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• ASP.NET Thread Safety in aspx.cs code behind file

  - by Tim Michalski

  I am thinking of adding a DataContext as a member variable to my aspx.cs code-behind class for executing LinqToSql queries. Is this thread safe? I am not sure if a new instance of this code-behind class is created for each HTTP request, or if the instance is shared amongst all request threads? My fear is that I will get 10 simultaneous concurrent http requests that will be using the same database session. public partial class MyPage : System.Web.UI.Page { private DataContext myDB = new DataContext(); protected void MyAction_Click(object sender, EventArgs e) { myDB.DoWork(); } }

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• SQL to get range of results in alphabetical order

  - by Tom Gullen

  I have a table, tblTags which works in much the same way as StackOverflows tagging system. When I view a tags page, let's say the tag Tutorial I want to display the 10 tags before and after it in alphabetical order. So if we are given the tag Tutorial of ID 30 how can we return a record set in the order resembling: Tap Tart > Tutorial Umbrellas Unicorns Xylaphones I have thought of ways of doing this, badly, in my opinion as they involve retrieving ugly amounts of data. I'm not sure if it's possible to do something along the lines of (pseudo): SELECT RANGE(0 - 30) FROM tblTags ORDER BY Name ASC But how do you know the position of the tutorial tag in the list in an efficient manner without traversing the entire list until you find it? I'm using SQL Server 2008 R2 Express with LINQ if it makes any difference, SQL queries or LINQ would be great answers, thanks!

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• Aggregate functions in ANSI SQL

  - by morpheous

  I want to use multiple aggregate functions in a query. All the examples i have seem on aggregate functions however, are trivial. Typically, they are of the form: SELECT field1,agg_func1, agg_func2 GROUP BY SOME_COLUMNS HAVING agg_func1 OP SOME_SCALAR Where: OP: is a boolean operator (e.g. <, = etc) SOME_SCALAR: is a scalar (i.e. a constant number) What I want to know is if it is possible to write (IN ANSI SQL) queries like: SELECT field1,agg_func1, agg_func2, agg_func3 GROUP BY SOME_COLUMNS HAVING (agg_func1 OP1 agg_func2) OP2 (agg_func2 OP3 agg_func3) Where: OP[N] are boolean operators or ANSI SQL clause operators like 'BETWEEN', 'LIKE', 'IN' etc. Also, assuming this is possible (I have not seen any documentation saying otherwise) are there any efficiency/performance considerations (i.e. penalties) when the HAVING clause consists of a boolean expression combining the output of the aggregate functions - instead of the normal comparison of the output of the aggregate with a constant number (e.g. min('salary') 100 ) - which is often used in the most banal examples involving aggregate functions?

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• Parsing HTML with XPath and PHP

  - by Peter

  Is there a way (using XPath and PHP) to do the following (WITHOUT external XSLT files)? Remove all tables and their contents Remove everything after the first h1 tag Keep only paragraphs (INCLUDING their inner HTML (links, lists, etc)) I received an XSLT answer here, but I'm looking for XPATH queries that don't require external files. Currently, I've got the HTML in question loaded into a SimpleXmlElement via: $doc = @DOMDocument::loadHTML($xml); $data = simplexml_import_dom($doc); Now I need help with: $data = $data->xpath('??????'); Been working with this one for several days to no avail. I really appreciate the help. Edit: I don't particularly care what's inside the paragraphs, as I can use strip_tags to eliminate what I don't want. All I need to do is to isolate the paragraphs from the rest of the source. I suppose a more specific, accurate requirement would be this: Return only paragraphs (and their html contents) that aren't contained in tables, and only before the first h1 tag

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• Performance of Managed C++ Vs UnManaged/native C++

  - by bsobaid

  I am writing a very high performance application that handles and processes hundreds of events every millisecond. Is Unmanaged C++ faster than managed c++? and why? Managed C++ deals with CLR instead of OS and CLR takes care of memory management, which simplifies the code and is probably also more efficient than code written by "a programmer" in unmanaged C++? or there is some other reason? When using managed, how can one then avoid dynamic memory allocation, which causes a performance hit, if it is all transparent to the programmer and handled by CLR? So coming back to my question, Is managed C++ more efficient in terms of speed than unmanaged C++ and why?

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• ASP.NET Forms automation/serialization/binding

  - by creo

  I need to implement many forms in ASP.NET application (for IRS mostly). There are will be a lot of standard controls for each form (textboxes, dropdowns, checkboxes, radio). And business entity assigned to each. What's the best solution to automate this process? I need to: Have layout stored in DB (in XML). Layout must support several columns, tabbed interface Automatically bind business object values to the form Automatically read form values and write to business object Must support automatic validation Some basic workflows support would be good I used to work with TFS and saw how they implemented WorkItem templates (.wit files). In general this is all I need. But what framework did they build it on? How can I utilize this solution? I know about Dynamic Data only: http://www.asp.net/dynamicdata

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• Proper abstraction of the database tier in a 3 tier system?

  - by Earlz

  Hello, I am creating a 3 tier application. Basically it goes Client - (through optional server to be a thin-client) - Business Logic - Database Layer And basically making it so that there is never any skipping around. As such, I want for all of the SQL queries and such to be in the Database Layer. Well, now I'm a bit confused. I made a few static classes to start off the database tier but what should I do for the database connections? Should I just create a new database connection anytime I enter the Database Layer or would that be wasteful? Does Connection.Open() take time whenever you have a ConnectionPool? To me, it just feels wrong for the Business tier to have to pass in a IdbConnection object to the Database tier. It seems like the Database tier should handle all of that DB-specific code. What do you think? How can I do it the proper way while staying practical?

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• What Kind of Knowledge is Necessary For a Permon Who Does Not Have IT Background? [closed]

  - by skyflyer

  One of my colleagues joined our company, which by the way is a internet company, months ago as an on-line marketing specialist. He majored English in his college and has never deeply touched IT before. He says that to be a good on-line marketing specialist he needs to lean some basic IT skills in order to deliver superb work. According to him, things like Search Engine Optimization, monitoring competitors' web sites, design some functionality on web site and so on require IT entree-level knowledge. And he asks me what kind knowledge is helpful for him to do his job. I am stunted by his question. It is easy enough to answer, things like HTML, CSS, even Photo-shop are required in some job descriptions. Also, I believe some basic understanding of dynamic web site, static web site is helpful to him. On the other hand, as a techie I still feel my answer is awkward. What is your opinion on this? Always lot of thanks to you guys on SO.

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• Custom keys for Google App Engine models (Python)

  - by Cameron

  First off, I'm relatively new to Google App Engine, so I'm probably doing something silly. Say I've got a model Foo: class Foo(db.Model): name = db.StringProperty() I want to use name as a unique key for every Foo object. How is this done? When I want to get a specific Foo object, I currently query the datastore for all Foo objects with the target unique name, but queries are slow (plus it's a pain to ensure that name is unique when each new Foo is created). There's got to be a better way to do this! Thanks.

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• Using Rails and Rspec, how do you test that the database is not touched by a method

  - by Will Tomlins

  So I'm writing a test for a method which for performance reasons should achieve what it needs to achieve without using SQL queries. I'm thinking all I need to know is what to stub: describe SomeModel do describe 'a_getter_method' do it 'should not touch the database' do thing = SomeModel.create something_inside_rails.should_not_receive(:a_method_querying_the_database) thing.a_getter_method end end end EDIT: to provide a more specific example: class Publication << ActiveRecord::Base end class Book << Publication end class Magazine << Publication end class Student << ActiveRecord::Base has_many :publications def publications_of_type(type) #this is the method I am trying to test. #The test should show that when I do the following, the database is queried. self.publications.find_all_by_type(type) end end describe Student do describe "publications_of_type" do it 'should not touch the database' do Student.create() student = Student.first(:include => :publications) #the publications relationship is already loaded, so no need to touch the DB lambda { student.publications_of_type(:magazine) }.should_not touch_the_database end end end So the test should fail in this example, because the rails 'find_all_by' method relies on SQL.

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• How to estimate memory need by XPathDocument for a specific xml file

  - by bill seacham

  Is there any way to estimate the memory requirement for creating an XpathDocument instance based on the file size of the xml? XpathDocument xdoc = new XpathDocument(xmlfile); Is there any way to programmatically stop the process of creating the XpathDocument if memory drops to a very low level? Since it loads the entire xml into memory, it would be nice to know ahead of time if the xml is too big. What I have found is that when I create a new XpathDocument with a big xml file, an outofmemory exception is never fired, but that the process slows to a crawl, only 5 Mb of memory remains a available and the Task Manager reports it is not responding. This happened with a 266 Mb xml file when there was 584 Mb of ram. I was able to load a 150 Mb file with no problems in 18. After loading the xml, I want to do xpath queries using an XpathNavigator and an XpathNodeIterator. I am using .net 2.0, xp sp3.

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• HTML: How to get a child element to show behind (lower z-index) than its parent

  - by dclowd9901

  I need for a certain dynamic element to always appear on top of another element, no matter what order in the DOM tree they are. Is this possible? I've tried z-index (with position: relative), and it doesn't seem to work. I hate to be vague, but this is the simplest way I can think of asking this question without explaining its purpose ad nauseum. So, to recap, I need <div class="a"> <div class="b"></div> </div> <div class="b"> <div class="a"></div> </div> To display exactly the same when rendered. And for flexibility purposes (I'm planning on distributing a plugin that needs this functionality), I'd really like to not have to resort to absolute or fixed positioning.

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• Under what circumstances does Groovy use AbstractConcurrentMap?

  - by Electrons_Ahoy

  (Specifically, org.codehaus.groovy.util.AbstractConcurrentMap) While doing some profiling of our application thats mixed Java/Groovy, I'm seeing a lot of references to the AbstractConcurrentMap class, none of which are explicit in the code base. Does groovy use this class when maps are instantiated in the groovy dynamic def myMap = [:] style? Are there rules somewhere about when groovy chooses to use this as opposed to, say, java.util.HashMap? And does anyone have any performance information comparing the two? My rough "eyeball check" says that AbstractConcurrentMap seems to be much slower - anyone know if I'm right?

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• HQL multiple updates. Is there a better way?

  - by folone

  I have a Map, that I want to persist. The domain object is something like this: public class Settings { private String key; private String value; public String getKey() { ... } public String getValue() { ... } public void setKey() { ... } public void setValue() { ... } } The standard approach is to generate a Setting for each pair, and saveOrUpdate() it. But it generates way too much queries, because I need to save lots of settings at a time, and it really affects perfomance. Is there a way to do this using one update query?

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• Core Data and BOOL setup

  - by John Valen

  I am working on an app that uses Core Data as its backend for managing SQLite records. I have everything working with strings and numbers, but have just tried adding BOOL fields and can't seem to get things to work. In the .xcdatamodel, I have added a field to my object called isCurrentlyForSale which is not Optional, not Transient, and not Indexed. The attribute's type is set to Boolean with default value NO. When I created the class files from the data model, the boilerplate code added for this property in the .h header was: @property (nonatomic, retain) NSNumber * isCurrentlyForSale; along with the @dynamic isCurrentlyForSale; in the .m implementation file. I've always worked with booleans as simple BOOLs. I've read that I could use NSNumber's numberWithBool and boolValue methods, but this seems like an aweful lot of extra code for something so simple. Can the @property in the header be changed to a simple BOOL? If so is there anything to watch out for? Thanks -John

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• how do I send stuff to method using the JQuery Ajax method

  - by nisardotnet

  $.ajax({ type: "POST", url: "WebService.asmx/AddVisitor", data: "{'fname':'dave', 'lname':'ward'}", contentType: "application/json; charset=utf-8", dataType: "json" }); I have an Asp.Net WebMethod that takes a firstName, lastName.....as a parameter, how do I send that stuff to that method using the JQuery Ajax method. if i hardcode the above it works without any problem but if i pass dynamic it fails var firstName = $("[id$='txtFirstName']"); var lastName = $("[id$='txtLastName']"); //data: "{'firstName':'Chris','lastName':'Brandsma'}"<br> data: "{'firstname':'" + escape(firstName.val()) + "','lastName':'" + escape(lastName.val()) + "'}", my WebMethod looks like this [WebMethod] public bool AddVisitor(string firstName, string lastName) { return true; } what wrong here? i have tried with eval and escape none of that works. Thanks for any help.

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• Nginx logic (if cookie set, redirect here...) Is it possible?

  - by Matthew Steiner

  So, I have a pretty basic need, but I can't figure out if it's even possible, much less how to do it. I have a main page that anyone can see. Most of the rest of the application can be seen only if logged in (hence, a "set cookie"). So I was thinking, as long as they don't have a cookie set, they can just see a cached version of nginx. I can get it caching with this: proxy_cache STATIC; proxy_cache_valid 200 1d; proxy_cache_use_stale error timeout invalid_header updating http_500 http_502 http_503 http_504; And it helps a ton. (instead of 15 requests per second it gets over 1000). Now I just need some sort of "server logic" to say only serve the cached page if they have no cookie, otherwise, load the dynamic page (which will automatically redirect them into the app). Any ideas?

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• Interesting AS3 hash situation. Is it really using strict equality as the documentation says?

  - by Triynko

  AS3 Code: import flash.utils.Dictionary; var num1:Number = Number.NaN; var num2:Number = Math.sqrt(-1); var dic:Dictionary = new Dictionary( true ); trace(num1); //NaN trace(num2); //NaN dic[num1] = "A"; trace( num1 == num2 ); //false trace( num1 === num2 ); //false trace( dic[num1] ); //A trace( dic[num2] ); //A Concerning the key comparison method... "The Dictionary class lets you create a dynamic collection of properties, which uses strict equality (===) for key comparison. When an object is used as a key, the object's identity is used to look up the object, and not the value returned from calling toString() on it." If Dictionary uses strict equality, as the documentation states, then how is it that num1 === num2 is false, and yet dic[num1] resolves to the same hash slot as dic[num2]?

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• which is better, creating a materialized view or a new table?

  - by Carson

  I have some demanding mysql queries that are needed to grap same up-to-date datasets from 5-7 mysql tables. I am thinking of creating a table or materialized view to gather all demanding columns from other tables, so as to increase performance. If I create that table, I may need to do extra insert / update / delete operation each time other tables updated. if I create materialized view, I am worrying if the performance can be greatly improved. Because data from other tables are changing very frequently. Most likely, the view may need to be created first everytime before selecting it. Any ideas? e.g. how to cache? other extra measures I can do?

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• Best data store for billions of rows

  - by Jody Powlette

  I need to be able to store small bits of data (approximately 50-75 bytes) for billions of records (~3 billion/month for a year). The only requirement is fast inserts and fast lookups for all records with the same GUID and the ability to access the data store from .net. I'm a SQL server guy and I think SQL Server can do this, but with all the talk about BigTable, CouchDB, and other nosql solutions, it's sounding more and more like an alternative to a traditional RDBS may be best due to optimizations for distributed queries and scaling. I tried cassandra and the .net libraries don't currently compile or are all subject to change (along with cassandra itself). I've looked into many nosql data stores available, but can't find one that meets my needs as a robust production-ready platform. If you had to store 36 billion small, flat records so that they're accessible from .net, what would choose and why?

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• Help System.Web.Compilation.BuildManager find a type in a non-referenced assembly

  - by asbjornu

  I'm trying to write a plug-in system where assemblies can be dropped in a folder that ASP.NET has no knowledge about. This plug-in system works fine for ASP.NET MVC based assemblies, but for old-school WebForm assemblies (where the .aspx files Inherits the System.Web.UI.Page derived classes) System.Web.Compilation.BuildManager is responsible for compiling the .aspx file into a dynamic assembly. My problem is that the BuildManager knows nothing about the assemblies within my plug-in folder and it seems to be absolutely nothing I can do to help it. If I do: BuildManager.GetType("Type.Defined.In.Plugin.Assembly", true, true) it throws. If I first get a reference to the Type and then try: var instance = BuildManager.CreateInstanceFromVirtualPath(path, type); it still throws, even though I've now passed in the specific type it needs to compile the .aspx file. Is there anything I can do to help BuildManager find the types it needs to compile the .aspx file?

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• xcode - warning there's no getter/setter for property not even mentioned in the code!!

  - by alexeyndru

  I got the warning : property 'textField' requires method '-textField' to be defined - use @synthesize, @dynamic or provide a method implementation. Now, there is no such property defined in my project! More bizarre, if I just click save in Interface builder and build again, the build is successful - though, right on the line with '@end' the warning appears. Also weird: if I begin to write some code ..and then delete it just the way it was before writing it (maybe not code..anything) and then build&go the warning with the textField appears again. Could be a bug of sdk? What could be happening?

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• Update options to jQuery slider via form

  - by Coughlin

  I have a jQuery Slider, and I am trying to make it more dynamic by adding three input fields: min max step I want to take those fields and then onblur update my slider options. I read that you can set options like this: $('.selector').slider('option', 'max', 7); And do the same for min,step, etc along with the other options. I tried playing with it yesterday, but I'm not sure how to get it to update. I am using a form with no submit button, so just change on blur. I know I would get the .val() of the input and set it to a variable then would it be: $('.selector').slider('option', 'max', var_here); Any thoughts?

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• INET_ATON() and INET_NTOA() in PHP?

  - by blerh

  I want to store IP addresses in my database, but I also need to use them throughout my application. I read about using INET_ATON() and INET_NTOA() in my MySQL queries to get a 32-bit unsigned integer out of an IP address, which is exactly what I want as it will make searching through the database faster than using char(15). The thing is, I can't find a function that does the same sort of thing in PHP. The only thing I came across is: http://php.net/manual/en/function.ip2long.php So I tested it: $ip = $_SERVER['REMOTE_ADDR']; echo ip2long($ip); And it outputs nothing. In the example they gave it seems to work, but then again I'm not exactly sure if ip2long() does the same thing as INET_ATON(). Does someone know a PHP function that will do this? Or even a completely new solution to storing an IP address in a database? Thanks.

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• File listing application on Windows : what language ?

  - by Studer

  I need to create a simple application/script able to list the hierarchy of a folder containing subfolders and files (mostly PDF), so that a user can browse easily these files and maybe have a quick preview of them. The files are all on an internal file server, so the dynamic aspects should all be client-sided. My goal (and what my boss want) is to provide some sort of an HTML page listing, to have something like this. The only problem I have now is that I cannot install anything on computers, so I cannot use PHP, Python, ... This application will only runs on Windows in Internet Explorer. What are the different possibilities I have ? I don't know if I can do this but I was thinking of using HTML + Flex. Thanks for helping.

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