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  • Why use hashing to create pathnames for large collections of files?

    - by Stephen
    Hi, I noticed a number of cases where an application or database stored collections of files/blobs using a has to determine the path and filename. I believe the intended outcome is a situation where the path never gets too deep, or the folders ever get too full - too many files (or folders) in a folder making for slower access. EDIT: Examples are often Digital libraries or repositories, though the simplest example I can think of (that can be installed in about 30s) is the Zotero document/citation database. Why do this? EDIT: thanks Mat for the answer - does this technique of using a hash to create a file path have a name? Is it a pattern? I'd like to read more, but have failed to find anything in the ACM Digital Library

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  • Silverlight 4 ComboBox - Binding to Nullable data (tried TargetNullValue but not working as expected)

    - by Laurence
    (Please note - I am a Silverlight beginner and am looking for the simplest solution here, e.g. that doesn't involve writing/installing a replacement for the ComboBox control!) This is an issue with a Silverlight 4 application that uses the View Model (MVVM) approach. I have a simple form for editing a "Product" object. Product has a CategoryID property which is nullable (int?). A ComboBox is used to view and set the CategoryID - this is bound to an ObservableCollection of Categories. Product also has number of non-nullable properties bound to TextBoxes. I want the user to see "N/A" in the ComboBox for a product with no category, and to be use this "N/A" option to set CategoryID to null. So, I manually added a Category object with CategoryID=0 and CategoryName="N/A" to the collection; then I set TargetNullValue=0 in the SelectedValue Binding of the ComboBox. My thinking was - when the ComboBox SelectedValue was bound to a null CategoryID it would substitute zero, and therefore select the "N/A" option. When editing a Product with a non-null CategoryID, everything works. However when a null CategoryID is found, two problems occur: No option is selected in the ComboBox (its blank) The ComboBox binding seems broken from this point onwards - any Product I subsequently edit (incl. ones with a non-null CategoryID) have nothing selected in the ComboBox (its still populated with all categories - just no selected item). I've seen reports of problem #2 (here, here) but I was under the impression that #1 should have worked. What am I missing to get the "N/A" option to be selected? XAML for ComboBox: <ComboBox x:Name="cboCategory" ItemsSource="{Binding colCategories, Mode=OneWay}" SelectedValuePath="CategoryID" DisplayMemberPath="CategoryName" SelectedValue="{Binding CurrentProduct.CategoryID, Mode=TwoWay, TargetNullValue=0}" Height="24" Width="344"></ComboBox>

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  • Why Could Linq to Sql Submit Changes Fail for Updates Despite Data in Change Set

    - by KevDog
    I'm updating a set of objects, but the update fails on a SqlException that says "Incorrect Syntax near 'Where'". So I crack open SqlProfiler, and here is the generated SQL: exec sp_executesql N'UPDATE [dbo].[Addresses] SET WHERE ([AddressID] = @p0) AND ([StreetAddress] = @p1) AND ([StreetAddress2] = @p2) AND ([City] = @p3) AND ([State] = @p4) AND ([ZipCode] = @p5) AND ([CoordinateID] = @p6) AND ([CoordinateSourceID] IS NULL) AND ([CreatedDate] = @p7) AND ([Country] = @p8) AND (NOT ([IsDeleted] = 1)) AND (NOT ([IsNonSACOGZip] = 1))',N'@p0 uniqueidentifier,@p1 varchar(15),@p2 varchar(8000),@p3 varchar(10),@p4 varchar(2),@p5 varchar(5),@p6 uniqueidentifier,@p7 datetime,@p8 varchar(2)',@p0='92550F32-D921-4B71-9622-6F1EC6123FB1',@p1='125 Main Street',@p2='',@p3='Sacramento',@p4='CA',@p5='95864',@p6='725E7939-AEE3-4EF9-A033-7507579B69DF',@p7='2010-06-15 14:07:51.0100000',@p8='US' Sure enough, no set statement. I also called context.GetChangeSet() and the proper values are in the updates section. Also, I checked the .dbml file and all of the properties Update Check values are 'Always'. I am completely baffled on this one, any help out there?

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  • WPF ComboBox drop-down (data bound) values not changing

    - by Jefim
    I bind the ItemsSource of a ComboBox to an ObservableCollection<MyClass>. In code I change the collection (e.g. edit the MyClass.Name property). The problem: the change is not reflected in the dropdown box if the ComboBox, yet when I seled the item from the dropdown it is displayed correctly in the selected item box of the ComboBox. What's going on? :) PS MyClass has INotifyPropertyChanged implemented

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  • amount of data returned by wcf 3.0 service contract method causes error

    - by ferrell carr
    CommuncationException was unhandled The maximum message size quota for incoming messages (65536) has been exceeded. To increase the quota, use the MaxReceivedMessageSize property on the appropriate binding element. here is my svc.map file <?xml version="1.0" encoding="utf-8"?> <ServiceReference> <ProxyGenerationParameters ServiceReferenceUri="http://d3w9501/SimpleWCF/SimpleWCF.svc" Name="svc" NotifyPropertyChange="False" UseObservableCollection="False"> </ProxyGenerationParameters> <EndPoints> <EndPoint Address="http://d3w9501.americas.hpqcorp.net/SimpleWCF/SimpleWCF.svc" BindingConfiguration="BasicHttpBinding_ISimpleWCF" Contract="TestSimpleWCF.svc.ISimpleWCF" > </EndPoint> <bindings> <basicHttpBinding> <binding name="BasicHttpBinding_ISimpleWCF" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" > <security mode="None" /> </binding> </basicHttpBinding> </bindings> </EndPoints> </ServiceReference>

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  • WinForms / .Net interactive world map - how?

    - by FerretallicA
    In a CD collection program, I have each artist's country of origin stored in the main database and want to display a map of the world which: Colour-codes each country depending on the number of CDs by artists in that country Allows clicking on each country to filter a list of CDs to only ones by artists in that country This is a heavily simplified version of what I'm trying to do, but if I can at least get this far the rest should be easy enough to figure out. So far the closest thing I've found to what I'm trying to do is here: http://www.synergetechsolutions.com/blog/analytics-world-map-control Ideally I don't want to be embedding Flash in my program though, and the only other solutions I've found all involve SVG which I haven't managed to get working in practice outside of a web browser control (and I DEFINITELY don't want to be embedding a browser in the forms). Something in pure managed code and either GDI+ or WPF would be preferable. Are there any existing components that would get me started, or can anyone suggest how to approach it from scratch?

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  • Rails ActiveRecord- has_many through and belongs_to a related model

    - by Nick
    I have 3 models sites, user_favorites and users. Relevant relationships: class Site < ActiveRecord::Base has_many :users, :through => :user_favorites class UserFavorite < ActiveRecord::Base belongs_to :user, :counter_cache => true belongs_to :site end class User < ActiveRecord:Base has_many :user_favorites has_many :sites, :through => :user_favorites All of that works just fine. I'd like to add a new attribute to the Site model to indicate which user created it. I don't believe this constitutes a has_and_belongs_to_many scenario. A site has many users through user_favorites but I want it to belong to a single user reflecting the owner/creator. I'm wondering what the ORM best practice is for this. SQL wise I'd just use different joins depending on what I was trying to query with a created_by FK in Site. Sorry if I'm missing something basic here. Thanks

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  • Unable to get data from a WCF client

    - by Scott
    I am developing a DLL that will provide sychronized time stamps to multiple applications running on the same machine. The timestamps are altered in a thread that uses a high performance timer and a scalar to provide the appearance of moving faster than real-time. For obvious reasons I want only 1 instance of this time library, and I thought I could use WCF for the other processes to connect to this and poll for timestamps whenever they want. When I connect however I never get a valid time stamp, just an empty DateTime. I should point out that the library does work. The original implementation was a single DLL that each application incorporated and each one was synced using windows messages. I'm fairly sure it has something to do with how I'm setting up the WCF stuff, to which I am still pretty new. Here are the contract definitions: public interface ITimerCallbacks { [OperationContract(IsOneWay = true)] void TimerElapsed(String id); } [ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(ITimerCallbacks))] public interface ISimTime { [OperationContract] DateTime GetTime(); } Here is my class definition: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)] public class SimTimeServer: ISimTime The host setup: // set up WCF interprocess comms host = new ServiceHost(typeof(SimTimeServer), new Uri[] { new Uri("net.pipe://localhost") }); host.AddServiceEndpoint(typeof(ISimTime), new NetNamedPipeBinding(), "SimTime"); host.Open(); and the implementation of the interface function server-side: public DateTime GetTime() { if (ThreadMutex.WaitOne(20)) { RetTime = CurrentTime; ThreadMutex.ReleaseMutex(); } return RetTime; } Lastly the client-side implementation: Callbacks myCallbacks = new Callbacks(); DuplexChannelFactory pipeFactory = new DuplexChannelFactory(myCallbacks, new NetNamedPipeBinding(), new EndpointAddress("net.pipe://localhost/SimTime")); ISimTime pipeProxy = pipeFactory.CreateChannel(); while (true) { string str = Console.ReadLine(); if (str.ToLower().Contains("get")) Console.WriteLine(pipeProxy.GetTime().ToString()); else if (str.ToLower().Contains("exit")) break; }

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  • Retrieving & Displaying data from csv files using AJAX

    - by JJ
    I need to provide a feature such that the user is able to upload a csv file.Once the uploading is done I need to retrieve each value and show it on a grid which is implemented using far point(http://www.fpoint.com/products/spread/spread.aspx).But all this has to be done without the page being refreshed.I use asp.net 2.0 & Ajax Pro.Remember I cannot use the inbuilt AJAX feature provided by microsoft .To be precise I need something similar to the lines of attaching a file using gmail. Thanks & Regards Bikram

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  • NSFetchedResultsController deallocated instance

    - by Jesse Armand
    Anyone ever encountered this ? -[NSFetchedResultsController _restoreCachedSectionInfo]: message sent to deallocated instance While performing fetch with performFetch: using NSFetchedResultsController instance. I'm sure the NSFetchedResultsController is retained before performing the fetch.

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  • sending data packet just before closing socket

    - by xopht
    Before disconnect the client, the server wants to send some info to the client - why do I(server) disconnect you(client). If I send packet to the info and close the client socket immediately, closesocket() returns -1 and if I use linger option to work closesocket() successfully, the info cannot be sent completely. How can I complete this and is it possible to know socket buffer is empty(means my packet sent all)? thx.

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  • ASP.NET data bind two-way, bi-directional from code behind

    - by Konrad
    Hello, so for two-way (bi-directional) databinding in ASP, we do this... <asp:textbox id="txtField" runat="server" text='<%# Bind("SomeField") %>'> </asp:textbox> SomeField is located on the DataSource of the DetailsView that serves as the container for the textbox. Alternatively I could do this from code-behind (using the textbox's OnDataBinding event): protected void SomeField_OnDataBinding(object sender, EventArgs e) { ((TextBox)sender).Text = Eval("SomeField").ToString(); } However, EVAL is read-only...how can I specify Bind (two-way) from code-behind?

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  • Turning A Stacked List into workable data

    - by BoSox
    In Excel I have a list of names that in the cell appear stacked, and I want each name in its own column. I was thinking Python may be a good way to do this? Example: Joe Smith John Hawk Mike Green Lauren Smith One cell will look exactly like that, with each name on its line within the cell but all of the names contained in the cell. I have 50 cells each with 1-20 stacked names and I want to put each name in its own cell on a given row. So, in my example all of those names would occupy the same row but each would have their own column. Any ideas?

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  • Is it possible to add IPTC data to a JPG using python when no such data already exists?

    - by ventolin
    With the IPTCInfo module under Python (http://snippets.dzone.com/posts/show/768 for more info) it's possible to read, modify and write IPTC info to pictures. However, if a JPG doesn't already have IPTC information, the module simply raises an exception. It doesn't seem to be able to create and add this metadata information itself. What alternatives are there? I've googled for the past hour but to no avail whatsoever.

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  • creative way for implementing Data object with its corresponding business logic class in java

    - by ekeren
    I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity's sake let's call the classes Business a BusinessData and I prefix for their Interfaces. All the getter and setter are delegated from Business class to BusinessData class. I thought about implementing IBusinessData interface that will contain all the getter and setters and IBusiness interface that will extend it. I can either make Business extend BuisnessData so I will not need to implement all getter and setter delegates, or make some abstract class ForwardingBusinessData that will only delegate getter and setters. Any of the above option I lose my hierarchy freedom, do any of you have any creative solutions for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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  • How to convert an application to be a database independent app ?

    - by Eslam
    I have a java web application that has informix DB as it's back end database , now i take a decision to make my app work with SqlServer so i changed all the informix related syntax into SqlServer, and i may take a decision in the future to switch into oracle so the pain will be repeated again and again, as a result i decided to make my application a DataBase independent one that's able to work with any DB vendor smoothly, but i have no idea till now about how to do that, so your ideas is welcomed.

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  • Cleansing string / input in Coldfusion 9

    - by Jakub
    I have been working with Coldfusion 9 lately (background in PHP primarily) and I am scratching my head trying to figure out how to 'clean/sanitize' input / string that is user submitted. I want to make it HTMLSAFE, eliminate any javascript, or SQL query injection, the usual. I am hoping I've overlooked some kind of function that already comes with CF9. Can someone point me in the proper direction?

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  • Question on Binary Search Trees.

    - by AGeek
    Hi, I was thinking of implementing a binary search trees. I have implemented some very basic operations such as search, insert, delete. Please share your experiences as to what all other operations i could perform on binary search trees, and some real time operations(basic) that is needed every time for any given situation.. I hope my question was clear.. Thanks.

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  • Ember nested route. Load more models

    - by user3568719
    JsBin http://jsbin.com/EveQOke/153/ I know how to load more then one model to a route, using Ember.RSVP.hash. (see Jsbin Children menu). I use dynamic part to access one elem from a collection children/1. But i cant load more models to a nested resource. In my example i want to populate all the toys for a select, not just list the toys of the child. I have tried to access the model of the route children App.ChildRoute = Ember.Route.extend({ model: function(param){ return Ember.RSVP.hash({ allToys: this.modelFor("children"), child:this.store.find('child', param.child_id) }); } }); and use its model's toy property (since there have already loaded all of the toys) child.hbs <h4>All avaiable toys</h4> <table> {{#each toy in model.allToys.toys}} <tr> <td>{{toy.name}}</td> </tr> {{/each}} </table>

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  • Need sorted dictionary designed to find values with keys less or greater than search value

    - by Captain Comic
    Hi I need to have objects sorted by price (decimal) value for fast access. I need to be able to find all objects with price more then A or less than B. I was thinkg about SortedList, but it does not provide a way to find ascending or descending enumerator starting from given key value (say give me all objects with price less than $120). Think of a system that accepts items for sell from users and stores them into that collection. Another users want to find items cheaper than $120. Basically what i need is tree-based collection and functionality to find node that is smaller\greater\equal to provided key. Please advice.

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  • SQL Server 2005-data count

    - by megala
    hi i created project using asp.net and sql server 2005.I created table and inserted datainto sqlserver 2005. but i dont how to find the(count) number of records stored in the table.how to find this?

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  • Decode base64 data as array in Python

    - by skerit
    I'm using this handy Javascript function to decode a base64 string and get an array in return. This is the string: base64_decode_array('6gAAAOsAAADsAAAACAEAAAkBAAAKAQAAJgEAACcBAAAoAQAA') This is what's returned: 234,0,0,0,235,0,0,0,236,0,0,0,8,1,0,0,9,1,0,0,10,1,0,0,38,1,0,0,39,1,0,0,40,1,0,0 The problem is I don't really understand the javascript function: var base64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.split(""); var base64inv = {}; for (var i = 0; i < base64chars.length; i++) { base64inv[base64chars[i]] = i; } function base64_decode_array (s) { // remove/ignore any characters not in the base64 characters list // or the pad character -- particularly newlines s = s.replace(new RegExp('[^'+base64chars.join("")+'=]', 'g'), ""); // replace any incoming padding with a zero pad (the 'A' character is zero) var p = (s.charAt(s.length-1) == '=' ? (s.charAt(s.length-2) == '=' ? 'AA' : 'A') : ""); var r = []; s = s.substr(0, s.length - p.length) + p; // increment over the length of this encrypted string, four characters at a time for (var c = 0; c < s.length; c += 4) { // each of these four characters represents a 6-bit index in the base64 characters list // which, when concatenated, will give the 24-bit number for the original 3 characters var n = (base64inv[s.charAt(c)] << 18) + (base64inv[s.charAt(c+1)] << 12) + (base64inv[s.charAt(c+2)] << 6) + base64inv[s.charAt(c+3)]; // split the 24-bit number into the original three 8-bit (ASCII) characters r.push((n >>> 16) & 255); r.push((n >>> 8) & 255); r.push(n & 255); } // remove any zero pad that was added to make this a multiple of 24 bits return r; } What's the function of those "<<<" and "" characters. Or is there a function like this for Python?

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  • SQl Server - Hierarchical Data

    - by JMSA
    I use SQL Server 2000. Suppose I have two tables like the following: Area ---------------------------------- ID| Name | HierarchyLevel ---------------------------------- 1 | World | 1 2 | America| 2 3 | Europe | 2 4 | Africa | 2 5 | USA | 3 and AreaHierarchy ------------------------ ID | ParentID | ChildID ------------------------ 1 | 1 | 2 2 | 1 | 3 3 | 1 | 4 4 | 2 | 5 where AreaHierarchy.ParentID and AreaHierarchy.ChildID are FKs of Area.ID How can I find the nth parent of USA? Is it possible without looping? Probably not.

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  • Getting RAW Soap Data from a Web Reference Client running in ASP.net

    - by Harry
    I'm trying to trouble shoot a web service client in my current project. I'm not sure of the platform of the Service Server (Most likely LAMP). I believe there is a fault on their side of the fence as i have eliminated the potential issues with my client. The client is a standard ASMX type web reference proxy auto generated from the service WSDL. What I need to get to is the RAW SOAP Messages (Request and Responses) What is the best way to go about this?

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