outputText> </h:column> <h:column><h:outputText value="FISCAL YEAR ENDED:"/> <h:outputText value="#{client.fye}"></h:outputText> </h:column> <h:column><h:outputText value="Shares Outstanding"/> <h:outputText value="#{client.sharesOutstanding}"></h:outputText> </h:column> </h:dataTable>

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• jquery slide to attribute with specific data attribute value

  - by Alex M

  Ok, so I have the following nav with absolute urls: <ul class="nav navbar-nav" id="main-menu"> <li class="first active"><a href="http://example.com/" title="Home">Home</a></li> <li><a href="http://example.com/about.html" title="About">About</a></li> <li><a href="http://example.com/portfolio.html" title="Portfolio">Portfolio</a></li> <li class="last"><a href="example.com/contact.html" title="Contact">Contact</a></li> </ul> and then articles with the following data attributes: <article class="row page" id="about" data-url="http://example.com/about.html"> <div class="one"> </div> <div class="two" </div> </article> and when you click the link in the menu I would like to ignore the fact it is a hyperlink and slide to the current article based on its attribute data-url. I started with what I think is the obvious: $('#main-menu li a').on('click', function(event) { event.preventDefault(); var pageUrl = $(this).attr('href'); )}; and have tried find and animate but then I don't know how to reference the article with data-url="http://example.com/about.html". Any help would be most appreciated. Thanks

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• Syncing two separate structures to the same master data

  - by Mike Burton

  I've got multiple structures to maintain in my application. All link to the same records, and one of them could be considered the "master" in that it reflects actual relationships held in files on disk. The other structures are used to "call out" elements of the main design for purchase and work orders. I'm struggling to come up with a pattern that deals appropriately with changes to the master data. As an example, the following trees might refer to the same data: A |_ B |_ C |_ D |_ E |_ B |_ C |_ D A |_ B E C |_ D A |_ B C D E These secondary structures follow internal rules, but their overall structure is usually user-determined. In all cases (including the master), any element can be used in multiple locations and in multiple trees. When I add a child to any element in the tree, I want to either automatically build the secondary structure for each instance of the "master" element or at least advertise the situation to the user and allow them to manually generate the data required for the secondary trees. Is there any pattern which might apply to this situation? I've been treating it as a view problem, but it turns out to be more complicated than that when you look at the initial generation of the data.

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• iPhone Core Data problem

  - by Junior B.

  This is my first project with Core Data, I followed the Event tutorial provided by Apple that helped me to understand the basic of core data in iPhone. But now, working over my project, I've a problem adding data into my database. When i create an object and set the data, if I try to get it back, the system returns me a strange sequence of characters. This is what i see in log if I try to log it: 2010-05-11 00:16:43.523 FG[2665:207] Package: ‡}00å 2010-05-11 00:16:43.525 FG[2665:207] Package: ‡}00å 2010-05-11 00:16:43.526 FG[2665:207] Package: ‡}00å 2010-05-11 00:16:43.527 FG[2665:207] Package: ‡}00å 2010-05-11 00:16:43.527 FG[2665:207] Package: ‡}00å 2010-05-11 00:16:43.527 FG[2665:207] Items: 5 What kind of problem could be this? Edit: This is the part of the code that generate the error: package = (Package *)[NSEntityDescription insertNewObjectForEntityForName:@"Package" inManagedObjectContext:moc]; theNodes = [doc nodesForXPath:@"//pack" error:&error]; for (CXMLElement *theElement in theNodes) { // Create a counter variable as type "int" int counter; // Loop through the children of the current node for(counter = 0; counter < [theElement childCount]; counter++) { if([[[theElement childAtIndex:counter] name] isEqualToString: @"id"]) [package setIdPackage:[[theElement childAtIndex:counter] stringValue]]; if([[[theElement childAtIndex:counter] name] isEqualToString: @"title"]) [package setPackageTitle:[[theElement childAtIndex:counter] stringValue]]; if([[[theElement childAtIndex:counter] name] isEqualToString: @"category"]) [package setCategory:[[theElement childAtIndex:counter] stringValue]]; if([[[theElement childAtIndex:counter] name] isEqualToString: @"lang"]) [package setLang:[[theElement childAtIndex:counter] stringValue]]; if([[[theElement childAtIndex:counter] name] isEqualToString: @"number"]) { NSNumberFormatter * f = [[NSNumberFormatter alloc] init]; [f setNumberStyle:NSNumberFormatterDecimalStyle]; NSNumber * myNumber = [f numberFromString:[[theElement childAtIndex:counter] stringValue]]; [f release]; [package setNumber:myNumber]; } } } NSLog([NSString stringWithFormat:@"=== %s ===\nID: %s\nCategory: %s\nLanguage: %s",[package packageTitle], [package idPackage] ,[package category],[package lang]]);

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• Core Data, Bindings, value transformers : crash when saving

  - by Gael

  Hi, I am trying to store a PNG image in a core data store backed by an sqlite database. Since I intend to use this database on an iPhone I can't store NSImage objects directly. I wanted to use bindings and an NSValueTransformer subclass to handle the transcoding from the NSImage (obtained by an Image well on my GUI) to an NSData containing the PNG binary representation of the image. I wrote the following code for the ValueTransformer : + (Class)transformedValueClass { return [NSImage class]; } + (BOOL)allowsReverseTransformation { return YES; } - (id)transformedValue:(id)value { if (value == nil) return nil; return [[[NSImage alloc] initWithData:value] autorelease]; } - (id)reverseTransformedValue:(id)value { if (value == nil) return nil; if(![value isKindOfClass:[NSImage class]]) { NSLog(@"Type mismatch. Expecting NSImage"); } NSBitmapImageRep *bits = [[value representations] objectAtIndex: 0]; NSData *data = [bits representationUsingType:NSPNGFileType properties:nil]; return data; } The model has a transformable property configured with this NSValueTransformer. In Interface Builder a table column and an image well are both bound to this property and both have the proper value transformer name (an image dropped in the image well shows up in the table column). The transformer is registered and called every time an image is added or a row is reloaded (checked with NSLog() calls). The problem arises when I am trying to save the managed objects. The console output shows the error message : [NSImage length]: unrecognized selector sent to instance 0x1004933a0 It seems like core data is using the value transformer to obtain the NSImage back from the NSData and then tries to save the NSImage instead of the NSData. There are probably workarounds such as the one presented in this post but I would really like to understand why my approach is flawn. Thanks in advance for your ideas and explanations.

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• Generic dataset handling library

  - by Pep.

  Hello, I want to build a generic Perl module for handling and analysing biomedical character separated datasets and which can, most certain, be used on any kind of datasets that contain a mixture of categorical (A,B,C,..) and continuous (1.2,3,881..) and identifier (XXX1,XXX2...). The plan is to have people initialize the module and then use some arguments to point to the data file(s), the place were the analysis reports should be placed and the structure of the data. By structure of data I mean which variable is in which place and its name/type. And this is where I need some enlightenment. I am baffled how to do this in a clean way. Obviously, having people create a simple schema file, be it XML or some other format would be the cleanest but maybe not all people enjoy doing something like this. The solutions I can think of are: Create a configuration file in XML or similar and with a prespecified format. Pass the information during initialization of the module. Use the first row of the data as headers and try to guess types (ouch) Surely there must be a "canonical" way of doing this that is also usable and efficient. Thanks p.

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