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  • How to handle Many-To-Many In Grails without belongsTo?

    - by nute
    I need to create a many-to-many relationship in Grails. I have a "Question" domain and a "Tag" domain. A Question can have 0 or more tags. A Tag can have 0 or more Questions. If I put a "hasMany" on each sides, it gives me an error saying I need a "belongTo" somewhere. However, adding a belongsTo means that the owner must exist... Like I said, a Tag could have 0 questions, and a Question could have 0 tags. There is no concept of an owner, it's a many-to-many! What am I supposed to do?

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  • Is a full list returned first and then filtered when using linq to sql to filter data from a databas

    - by RJ
    This is probably a very simple question that I am working through in an MVC project. Here's an example of what I am talking about. I have an rdml file linked to a database with a table called Users that has 500,000 rows. But I only want to find the Users who were entered on 5/7/2010. So let's say I do this in my UserRepository: from u in db.GetUsers() where u.CreatedDate = "5/7/2010" select u (doing this from memory so don't kill me if my syntax is a little off, it's the concept I am looking for) Does this statement first return all 500,000 rows and then filter it or does it only bring back the filtered list?

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  • What are the differences between MVP, Presentation Model, MVVM and MVC?

    - by Nicholas
    I have a pretty good idea how each of these patterns work some of the minor differences between them, but are they really all that different from each other? It seems to me that the Presenter, Presentation Model, ViewModel and Controller are essentially the same concept. Why couldn't I classify all of these concepts as controllers? I feel like it might simplify the entire idea a great deal. Can anyone give a clear description of their differences? I want to clarify that I do understand how the patterns work, and have implemented most of them in one technology or another. What I am really looking for is someone's experience with one of these patterns, and why they would not consider their ViewModel a controller for instance.

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  • Significance of date 02/31/2157?

    - by dpatchery
    I work in a large scale IT support environment. Twice now we have seen an invalid date of 02/31/2157 being inserted in an Oracle DATE column. So far I have not been able to reproduce this problem, but it appears to be happening occasionally when a user attempts to save '00/00/0000' into the column. I believe the value is originating from a PowerBuilder DataWindow update. The application uses myriad libraries for all sorts of technologies, so this question may be a bit vague, but... Has anyone seen the date 02/31/2157 in some established library that Oracle could be defaulting to when some other invalid date is entered? Perhaps an end-of-time concept analogous to the beginning-of-time date of 1/1/1970?

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  • What are good uses for Python3's "Function Annotations"

    - by agscala
    Function Annotations: PEP-3107 I ran across a snippet of code demonstrating Python3's function annotations. The concept is simple but I can't think of why these were implemented in Python3 or any good uses for them. Perhaps SO can enlighten me? How it works: def foo(a: 'x', b: 5 + 6, c: list) -> max(2, 9): ... function body ... Everything following the colon after an argument is an 'annotation', and the information following the -> is an annotation for the function's return value. foo.func_annotations would return a dictionary: {'a': 'x', 'b': 11, 'c': list, 'return': 9} What's the significance of having this available?

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  • Where's the definitive resource online about how to carry out Agile development?

    - by jdk
    I want to start Agile practices in a team. I'm assuming the information is available for free online about how to specifically carry it out. Online I can locate the manifesto, the alliances and corporations involved but where is the actual central guide or root instruction set about how to do it? (Maybe the practices themselves are more ethereal or subjective than I expect and it's found in multiple places?) Edit to summarize solutions: Agile is a concept so that's what's to be found online about it. However specific processes or methods of Agile development have been created like Scrum and Extreme programming to provide concrete solutions to teams who want to adopt Agile and reap its proposed benefits. Find the shoe (or method) that fits best. Maybe create it. If looking for solutions online to implement Agile development in your organization or for your project, seek out the specific methods too and decide among them.

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  • What is this project/compilation source structure?

    - by Werner
    Hi, I am working on some project my boss sent to me. After unzipping, this is the structure of the files: executable_file config.mk doc include lib Makefile sources I have only worked with "usual" Makefile projects. But I do not undersatnd the meaning of config.mk here. Do you know which kind of "build" structure (what is the right name for this concept?) is it, and where can i find more information about this? I need to modify it, so it compiles in another hardware, so I do not know where I sohuld work on. Thanks

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  • UDP + total order, non-reliable

    - by disown
    I'm trying to find a version of UDP which just alleviates the restriction of a maximum size of the message sent. I don't care about reliability or partial retransmission, if all chunks arrive I want the message to be assembled from the chunks in sending order and delivered to the listening app. If one or more chunks are missing I would just like to discard the message. The goal is to have a low-latency notification mechanism about real time data, but with the added support for bigger messages than what would fit in an IP datagram. I would like the protocol to be one way only, and not have long connection setup times. An optional feature to be able to respond to a received message wouldn't hurt (a concept of an unreliable connection), but is not necessary.

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  • Unable to get set intersection to work

    - by chavanak
    Sorry for the double post, I will update this question if I can't get things to work :) I am trying to compare two files. I will list the two file content: File 1 File 2 "d.complex.1" "d.complex.1" 1 4 5 5 48 47 65 21 d.complex.10 d.complex.10 46 6 21 46 109 121 192 192 TI am trying to compare the contents of the two file but not in a trivial way. I will explain what I want with an example. If you observe the file content I have typed above, the d.complex.1 of file_1 has "5" similar to d.complex.1 in file_2; the same d.complex.1 in file_1 has nothing similar to d.complex.10 in file_2. What I am trying to do is just to print out those d.complex. which has nothing in similar with the other d.complex. Consider the d.complex. as a heading if you want. But all I am trying is compare the numbers below each d.complex. and if nothing matches, I want that particular d.complex. from both files to be printed. If even one number is present in both d.complex. of both files, I want it to be rejected. My Code: The method I chose to achieve this was to use sets and then do a difference. Code I wrote was: first_complex=open( "file1.txt", "r" ) first_complex_lines=first_complex.readlines() first_complex_lines=map( string.strip, first_complex_lines ) first_complex.close() second_complex=open( "file2.txt", "r" ) second_complex_lines=second_complex.readlines() second_complex_lines=map( string.strip, second_complex_lines ) second_complex.close() list_1=[] list_2=[] res_1=[] for line in first_complex_lines: if line.startswith( "d.complex" ): res_1.append( [] ) res_1[-1].append( line ) res_2=[] for line in second_complex_lines: if line.startswith( "d.complex" ): res_2.append( [] ) res_2[-1].append( line ) h=len( res_1 ) k=len( res_2 ) for i in res_1: for j in res_2: print i[0] print j[0] target_set=set ( i ) target_set_1=set( j ) for s in target_set: if s not in target_set_1: if s[0] != "d": print s The above code is giving an output like this (just an example): d.complex.1.dssp d.complex.1.dssp 1 48 65 d.complex.1.dssp d.complex.10.dssp 46 21 109 What I would like to have is: d.complex.1 d.complex.1 (name from file2) d.complex.1 d.complex.10 (name from file2) I am sorry for confusing you guys, but this is all that is required. I am so new to python so my concept above might be flawed. Also I have never used sets before :(. Can someone give me a hand here?

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  • How to use TestAndSet() for solving the critical section problem?

    - by Dan Mantyla
    I'm studying for an exam and I'm having difficulty with a concept. This is the pseudo code I am given: int mutex = 0; do { while (TestAndSet(&mutex)); // critical section mutiex = 0; // remainder section } while (TRUE); My instructor says that only two of the three necessary conditions (mutual exclusion, progress, and bounded waiting) are met with this code, but I don't understand which one isn't being met...?? How should the code be modified to support the missing condition to solve the critical region problem? Thanks in advance for any insight!

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  • in .net, what programming model would be good for prototyping, but then reusable for production (for

    - by Greg
    Hi, In .NET land what would be a good approach for quick prototyping of a concept (i.e. development just on my PC) that could then be extended out to product (users across LAN/WAN), BUT in a fashion that the model/business logic code and data access layer code can be used as is? One thought for example I had as to do: (a) WinForms with business logic and Entity Framework layer to SQL Server Express on my PC, then (b) Go then to ASP.net (using the business logic / data library) with SQL Server/IIS Any comments? Other suggestions?

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  • How to organise a many to many relationship in MongoDB

    - by Gareth Elms
    I have two tables/collections; Users and Groups. A user can be a member of any number of groups and a user can also be an owner of any number of groups. In a relational database I'd probably have a third table called UserGroups with a UserID column, a GroupID column and an IsOwner column. I'm using MongoDB and I'm sure there is a different approach for this kind of relationship in a document database. Should I embed the list of groups and groups-as-owner inside the Users table as two arrays of ObjectIDs? Should I also store the list of members and owners in the Groups table as two arrays, effectively mirroring the relationship causing a duplication of relationship information? Or is a bridging UserGroups table a legitimate concept in document databases for many to many relationships? Thanks

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  • Inconsistent Routing Results in MVC

    - by HapiDjus
    Seems I'm still missing something to the MVC routing concept. I have a route that follows nearly the same pattern as another route in an area but for what ever reason I get a 404 every time I attempt to run it. I've tried to use Phil Haack's Route Tester DLL and according to that it hits the correct route (matched route comes out to common/itemhistory/{contentid}). When I try to run it for real, it blows up. I'm trying to map a call to a JsonResult by passing a Guid. I've had success with other routes working fine (common is an area in my site). What could I be doing wrong? context.MapRoute( "ItemHistory", "common/itemhistory/{contentid}", new { controller = "common", action = "GetItemHistory" }, new { contentid = @"^(\{){0,1}[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}(\}){0,1}$" } ); context.MapRoute( "Common_default", "common/{action}", new { controller="common", action = "Index" } );

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  • DRY vs Security and Maintainability with MVC and View Models

    - by Mystere Man
    I like to strive for DRY, and obviously it's not always possible. However, I have to scratch my head over a concept that seems pretty common in MVC, that of the "View Model". The View Model is designed to only pass the minimum amount of information to the view, for both security, maintainability, and testing concerns. I get that. It makes sense. However, from a DRY perspective, a View Model is simply duplicating data you already have. The View Model may be temporary, and used only as a DTO, but you're basically maintaing two different versions of the same model which seems to violate the DRY principal. Do View Models violate DRY? Are they a necessary evil? Do they do more good than bad?

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  • Capturing system command output as a string

    - by dreeves
    Perl and PHP do this with backticks. For example: $output = `ls`; This code returns a directory listing into the variable $output. A similar function, system("ls"), returns the operating system return code for the given command. I'm talking about a variant that returns whatever the command prints to stdout. (There are better ways to get the list of files in a directory; the example code is an example of this concept.) How do other languages do this? Is there a canonical name for this function? (I'm going with "backtick"; though maybe I could coin "syslurp".)

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  • How to Delete Duplicate Rows in SQL 2000?

    - by Mikecancook
    I thought I had this figured out but it turns out I'm just deleting the first record. The following returns the duplicate rows. All have a count of 2. I just want to delete the first one for each duplicate record. select scorestudentid, scoreadvisor, scorecorrect, count(*) from scores where scoretestid = 3284 group by scorestudentid, scoreadvisor, scorecorrect having count(scorestudentid) > 1 Which returns: scorestudentid scoreadvisor scorecorrect no column name 13033719 28059 3.0 2 13033777 28086 3.0 2 13033826 28147 3.0 2 13033960 28023 3.0 2 So I put this together thinking it would work: set rowcount 1 delete from scores where scoretestid = 3284 and scorestudentid in ( select scorestudentid from scores where scoretestid = 3284 group by scorestudentid having count(scorestudentid) > 1) It really seems like it should be a simple concept but I'm not getting it.

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  • PHP OOP: Unique method per argument type?

    - by sunwukung
    I'm writing a little homebrew ORM (academic interest). I'm trying to adhere to the TDD concept as a training exercise, and as part of that exercise I'm writing documentation for the API as I develop the class. Case in point - I'm working on a classic "getCollection" type mapper class. I want it to be able to retrieve collections of asset X (let's say blog posts) for a specific user, and also collections based on an arbitrary array of numeric values. So - you might have a method like any one of these $User = $UserMapper->load(1); $ArticleCollection = $ArticleMapper->getCollection(range(10,20)); $ArticleCollection = $ArticleMapper->getCollection($User); $ArticleCollection = $ArticleMapper->getCollection($User->getId()); So, in writing the documentation for the getCollection method - I want to declare the @param variable in the Docblock. Is it better to have a unique method for each argument type, or is it acceptable to have a method that delegates to the correct internal method/class based on argument type?

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  • What's the deal with all of the abstract stuff?

    - by JustVenting
    I see a lot of talk about MVVM, MVC, Design Patterns etc... You know, some guy has a blog, and he spent the last six months learning about one these things and desiging a program centered around that concept and then he goes on and on about it like its better than sliced bread. I read all of this crap and I wonder, whatever happened to simple logical programming? Not self-absorbed huge frameworks of design patterns and mvc and whatever else you can think of... just simple linear programming, perhaps a few classes to encapsulate things here and there.

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  • using helper methods in a view in rails 3

    - by Frida777
    Hello everyone, there is something that is disturbing me a bit about rails 3. i am trying to upgrade my application from rails 2 to rails 3. i followed all the steps necessary to do and things were working well for me till now except one thing: i have a helper method that is defined differently in different helpers, for example it is defined in the application_helper in one way and the same method defined in a different way in the homepage_helper, and defined differently in another helper, let's say video_helper, in addition to that, it is used in a shared view that is used throughout the application, now if i am in the homepage, i want this function to get called from the homepage_helper and if i am in the video page, the function must be called from the video_helper, based on the concept of convention in rails, this worked perfectly in rails 2 but in rails 3, the function is always called from the last helper, alphabetically ordered, that is in the example, video_helper. How can i fix this? Kindly advice. Appreciate all the help.

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  • Is this the correct why of speaking to a "Content Manager" Class?

    - by DeanMc
    I am creating a silverlight site. I am currently breaking out my ideas into pieces of functionality. One of the idea's I have is the concept of a content manager. This is essentially a UI control with 4 regions. Top, Bottom, Right & Left. I also have a collection of objects that are considered "Menu Items". These are controls that function as a way to navigate around, similar to links. The idea I have is to implement an IMenuItem interface. Among the standard pieces of information (Text, PageReference, etc) I was also going to hold a reference to the content manager. My idea behind this thinking is that I can pass the PageReference to a property on the ContentManager and then call a method which knows how to update the content manager accordingly. Is this the best way of implementing this or is their some sort of pattern for it?

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  • Learning C++ from AS3

    - by grey
    I'm a decent AS3 programmer. I work in games, and that is my reason for programming. While there is much I can accomplish with Adobe AIR, my understanding at this point is that learning C++ is probably a good direction to take. I would learn a lot of valuable lower level programming if I needed it down the road, and I would have an easier time learning other C oriented languages. I see a lot of information for people looking to learn AS3 who know C++, but not the other way around. Why C++? Cross platform compatibility is important to me, so I'm not particularly interested in C# or Objective-C at this junction. I'm also aware of HaXe, and while I love the concept, after doing some research I'm worried about investing a lot of time into something so recent with limited learning resources and documentation. I'm looking for advice and resources (books, articles) related to this topic. Thanks in advance!

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  • basic database design table on rails

    - by runcode
    I am confuse on a concept. I am doing this on rails. Is that Entity set equal to a table in the database? Is that Relationship set equal to a table in the database? Let say we have Entity set "USER" and Entity set "POST" and Entity set "COMMENT" User- can post many posts and comments as they want Post- belong to users Comments-belong to posts ,users, so comment is weak entity. SCHEMA ====== USER -id -name POST -id -user_id(FK) -comment_id (FK) COMMENT -id -user_id (FK) -post_id (FK) so USER,POST,COMMENT are tables I think. And what else is a table? And do I need a table for the relationship??

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  • Correct use of a "for...in" loop in javascript?

    - by jnkrois
    Hello everybody, before I ask my question I wanted to let everybody know that I appreciate the fact that there's always somebody out there willing to help, and on my end I'll try to give back to the community as much as I can. Thanks Now, I would like to get some pointers as to how to properly take advantage of the "for...in" loop in JavaScript, I already did some research and tried a couple things but it is still not clear to me how to properly use it. Let's say I have a random number of "select" tags in an HTML form, and I don't require the user to select an option for all of them, they can leave some untouched if they want. However I need to know if they selected none or at least one. The way I'm trying to find out if the user selected any of them is by using the "for...in" loop. For example: var allSelected = $("select option:selected"); var totalSelected = $("select option:selected").length; The first variable produces an array of all the selected options. The second variable tells me how many selected options I have in the form (select tags could be more than one and it changes every time). Now, in order to see if any has been selected I loop through each element (selected option), and retrieve the "value" attribute. The default "option" tag has a value="0", so if any selected option returns a value greater than 0, I know at least one option has been selected, however it does not have to be in order, this is my loop so far: for(var i = 0; i < totalSelected; i++){ var eachOption = $(allSelected[i]).val(); var defaultValue = 0; if(eachOption == defaultValue){ ...redirect to another page }else if(eachOption > defaultValue){ ... I display an alert } } My problem here is that as soon as the "if" matches a 0 value, it sends the user to the next page without testing the rest of the elements in the array, and the user could have selected the second or third options. What I really want to do is check all the elements in the array and then take the next action, in my mind this is how I could do it, but I'm not getting it right: var randomValue = 25; for(randomValue in allSelected){ var found = true; var notFound = false if(found){ display an alert }else{ redirect to next page } } This loop or the logic I'm using are flawed (I'm pretty sure), what I want to do is test all the elements in the array against a single variable and take the next action accordingly. I hope this makes some sense to you guys, any help would be appreciated. Thanks, JC

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  • is there some lightweight tecnique for adding type safety to identifier properties?

    - by shoren
    After using C++ I got used to the concept of Identifier which can be used with a class for the type, provides type safety and has no runtime overhead (the actual size is the size of the primitive). I want to do something like that, so I will not make mistakes like: personDao.find(book.getId());//I want compilation to fail personDao.find(book.getOwnerId());//I want compilation to succeed Possible solutuions that I don't like: For every entity have an entity id class wrapping the id primitive. I don't like the code bloat. Create a generic Identifier class. Code like this will not compile: void foo(Identifier book); void foo(Identifier person); Does anyone know of a better way? Is there a library with a utility such as this? Is implementing this an overkill? And the best of all, can this be done in Java without the object overhead like in C++?

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  • Reading Matrices in MATLAB and assigning coordinates to the entries

    - by Michael Schofield
    Hi, I'm a bit new to MATLAB. Basically, I have a 25x25 Matrix, complete with various random entries ranging from 0 to 3. I need to write a program that reads this matrix, and assigns x-y coordinates to the entries, so that when I ask for an input of a particular x-y coordinate which has, say an entry of 3, then it will result in an error. I'm a bit overwhelmed - but I understand the general concept of what I'm supposed to be finding. I'm wondering if I should use a plot instead to help me.

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