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• Mixing LINQ to SQL with properties of objects in a generic list

  - by BPotocki

  I am trying to accomplish something like this query: var query = from a in DatabaseTable where listOfObjects.Any(x => x.Id == a.Id) select a; Basically, I want to filter the results where a.Id equals a property of one of the objects in the generic list "listOfObjects". I'm getting the error "Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator." Any ideas on how to filter this in an easily readable way using "contains" or another method? Thanks in advance.

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• how to convert big-endian numbers to native numbers delphi

  - by steve0

  hi all i want to know how to convert big endian numbers to native numbers in delphi i am porting some c++ code in that i came accross this part unsigned long blockLength = *blockLengthPtr++ << 24; blockLength |= *blockLengthPtr++ << 16; blockLength |= *blockLengthPtr++ << 8; blockLength |= *blockLengthPtr; unsigned long dataLength = *dataLengthPtr++ << 24; dataLength |= *dataLengthPtr++ << 16; dataLength |= *dataLengthPtr++ << 8; dataLength |= *dataLengthPtr; i am not familiar with c++ ,so i didnt understand what those operators doing can any one help ? regards

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• Understanding NoSQL Data Modeling - blog application

  - by Rushabh RajeshKumar Padalia

  I am creating an blogging application in Node.js + MongoDB Database. I have used relational Database like MySQL before but this is my first experience with NoSQL database. So I would like to conform my MongoDB data models before I move further. I have decided my blogDB to have 3 collections post_collection - stores information about that article comment_collection - store information about comments on articles user_info_collection - contains user inforamtion PostDB { _"id" : ObjectID(...), "author": "author_name", "Date": new Date(....), "tag" : ["politics" , "war"], "post_title": "My first Article", "post_content": "Big big article" "likes": 23 "access": "public" } CommentDB { "_id" : Objectid(...), "POST": "My First Article", "comment_by": "User_name", "comment": "MY comments" } UserInfoDB { "_id": ObjectID(...), "user": "User_name", "password": "My_password" } I would appreciate your comments.

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• How to create and Expression tree to do the same as "StartsWith"

  - by Jonathan

  Hi to all. Currently, I have this method to compare two numbers Private Function ETForGreaterThan(ByVal query As IQueryable(Of T), ByVal propertyValue As Object, ByVal propertyInfo As PropertyInfo) As IQueryable(Of T) Dim e As ParameterExpression = Expression.Parameter(GetType(T), "e") Dim m As MemberExpression = Expression.MakeMemberAccess(e, propertyInfo) Dim c As ConstantExpression = Expression.Constant(propertyValue, propertyValue.GetType()) Dim b As BinaryExpression = Expression.GreaterThan(m, c) Dim lambda As Expression(Of Func(Of T, Boolean)) = Expression.Lambda(Of Func(Of T, Boolean))(b, e) Return query.Where(lambda) End Function It works fine and is consumed in this way query = ETForGreaterThan(query, Value, propertyInfo) As you can see, I give it an IQueryable collection and it add a where clause to it, base on a property and a value. Y can construct Lessthan, LessOrEqualThan etc equivalents as Expression has this operators predefined. ¿How can I transform this code to do the same with strings? Expression don't give me a predefined operator like "contains" or "startwith" and I'm really noob with Expression trees. Thanks, and please Post your answer in C#/VB. Choose the one that make you feel more confortable.

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• Storing Data as XML BLOB

  - by NBrowne

  Hi, At the moment the team i am working with is looking into the possibility of storing data which is entered by users from a series of input wizard screens as an XML blob in the database. the main reason for this being that i would like to write the input wizard as a component which can be brought into a number of systems without having to bring with it a large table structure. To try to clarify if the wizard has 100 input fields (for example) then if i go with the normal relational db structure then their will be a 1 to 1 relationship so will have 100 columns in database. So to get this working in another system will have to bring the tables,strore procedures etc into the new system. I have a number of reservations about this but i would like peoples opinions?? thanks

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• What is the best solution to replace a new memory allocator in an existing code?

  - by O. Askari

  During the last few days I've gained some information about memory allocators other than the standard malloc(). There are some implementations that seem to be much better than malloc() for applications with many threads. For example it seems that tcmalloc and ptmalloc have better performance. I have a C++ application that uses both malloc and new operators in many places. I thought replacing them with something like ptmalloc may improve its performance. But I wonder how does the new operator act when used in C++ application that runs on Linux? Does it use the standard behavior of malloc or something else? What is the best way to replace the new memory allocator with the old one in the code? Is there any way to override the behavior or new and malloc or do I need to replace all the calls to them one by one?

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• How to call operator<< on "this" in a descendant of std::stringstream?

  - by romkyns

  class mystream : public std::stringstream { public: void write_something() { this << "something"; } }; This results in the following two compile errors on VC++10: error C2297: '<<' : illegal, right operand has type 'const char [10]' error C2296: '<<' : illegal, left operand has type 'mystream *const ' Judging from the second one, this is because what this points at can't be changed, but the << operator does (or at least is declared as if it does). Correct? Is there some other way I can still use the << and >> operators on this?

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• How to return relationships in a custom un-typed dataservice provider

  - by monkey_p

  I have a custom .Net DataService and can't figure out how to return the data for relationships. The data base has 2 tables (Customer, Address). A Customer can have multiple addresses, but each address can only have on customer. I'm using Dictionary<string,object> as my data type. My question, for the following 2 urls how do i return the data. http://localhost/DataService/Customer(1)/Address http://localhost/DataService/Address(1)/Customer For the none relational queries I return a List<Dictionary<string,object>> So I imagined for the relation I should just populate the element with a either a Dictionary<string,object> for the single ones and a List<Dictionary<string,object>> for many relationships. But this just gives me a NullRefferenceException So what am I doing wrong?

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• What features can I use during log in/out

  - by thecoshman

  I know that this question is going to be painfully vague, but here it is any way. I have made an small console application designed to be run on Windows XP Pro computers. It will be run at log in and log out. The command to run this program will be set via GPO and will include command line operators to control what data the program sends. I have used a few built in C# classes to find out information about the computer, which is then sent of to a server as a web request. I need to know which of the following will have issues on a restricted user account on a domain. Enviroment ManagementObjectSearcher ManagmentObjectCollection System.Diagnostics.PerformanceCounter <-- side note, this class dosent seem to accept be saying using System.Diagnostics ComputerInfo WebRequest

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• A better understanding of the relations beetween database tables

  - by Nistor Alexandru

  Hi I am trying to get a better understanding of relational databases and there is something that I keep bumping into and don't understand.Let's take this two tables: In this case Login.ID is the primary key with auto_increment set and Profile.ID_LOGIN is the Foreign KEY.When a user is created and it's username and password is stored in the login database does the ID coresponding to the curesnt username and password get automaticly added into ID_LOGIN or do I have to create an SQL statement to do this? If I have to create a SQL statement how should I aproach adding the ID_LOGIN to make sure I am adding it corectly?

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• Can a variable like 'int' be considered a primitive/fundamental data structure?

  - by Ravi Gupta

  A rough definition of a data structure is that it allows you to store data and apply a set of operations on that data while preserving consistency of data before and after the operation. However some people insist that a primitive variable like 'int' can also be considered as a data structure. I get that part where it allows you to store data but I guess the operation part is missing. Primitive variables don't have operations attached to them. So I feel that unless you have a set of operations defined and attached to it you cannot call it a data structure. 'int' doesn't have any operation attached to it, it can be operated upon with a set of generic operators. Please advise if I got something wrong here.

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• Sorting and displaying a custom QVariant type.

  - by Kranar

  Hello, I have a custom type I'd like to use with QVariant but I don't know how to get the QVariant to display in a table or have it sort in a QSortFilterProxyModel. I register the type with Q_DECLARE_METATYPE and wrote streaming operators registered via qRegisterMetaTypeStreamOperators but for whatever reason when I use the type with a table model, it doesn't display anything and it doesn't sort. I should specify that this custom type can not be modified. It has a copy and default constructor, but I can not go in and modify the source code to get it to work with QVariant. Is there a way of non-intrusively getting the behaviour I'd like?

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• Is there a tool that will show diagrams of my SQL database in real-time?

  - by Rising Star

  I've created some diagrams of SQL tables using the "Reverse Engineer" feature of Microsoft Office Visio. I like being able to visualize my relational databases in this manner. However, what I get is just a static document that I can print, e-mail to colleagues, and click widgets on. Earlier this year, I saw at a demo that the new version of Visual Studio 2010 has a new feature called the "Architect Explorer", which allows developers to view relationships among .net classes on the fly. It has many features for filtering the data that the developer is interested in. It would be really awesome if I could visually browse my tables and stored procedures and see what is related to what by primary key, foreign key, and referenced in stored procedures. I realize that I'm talking about two entirely different technologies and it's not a perfect analogy, but is there some similar tool that would allow me to visualize tables in my SQL database?

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• Encrypt/ Decrypt text file in Delphi?

  - by Hemant Kothiyal

  Hi i would like to know best encryption technique for text file encryption and ecryption. My Scenario: I have software having two type of users Administartor and Operators. Our requirement is to encrypt text file when Administrator enter data using GUI and save it. That encrypted file would be input for Operator and they just need to select it and use that file. Here file should be automatically decrypt data for further calculation when Operator select those files. Please help me which encryption/ decryption technique should i use?

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• Why does F10 (step over) in Visual Studio 2010 not work?

  - by maycil

  I also tried 2 solution. But It doesn't worked. Go to Tools Options menu in Visual Studio. Go to Debugging General menu item in left pane. In right view you will see and option Step over properties and operators (Managed only). Uncheck this option and then you are all set. and Go to Tools Options menu in Visual Studio. Go to Debugging General menu item in left pane. In right view you will see and option Enable Just My Code (Managed only). Uncheck this option and then you are all set.

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• can we write this in C++ switch ?

  - by jellly

  #include <iostream> using namespace std; int main(){ char i; cin >>i; switch (i){ case ('e'||'i'||'o'||'u'||'a'): cout<<"Vowel"; break; case ('+'||'-'||'/'||'*'||'%'): cout<<"Op"; break; } return 0; } if not than how can we use comparison or logical operators in switch ? & why cant we declare and initialize variable in single case without using scope ?

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• Javascript === vs == : Does it matter which "equal" operator I use?

  - by bcasp

  I'm using JSLint to go through some horrific JavaScript at work and it's returning a huge number of suggestions to replace == with === when doing things like comparing 'idSele_UNVEHtype.value.length == 0' inside of an if statement. I'm basically wondering if there is a performance benefit to replacing == with ===. Any performance improvement would probably be welcomed as there are hundreds (if not thousands) of these comparison operators being used throughout the file. I tried searching for relevant information to this question, but trying to search for something like '=== vs ==' doesn't seem to work so well with search engines...

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• Using ANTLR with Left-Recursive Rules

  - by CNevin561

  Basically Ive written a Parse for a language with just basic arithmetic operators ( +, -, * / ) etc, but for the minus and plus cases, the Abstract Syntax Tree which is generated has parsed them as right associative when they need to be left associative. Having a googled for a solution, i found a tutorial that suggests rewriting the rule from: Expression ::= Expression <operator> Term | Term as Expression ::= Term <operator> Expression*. However in my head this seems to generate the tree the wrong way round. Any pointers on a way to resolve this issue?

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• Is tertiary operator possible here?

  - by silow

  I'm trying to set $value1, $value2, $value3 entirely using tertiary operators. This is what it looks like without tertiary if ($chk1 == 20) { $value1 = true; if ($chk2 == 40) { $value2 = 100 ; $value3 = 300; } else { $value2 = 200 ; $value3 = 400; } } else { $value1 = false; } I can set $value2 and $value3, but not sure how to set $value1. Can it be done? if ($chk1 == 20) { $value1 = true; $value2 = ($chk2 == 40) ? 100 : 200; $value3 = ($chk2 == 40) ? 300 : 400; } else { $value1 = false; }

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• FastObjects.NET(is an OODB from Versant) performence in Real Scenerios?

  - by Lalit

  FastObjects.NET Saves the whole class object(if marked with attribute Persistent) at once in file system(using serilization or similar technology). They are promissing that it is even faster then normal SQL DB approach. My team also thought it is better and faster to save the whole object once instead of each field one by one. Defination of their website: FastObjects .NET 10.0 fully conforms to the Microsoft.NET 2.0 framework. Tightly integrated with Visual Studio 2005, it offers a developer-friendly, object-oriented alternative to a relational database for .NET persistence. I want to have your experiences of using FastObjects in production scenerio? They are promising for Indexing/Transaction/clustoring/replication.

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• Fractional Calculator in Java

  - by user2888881

  I am trying to create a fractional calculator in Java with inputs of mixed fractions, proper fractions, improper fractions or integers. It should include the four basic operators as well. The program should be set up as a loop where it is continuous until the user types "quit". I have coded the beginning loop but have no idea where to go from there. Please help, I am a beginner and would really appreciate it. Thank you again. This is what I have so far: import java.util.*; public class FractionCalculator { private static Scanner input; public static void main(String[] args) { input = new Scanner(System.in); String x = "quit"; System.out.println("Enter a fraction"); while (true) { String y = input.next(); if (y.equals(x)) { break; } } } }

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• Integrate existing Spring based web application with a CMS

  - by anne_developer

  We have stable spring based (spring 2.x) web application. We have a new requirement which is our data entry operators should be able to login to some kind of an admin module and simply change the text in the web pages, change the color etc. I have seen PHP based CMS’s that allows authorized user to change the content in WYSIWYG manner. If anyone of you knows such open source Java CMS or third party application, which can facilitate such thing, please let me know. Please note: we cannot write our application from scratch. We are looking for pluggable component.

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• EF Linq Product Sum when no records returned

  - by user1622713

  I’ve seen variations of this question all over the place but none of the answers work for me. Most of them are just trying to sum a single column too – nothing more complex such as the sum of a product as below: public double Total { get { return _Context.Sales.Where(t => t.Quantity > 0) .DefaultIfEmpty() .Sum(t => t.Quantity * t.Price); } } If no rows are returned I want to return zero. However if no rows are returned the .Sum() fails. There are various options of trying to insert Convert.ToDouble and using null coalesce operators, but they all still gave me errors. I’m sure I am missing a simple way to do this – any help greatly appreciated after too long banging head against google brick wall!

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• Why the streams in C++?

  - by oh boy

  As you all know there are libraries using streams such as iostream and fstream. My question is: Why streams? Why didn't they stick with functions similar to print, fgets and so on (for example)? They require their own operators << and >> but all they do could be implemented in simple functions like above, also the function printf("Hello World!"); is a lot more readable and logical to me than cout << "Hello World"; I also think that all of those string abstractions in C++ all compile down to (less efficient) standard function calls in binary.

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• Subtracting months/years from boost::posix_time::ptime

  - by Zack

  I have a boost::posix_time::ptime that points to March 31st 2010 like this: ptime p(date(2010, Mar, 31)); I would like to subtract a month (and possibly years) from this date. From the docs I see these two operators: ptime operator-(time_duration) and ptime operator-(days) but none of them can work with months/years. If I try and do: time_duration duration = hours(24 * 30); ptime pp = p - duration; I'm getting March 1st and if I'm trying: ptime pp = p - days(30); I'm still getting March 1st, while I'd like to get February 28th. How can I achieve my desired result? (I would like to get the desired result also when subtracting a month from March 28, 29, 30)

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