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• What types of objects should the ViewModel reference in the MVVM pattern?

  - by Blanthor

  I've seen quite a few examples of MVVM. I can see that the View should reference the ViewModel. I've seen recently an example of a ViewModel referencing a View, which seems wrong to me, as it would result in tighter coupling. Given that ViewModel is often described as an intermediary between the View and the Model, is there more to the ViewModel than a facade to domain objects? I hope I used the term "facade" correctly here.

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• Recommendation for tool/framework that follows the naked objects pattern?

  - by Marcus Munzert

  I am searching for a tool/framework that follows the naked objects pattern and is written in Java. I know about tools like for instance JMatter, Naked Objects and Domain Object Explorer. That's not exactly what I am searching for, though. Open source would be great, but doesn't need to be. My intention is to use that tool/framework for the purpose of model-driven software development to do the modeling part. Ideally, such a tool/framework would provide the option to use JPA to store/load objects.

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• pattern to transfer search model to dao

  - by zeroed

  We have a dao as a project (jar file). Clients use its interfaces and factories to operate with database. Using standard CRUD operations, dao allows you to search an entity by some search criteria. What is the best way to represent this criteria? Is transfer object appropriate pattern in this situation? How should client create SearchModel instance? Please, share. Regards.

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• What is MVC and what are the advantages of it?

  - by Teifion

  I found What are mvp and mvc and what is the difference but it didn't really answer this question. I've recently started using MVC because it's part of the framework that myself and my work-partner are going to use. We chose it because it looked easy and separated process from display, are there advantages besides this that we don't know about and could be missing out on? Pros Display and Processing are seperated Cons None so far

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• How do you determine how coarse or fine-grained a 'responsibility' should be when using the single r

  - by Mark Rogers

  In the SRP, a 'responsibility' is usually described as 'a reason to change', so that each class (or object?) should have only one reason someone should have to go in there and change it. But if you take this to the extreme fine-grain you could say that an object adding two numbers together is a responsibility and a possible reason to change. Therefore the object should contain no other logic, because it would produce another reason for change. I'm curious if there is anyone out there that has any strategies for 'scoping', the single-responsibility principle that's slightly less objective?

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• How to find the entity with the greatest primary key?

  - by simpatico

  I've an entity LearningUnit that has an int primary key. Actually, it has nothing more. Entity Concept has the following relationship with it: @ManyToOne @Size(min=1,max=7) private LearningUnit learningUnit; In a constructor of Concept I need to retrieve the LearningUnit with the greatest primary key. If no LearningUnit exists yet I instantiate one. I then set this.learningUnit to the retrieved/instantied. Finally, I call the empty constructor of Concept in a try-catch block, to have the entitymanager do the cardinality check. If an exception is thrown (I expect one in the case that already another 7 Concepts are referring to the same LearningUnit. In that case, I case instantiate a new LearningUnit with a new greater primary key. Please, also point out, if any, clear pitfalls in my outlined algorithm above.

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• What's the simplest way to make a scrollable list of controls with labels?

  - by Jon Cage

  Using C++/CLI and Windows Forms, I'm trying to make a simple scrollable list of labelled text controls as a way of displaying some data fields. I'm having trouble making a TableLayoutPanel scrollable - every combination of properties I've tried seems to result in some really peculiar side effects. So I have two questions: Is this the best way to do it. If it is a reasonable approach, what magic combination of settings should I apply to the table layout panel to make it play ball?

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• Compressing a database to a single file?

  - by Assimilater

  Hi all. In my contact manager program I have been storing information by reading and writing comma delimited files for each individual contact, and storing notes in a file for each note, and I'm wondering how I could go about shrinking them all into one file effectively. I have attempted using data entry tools in the visual studio toolbox and template class, though I have never quite figured out how to use them. What would be especially convenient is if I could store data as data type IOwner (a class I created) as opposed to strings. I'd also need to figure out how to tell the program what to do when a file is opened (I've noticed in the properties how to associate a file type with the program though am not sure how to tell it what to do when it's opened). Edit: How about rephrasing the question: I have a class IContact with various properties some of them being lists of other class objects. I have a public list of IContact. Can I write Contacts as List(Of IContact) to a file as opposed to a bunch of strings? Second part of the question: I have associated .cms files with my program. But if a user opens the file, what code should the program run through in an attempt to deal with the file? This file is going to contain data that the program needs to read, how do I tell it to read a file when the program is opened vicariously because the file was opened? Does this make the question clearer?

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• Fastest way to do a weighted tag search in SQL Server

  - by Hasan Khan

  My table is as follows ObjectID bigint Tag nvarchar(50) Weight float Type tinyint I want to get search for all objects that has tags 'big' or 'large' I want the objectid in order of sum of weights (so objects having both the tags will be on top) select objectid, row_number() over (order by sum(weight) desc) as rowid from tags where tag in ('big', 'large') and type=0 group by objectid the reason for row_number() is that i want paging over results. The query in its current form is very slow, takes a minute to execute over 16 million tags. What should I do to make it faster? I have a non clustered index (objectid, tag, type) Any suggestions?

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• How to evade writing a lot of repetitive code when mapping?

  - by JPCF

  I have a data access layer (DAL) using Entity Framework, and I want to use Automapper to communicate with upper layers. I will have to map data transfer objects (DTOs) to entities as the first operation on every method, process my inputs, then proceed to map from entities to DTOs. What would you do to skip writing this code? As an example, see this: //This is a common method in my DAL public CarDTO getCarByOwnerAndCreditStatus(OwnerDTO ownerDto, CreditDto creditDto) { //I want to automatize this code on all methods similar to this Mapper.CreateMap<OwnerDTO,Owner>(); Mapper.CreateMap<CreditDTO,Credit>(); Owner owner = Mapper.map(ownerDto); Owner credit = Mapper.map(creditDto) //... Some code processing the mapped DTOs //I want to automatize this code on all methods similar to this Mapper.CreateMap<Car,CarDTO>(); Car car = Mapper.map(ownedCar); return car; }

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• Implementing a 'many-to-many' database

  - by Raven Dreamer

  Greetings, stack*overflow* In my database, I already have one table, 'contacts' that contains records of individual people. I also have several other tables in my database which represent "skill sets" that contain records denoting a particular skill. 1) Am I correct in plotting this as a "many-to-many" relationship? (each contact can have multiple skill sets, and each skill set can belong to multiple contacts) 2) I'm new to databases -- do I want to link the tables? 3) Is there a way to implement this in my program (C# + windows forms) such that for any given record in the 'contacts' table, either the names of all associated 'skill set' tables or all the 'skill' records associated with the 'contact' record could be retrieved? (Database is located on SQL Server Express 2008)

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• Seeking free ODBC database optimization tool for non-experts

  - by mawg

  I'm a database n00b and am reading as many books as I can. I have been given responsibility for an ODBC tool where the databases were designed by a hardware engineer with some VB experience - which made him a s/w guru in the small firm at that time. Things are running slowly and I suspect that the db could have been designed better. I hope to learn enough to use Explain/Describe, etc maybe add some indices, but, in the meantime, is there any free for commercial use tool which can examine an ODBC database and suggest improvements. I'm just talking about db schema here, but maybe I should also be looking at optimizing Selects with Joins? Is there a tool for that? ODBC compliant.

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• user height and weight in sql

  - by Samuel

  We are planning to capture a user's height and weight and am looking for ideas on representing them in sql. I have the following questions in mind weight can be expressed in kilograms and grams and height in meters and centimeters, so should I capture them as a BigDecimal with an appropriate precision and scale or capture them as vanilla strings and do the manipulation in the user interface. Note: I am planning to capture the kilograms and grams separately in the user interface. should the metric of measurement be part of the sql (i.e. the end user might want to view this information in pounds, inches according to his preference) OR Should I just support kilograms / meters in the database and do the conversion while showing this in the user interface

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• Would this constructor be acceptable practice?

  - by Robb

  Let's assume I have a c++ class that have properly implemented a copy constructor and an overloaded = operator. By properly implemented I mean they are working and perform a deep copy: Class1::Class1(const Class1 &class1) { // Perform copy } Class1& Class1::operator=(const Class1 *class1) { // perform copy return *this; } Now lets say I have this constructor as well: Class1::Class1(Class1 *class1) { *this = *class1; } My question is would the above constructor be acceptable practice? This is code that i've inherited and maintaining.

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• What is a good architecture for a Lift-JPA application?

  - by egervari

  I was wondering what is the best practice for a JPA model in Lift? I noticed that in the jpa demo application, there is just a Model object that is like a super object that does everything. I don't think this can be the most scalable approach, no? Is it is wise to still do the DAO pattern in Lift? For example, there's some code that looks a tad bloated and could be simplified across all model objects: Model.remove(Model.getReference(classOf[Author], someId)) Could be: AuthorDao.remove(someId) I'd appreciate any tips for setting up something that will work with the way Lift wants to work and is also easy to organize and maintain. Preferably from someone who has actually used JPA on a medium to large Lift site rather than just postulating what Spring does (we know how to do that) ;) The first phase of development will be around 30-40 tables, and will eventually get to over 100... we need a scalable, neat approach.

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• Pattern for iPhone background loading during init?

  - by Rob S.

  Hi everyone, I'm currently kicking off a background thread to do some REST queries in my app delegate's didFinishLaunchingWithOptions. This thread creates some objects and populates the model as the rest of the app continues to load (because I don't block, and didFinishLaunchingWithOptions returns YES). I also put up a loading UIViewController 'on top' of the main view that I tear down after the background initialization is complete. My problem is that I need to notify the first view (call it the Home view) that the model is ready, and that it should populate itself. The trick is that the background download could have finished before Home.viewDidAppear is called, or any of the other Home.initX methods. I'm having difficulty synchronizing all of this and I've thought about it long enough that it feels like I'm barking up the wrong tree. Are there any patterns here for this sort of thing? I'm sure other apps start by performing lengthy operations with loading screens :) Thanks!

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• singleton class in java API

  - by JavaUser

  What are the best examples of Singleton Pattern in Java API? Is Runtime class a singleton?

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• How would I implement separate databases for reading and writing operations?

  - by Matt

  I am interested in implementing an architecture that has two databases one for read operations and the other for writes. I have never implemented something like this and have always built single database, highly normalised systems so I am not quite sure where to begin. I have a few parts to this question. 1. What would be a good resource to find out more about this achitecture? 2. Is it just a question of replicating between two identical schemas, or would your schemas differ depending on the operations, would normalisation vary too? 3. How do you insure that data written to one database is immediately available for reading from the second? Any further help, tips, resources would be appreciated. Thanks.

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• Table with unequal rows in XUL layout

  - by Michael

  Trying to get something similar for Firefox extension using XUL. The most difficult part is the grid with unequal number of rows. I tried <grid> but it didn't work well. Also don't want to use HTML inside of XUL. Any ideas how to build such table?

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• Define "Validation in the Model"

  - by sunwukung

  There have been a couple of discussions regarding the location of user input validation: http://stackoverflow.com/questions/659950/should-validation-be-done-in-form-objects-or-the-model http://stackoverflow.com/questions/134388/where-do-you-do-your-validation-model-controller-or-view These discussions were quite old, so I wanted to ask the question again to see if anyone had any fresh input. If not, I apologise in advance. If you come from the Validation in the Model camp - does Model mean OOP representation of data (i.e. Active Record/Data Mapper) as "Entity" (to borrow the DDD terminology) - in which case you would, I assume, want all Model classes to inherit common validation constraints. Or can these rules simply be part of a Service in the Model - i.e. a Validation service? For example, could you consider Zend_Form and it's validation classes part of the Model? The concept of a Domain Model does not appear to be limited to Entities, and so validation may not necessarily need to be confined to this Entities. It seems that you would require a lot of potentially superfluous handing of values and responses back and forth between forms and "Entities" - and in some instances you may not persist the data recieved from user input, or recieve it from user input at all.

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• What Features do you Consider Brilliantly implemented in C++

  - by John

  Following features to remove from c++ and desired features for c++ I thought why not complete the trio... what features are you happy about in C++ and don't want to change at all? What features are elegantly and brilliantly implemented and still look better than other more modern languages

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• How to create a better tables Structure.

  - by user160820

  For my website i have tables Category :: id | name Product :: id | name | categoryid Now each category may have different sizes, for that I have also created a table Size :: id | name | categoryid | price Now the problem is that each category has also different ingredients that customer can choose to add to his purchased product. And these ingredients have different prices for different sizes. For that I also have a table like Ingredient :: id | name | sizeid | categoryid | price I am not sure if this Structure really normalized is. Can someone please help me to optimize this structure and which indexed do i need for this Structure?

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• What is the right way to do flexible columns in database?

  - by Timmy

  Im storing columns in database with users able to add and remove columns, with fake columns. How do I implement this efficiently?

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• ASP.NET MVC Filters: How to set Viewdata for Dropdown based on action parameter

  - by CRice

  Hi, Im loading an entity 'Member' from its id in route data. [ListItemsForMembershipType(true)] public ActionResult Edit(Member someMember) {...} The attribute on the action loads the membership type list items for a dropdown box and sticks it in viewdata. This is fine for add forms, and search forms (it gets all active items) but I need the attribute to execute BASED ON THE VALUE someMember.MembershipTypeId, because its current value must always be present when loading the item (i.e. all active items, plus the one from the loaded record). So the question is, what is the standard pattern for this? How can my attribute accept the value or should I be loading the viewdata for the drop down in a controller supertype or during model binding or something else? It is in an attribute now because the code to set the viewdata would otherwise be duplicated in each usage in each action.

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• Is there a prefered way to specify a text column in SQLite?

  - by JannieT

  Since the SQLite engine will not truncate the data you store in a text column, is there any advantage in being specific with column sizes when you define your schema? Would anyone prefer this: CREATE TABLE contact( id INTEGER PRIMARY KEY, name VARCHAR(45), title VARCHAR(10) ); over this: CREATE TABLE contact( id INTEGER PRIMARY KEY, name TEXT, title TEXT ); Why? Are there advantages to not being specific?

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