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  • I need help with a SQL query. Fetching an entry, it's most recent revision and it's fields.

    - by Tigger ate my dad
    Hi there, I'm building a CMS for my own needs, and finished planning my database layout. Basically I am abstracting all possible data-models into "sections" and all entries into one table. The final layout is as follows: Database diagram: I have yet to be allowed to post images, so here is a link to a diagram of my database. Entries (section_entries) are children of their section (sections). I save all edits to the entries in a new revision (section_entries_revisions), and also track revisions on the sections (section_revisions), in order to match the values of a revision, to the fields of the section that existed when the entry-revision was made. The section-revisions can have a number of fields (section_revision_fields) that define the attributes of entries in the section. There is a many-to-many relationship between the fields (section_revision_fields) and the entry-revisions (section_entry_revisions), that stores the values of the attributes defined by the section revision. Feel free to ask questions if the diagram is confusing. Now, this is the most complex SQL I've ever worked with, and the task of fetching my data is a little daunting. Basically what i want help with, is fetching an entry, when the only known variables are; section_id, section_entry_id. The query should fetch the most recent revision of that entry, and the section_revision model corresponding to section_revision_id in the section_entry_revisions table. It should also fetch the values of the fields in the section-revision. I was hoping for a query result, where there would be as many rows as fields in the section. Each row would contain the information of the entry and the section, and then information for one of the fields (e.g. each row corresponding to a field and it's value). I tried to explain the best I could. Again, feel free to ask questions if my description somehow lacking. I hope someone is up for the challenge. Best regards. :-)

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  • How do you force Outlook 2007 to re-index it's seach on Windows XP SP 3?

    - by Aaron K
    So I have a Windows XP SP 3 machine which is running Outlook 2007. When I search in Outlook for an email that exists using a basic keyword, like say "MySQL", I get no results. However, Outlook gives me the following message: Search results may be incomplete because items are still being indexed. Click here for more details. When I click, I get the following: Outlook is currently indexing your items. Search results may be incomplete because items are still being indexed. 8783 items remaining in "Mailbox - USER" 8812 items remaining across all open mailboxes. The thing is, these are the numbers it has been reporting for several days, and Outlook is open for 8 hours a day. It does not seem like the index is working. As best I can tell, the index seemed to stop about 3 weeks ago. How can I force Outlook 2007 to re-index everything and start working properly again?

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  • Joomla Sub-Menu Won't Expand

    - by Ben Gribaudo
    Hello, The popular items menu on www.nfpn.org (displayed in right side bar) has sub-menu items defined. When someone navigates to a top-level page that's represented in that menu, I'd like for the child items to be displayed. I've played with various mod_mainmenu settings for that menu (in the modules section) without success. How would I get the appropriate sub-menu to expand? I'm using Joomla 1.5.21. Thank you, Ben

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  • TFS API-Process Template currently applied to the Team Project

    - by Tarun Arora
    Download Demo Solution - here In this blog post I’ll show you how to use the TFS API to get the name of the Process Template that is currently applied to the Team Project. You can also download the demo solution attached, I’ve tested this solution against TFS 2010 and TFS 2011.    1. Connecting to TFS Programmatically I have a blog post that shows you from where to download the VS 2010 SP1 SDK and how to connect to TFS programmatically. private TfsTeamProjectCollection _tfs; private string _selectedTeamProject;   TeamProjectPicker tfsPP = new TeamProjectPicker(TeamProjectPickerMode.SingleProject, false); tfsPP.ShowDialog(); this._tfs = tfsPP.SelectedTeamProjectCollection; this._selectedTeamProject = tfsPP.SelectedProjects[0].Name; 2. Programmatically get the Process Template details of the selected Team Project I’ll be making use of the VersionControlServer service to get the Team Project details and the ICommonStructureService to get the Project Properties. private ProjectProperty[] GetProcessTemplateDetailsForTheSelectedProject() { var vcs = _tfs.GetService<VersionControlServer>(); var ics = _tfs.GetService<ICommonStructureService>(); ProjectProperty[] ProjectProperties = null; var p = vcs.GetTeamProject(_selectedTeamProject); string ProjectName = string.Empty; string ProjectState = String.Empty; int templateId = 0; ProjectProperties = null; ics.GetProjectProperties(p.ArtifactUri.AbsoluteUri, out ProjectName, out ProjectState, out templateId, out ProjectProperties); return ProjectProperties; } 3. What’s the catch? The ProjectProperties will contain a property “Process Template” which as a value has the name of the process template. So, you will be able to use the below line of code to get the name of the process template. var processTemplateName = processTemplateDetails.Where(pt => pt.Name == "Process Template").Select(pt => pt.Value).FirstOrDefault();   However, if the process template does not contain the property “Process Template” then you will need to add it. So, the question becomes how do i add the Name property to the Process Template. Download the Process Template from the Process Template Manager on your local        Once you have downloaded the Process Template to your local machine, navigate to the Classification folder with in the template       From the classification folder open Classification.xml        Add a new property <property name=”Process Template” value=”MSF for CMMI Process Improvement v5.0” />           4. Putting it all together… using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using Microsoft.TeamFoundation.Client; using Microsoft.TeamFoundation.VersionControl.Client; using Microsoft.TeamFoundation.Server; using System.Diagnostics; using Microsoft.TeamFoundation.WorkItemTracking.Client; namespace TfsAPIDemoProcessTemplate { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private TfsTeamProjectCollection _tfs; private string _selectedTeamProject; private void btnConnect_Click(object sender, EventArgs e) { TeamProjectPicker tfsPP = new TeamProjectPicker(TeamProjectPickerMode.SingleProject, false); tfsPP.ShowDialog(); this._tfs = tfsPP.SelectedTeamProjectCollection; this._selectedTeamProject = tfsPP.SelectedProjects[0].Name; var processTemplateDetails = GetProcessTemplateDetailsForTheSelectedProject(); listBox1.Items.Clear(); listBox1.Items.Add(String.Format("Team Project Selected => '{0}'", _selectedTeamProject)); listBox1.Items.Add(Environment.NewLine); var processTemplateName = processTemplateDetails.Where(pt => pt.Name == "Process Template") .Select(pt => pt.Value).FirstOrDefault(); if (!string.IsNullOrEmpty(processTemplateName)) { listBox1.Items.Add(Environment.NewLine); listBox1.Items.Add(String.Format("Process Template Name: {0}", processTemplateName)); } else { listBox1.Items.Add(String.Format("The Process Template does not have the 'Name' property set up")); listBox1.Items.Add(String.Format("***TIP: Download the Process Template and in Classification.xml add a new property Name, update the template then you will be able to see the Process Template Name***")); listBox1.Items.Add(String.Format(" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -")); } } private ProjectProperty[] GetProcessTemplateDetailsForTheSelectedProject() { var vcs = _tfs.GetService<VersionControlServer>(); var ics = _tfs.GetService<ICommonStructureService>(); ProjectProperty[] ProjectProperties = null; var p = vcs.GetTeamProject(_selectedTeamProject); string ProjectName = string.Empty; string ProjectState = String.Empty; int templateId = 0; ProjectProperties = null; ics.GetProjectProperties(p.ArtifactUri.AbsoluteUri, out ProjectName, out ProjectState, out templateId, out ProjectProperties); return ProjectProperties; } } } Thank you for taking the time out and reading this blog post. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Have you come across a better way of doing this, please share your experience here. Questions/Feedback/Suggestions, etc please leave a comment. Thank You! Share this post : CodeProject

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  • Using Umbraco&rsquo;s Dropdown Datatype

    - by MightyZot
    In Umbraco, you could consider document types like models and data types as property types for those modes. For example, you may create a document type called “Prices” to represent a page that displays a list of prices. And, then, you might create a document type called “Price Item” to represent the price list items. A property called “Price” could then represent the price of an item. When you create the Price property, you specify the data type, which in this case might be “Number”, indicating that this particular field accepts only numerical values. Consequently, you could also create a drop down list property called “Category”, allowing you to categorize the items in your price list. To add items to the drop down list, you modify the data type definition in the Developer module of the Umbraco administrative utility. Instead of modifying the drop down data type itself, you should first make a copy by right-clicking on the Data Types node and choosing Create. Give your new data type a name in the Create dialog and click the Create button. In the Edit datatype dialog, change “Render control” to “Dropdown list”.  To add your list items, simply enter that value into the textbox next to “Add prevalue” and click Save or press the Enter key. Now that you have a new drop down list data type created, along with assigned list items, you can use it in your document type definitions just like you would the other data types.

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  • C#/.NET Little Wonders: Tuples and Tuple Factory Methods

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can really help improve your code by making it easier to write and maintain.  This week, we look at the System.Tuple class and the handy factory methods for creating a Tuple by inferring the types. What is a Tuple? The System.Tuple is a class that tends to inspire a reaction in one of two ways: love or hate.  Simply put, a Tuple is a data structure that holds a specific number of items of a specific type in a specific order.  That is, a Tuple<int, string, int> is a tuple that contains exactly three items: an int, followed by a string, followed by an int.  The sequence is important not only to distinguish between two members of the tuple with the same type, but also for comparisons between tuples.  Some people tend to love tuples because they give you a quick way to combine multiple values into one result.  This can be handy for returning more than one value from a method (without using out or ref parameters), or for creating a compound key to a Dictionary, or any other purpose you can think of.  They can be especially handy when passing a series of items into a call that only takes one object parameter, such as passing an argument to a thread's startup routine.  In these cases, you do not need to define a class, simply create a tuple containing the types you wish to return, and you are ready to go? On the other hand, there are some people who see tuples as a crutch in object-oriented design.  They may view the tuple as a very watered down class with very little inherent semantic meaning.  As an example, what if you saw this in a piece of code: 1: var x = new Tuple<int, int>(2, 5); What are the contents of this tuple?  If the tuple isn't named appropriately, and if the contents of each member are not self evident from the type this can be a confusing question.  The people who tend to be against tuples would rather you explicitly code a class to contain the values, such as: 1: public sealed class RetrySettings 2: { 3: public int TimeoutSeconds { get; set; } 4: public int MaxRetries { get; set; } 5: } Here, the meaning of each int in the class is much more clear, but it's a bit more work to create the class and can clutter a solution with extra classes. So, what's the correct way to go?  That's a tough call.  You will have people who will argue quite well for one or the other.  For me, I consider the Tuple to be a tool to make it easy to collect values together easily.  There are times when I just need to combine items for a key or a result, in which case the tuple is short lived and so the meaning isn't easily lost and I feel this is a good compromise.  If the scope of the collection of items, though, is more application-wide I tend to favor creating a full class. Finally, it should be noted that tuples are immutable.  That means they are assigned a value at construction, and that value cannot be changed.  Now, of course if the tuple contains an item of a reference type, this means that the reference is immutable and not the item referred to. Tuples from 1 to N Tuples come in all sizes, you can have as few as one element in your tuple, or as many as you like.  However, since C# generics can't have an infinite generic type parameter list, any items after 7 have to be collapsed into another tuple, as we'll show shortly. So when you declare your tuple from sizes 1 (a 1-tuple or singleton) to 7 (a 7-tuple or septuple), simply include the appropriate number of type arguments: 1: // a singleton tuple of integer 2: Tuple<int> x; 3:  4: // or more 5: Tuple<int, double> y; 6:  7: // up to seven 8: Tuple<int, double, char, double, int, string, uint> z; Anything eight and above, and we have to nest tuples inside of tuples.  The last element of the 8-tuple is the generic type parameter Rest, this is special in that the Tuple checks to make sure at runtime that the type is a Tuple.  This means that a simple 8-tuple must nest a singleton tuple (one of the good uses for a singleton tuple, by the way) for the Rest property. 1: // an 8-tuple 2: Tuple<int, int, int, int, int, double, char, Tuple<string>> t8; 3:  4: // an 9-tuple 5: Tuple<int, int, int, int, double, int, char, Tuple<string, DateTime>> t9; 6:  7: // a 16-tuple 8: Tuple<int, int, int, int, int, int, int, Tuple<int, int, int, int, int, int, int, Tuple<int,int>>> t14; Notice that on the 14-tuple we had to have a nested tuple in the nested tuple.  Since the tuple can only support up to seven items, and then a rest element, that means that if the nested tuple needs more than seven items you must nest in it as well.  Constructing tuples Constructing tuples is just as straightforward as declaring them.  That said, you have two distinct ways to do it.  The first is to construct the tuple explicitly yourself: 1: var t3 = new Tuple<int, string, double>(1, "Hello", 3.1415927); This creates a triple that has an int, string, and double and assigns the values 1, "Hello", and 3.1415927 respectively.  Make sure the order of the arguments supplied matches the order of the types!  Also notice that we can't half-assign a tuple or create a default tuple.  Tuples are immutable (you can't change the values once constructed), so thus you must provide all values at construction time. Another way to easily create tuples is to do it implicitly using the System.Tuple static class's Create() factory methods.  These methods (much like C++'s std::make_pair method) will infer the types from the method call so you don't have to type them in.  This can dramatically reduce the amount of typing required especially for complex tuples! 1: // this 4-tuple is typed Tuple<int, double, string, char> 2: var t4 = Tuple.Create(42, 3.1415927, "Love", 'X'); Notice how much easier it is to use the factory methods and infer the types?  This can cut down on typing quite a bit when constructing tuples.  The Create() factory method can construct from a 1-tuple (singleton) to an 8-tuple (octuple), which of course will be a octuple where the last item is a singleton as we described before in nested tuples. Accessing tuple members Accessing a tuple's members is simplicity itself… mostly.  The properties for accessing up to the first seven items are Item1, Item2, …, Item7.  If you have an octuple or beyond, the final property is Rest which will give you the nested tuple which you can then access in a similar matter.  Once again, keep in mind that these are read-only properties and cannot be changed. 1: // for septuples and below, use the Item properties 2: var t1 = Tuple.Create(42, 3.14); 3:  4: Console.WriteLine("First item is {0} and second is {1}", 5: t1.Item1, t1.Item2); 6:  7: // for octuples and above, use Rest to retrieve nested tuple 8: var t9 = new Tuple<int, int, int, int, int, int, int, 9: Tuple<int, int>>(1,2,3,4,5,6,7,Tuple.Create(8,9)); 10:  11: Console.WriteLine("The 8th item is {0}", t9.Rest.Item1); Tuples are IStructuralComparable and IStructuralEquatable Most of you know about IComparable and IEquatable, what you may not know is that there are two sister interfaces to these that were added in .NET 4.0 to help support tuples.  These IStructuralComparable and IStructuralEquatable make it easy to compare two tuples for equality and ordering.  This is invaluable for sorting, and makes it easy to use tuples as a compound-key to a dictionary (one of my favorite uses)! Why is this so important?  Remember when we said that some folks think tuples are too generic and you should define a custom class?  This is all well and good, but if you want to design a custom class that can automatically order itself based on its members and build a hash code for itself based on its members, it is no longer a trivial task!  Thankfully the tuple does this all for you through the explicit implementations of these interfaces. For equality, two tuples are equal if all elements are equal between the two tuples, that is if t1.Item1 == t2.Item1 and t1.Item2 == t2.Item2, and so on.  For ordering, it's a little more complex in that it compares the two tuples one at a time starting at Item1, and sees which one has a smaller Item1.  If one has a smaller Item1, it is the smaller tuple.  However if both Item1 are the same, it compares Item2 and so on. For example: 1: var t1 = Tuple.Create(1, 3.14, "Hi"); 2: var t2 = Tuple.Create(1, 3.14, "Hi"); 3: var t3 = Tuple.Create(2, 2.72, "Bye"); 4:  5: // true, t1 == t2 because all items are == 6: Console.WriteLine("t1 == t2 : " + t1.Equals(t2)); 7:  8: // false, t1 != t2 because at least one item different 9: Console.WriteLine("t2 == t2 : " + t2.Equals(t3)); The actual implementation of IComparable, IEquatable, IStructuralComparable, and IStructuralEquatable is explicit, so if you want to invoke the methods defined there you'll have to manually cast to the appropriate interface: 1: // true because t1.Item1 < t3.Item1, if had been same would check Item2 and so on 2: Console.WriteLine("t1 < t3 : " + (((IComparable)t1).CompareTo(t3) < 0)); So, as I mentioned, the fact that tuples are automatically equatable and comparable (provided the types you use define equality and comparability as needed) means that we can use tuples for compound keys in hashing and ordering containers like Dictionary and SortedList: 1: var tupleDict = new Dictionary<Tuple<int, double, string>, string>(); 2:  3: tupleDict.Add(t1, "First tuple"); 4: tupleDict.Add(t2, "Second tuple"); 5: tupleDict.Add(t3, "Third tuple"); Because IEquatable defines GetHashCode(), and Tuple's IStructuralEquatable implementation creates this hash code by combining the hash codes of the members, this makes using the tuple as a complex key quite easy!  For example, let's say you are creating account charts for a financial application, and you want to cache those charts in a Dictionary based on the account number and the number of days of chart data (for example, a 1 day chart, 1 week chart, etc): 1: // the account number (string) and number of days (int) are key to get cached chart 2: var chartCache = new Dictionary<Tuple<string, int>, IChart>(); Summary The System.Tuple, like any tool, is best used where it will achieve a greater benefit.  I wouldn't advise overusing them, on objects with a large scope or it can become difficult to maintain.  However, when used properly in a well defined scope they can make your code cleaner and easier to maintain by removing the need for extraneous POCOs and custom property hashing and ordering. They are especially useful in defining compound keys to IDictionary implementations and for returning multiple values from methods, or passing multiple values to a single object parameter. Tweet Technorati Tags: C#,.NET,Tuple,Little Wonders

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  • Fun with Declarative Components

    - by [email protected]
    Use case background I have been asked on a number of occasions if our selectOneChoice component could allow random text to be entered, as well as having a list of selections available. Unfortunately, the selectOneChoice component only allows entry via the dropdown selection list and doesn't allow text entry. I was thinking of possible solutions and thought that this might make a good example for using a declarative component.My initial idea My first thought was to use an af:inputText to allow the text entry, and an af:selectOneChoice with mode="compact" for the selections. To get it to layout horizontally, we would want to use an af:panelGroupLayout with layout="horizontal". To get the label for this to line up correctly, we'll need to wrap the af:panelGroupLayout with an af:panelLabelAndMessage. This is the basic structure: <af:panelLabelAndMessage> <af:panelGroupLayout layout="horizontal"> <af:inputText/> <af:selectOneChoice mode="compact"/> </af:panelgroupLayout></af:panelLabelAndMessage> Make it into a declarative component One of the steps to making a declarative component is deciding what attributes we want to be able to specify. To keep this example simple, let's just have: 'label' (the label of our declarative component)'value' (what we want to bind to the value of the input text)'items' (the select items in our dropdown) Here is the initial declarative component code (saved as file "inputTextWithChoice.jsff"): <?xml version='1.0' encoding='UTF-8'?><!-- Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved. --><jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1" xmlns:f="http://java.sun.com/jsf/core" xmlns:af="http://xmlns.oracle.com/adf/faces/rich"> <jsp:directive.page contentType="text/html;charset=utf-8"/> <af:componentDef var="attrs" componentVar="comp"> <af:xmlContent> <component xmlns="http://xmlns.oracle.com/adf/faces/rich/component"> <description>Input text with choice component.</description> <attribute> <description>Label</description> <attribute-name>label</attribute-name> <attribute-class>java.lang.String</attribute-class> </attribute> <attribute> <description>Value</description> <attribute-name>value</attribute-name> <attribute-class>java.lang.Object</attribute-class> </attribute> <attribute> <description>Choice Select Items Value</description> <attribute-name>items</attribute-name> <attribute-class>[[Ljavax.faces.model.SelectItem;</attribute-class> </attribute> </component> </af:xmlContent> <af:panelLabelAndMessage id="myPlm" label="#{attrs.label}" for="myIt"> <af:panelGroupLayout id="myPgl" layout="horizontal"> <af:inputText id="myIt" value="#{attrs.value}" partialTriggers="mySoc" label="myIt" simple="true" /> <af:selectOneChoice id="mySoc" label="mySoc" simple="true" mode="compact" value="#{attrs.value}" autoSubmit="true"> <f:selectItems id="mySIs" value="#{attrs.items}" /> </af:selectOneChoice> </af:panelGroupLayout> </af:panelLabelAndMessage> </af:componentDef></jsp:root> By having af:inputText and af:selectOneChoice both have the same value, then (assuming that this passed in as an EL expression) selecting something in the selectOneChoice will update the value in the af:inputText. To use this declarative component in a jspx page: <af:declarativeComponent id="myItwc" viewId="inputTextWithChoice.jsff" label="InputText with Choice" value="#{demoInput.choiceValue}" items="#{demoInput.selectItems}" /> Some problems arise At first glace, this seems to be functioning like we want it to. However, there is a side effect to having the af:inputText and af:selectOneChoice share a value, if one changes, so does the other. The problem here is that when we update the af:inputText to something that doesn't match one of the selections in the af:selectOneChoice, the af:selectOneChoice will set itself to null (since the value doesn't match one of the selections) and the next time the page is submitted, it will submit the null value and the af:inputText will be empty. Oops, we don't want that. Hmm, what to do. Okay, how about if we make sure that the current value is always available in the selection list. But, lets not render it if the value is empty. We also need to add a partialTriggers attribute so that this gets updated when the af:inputText is changed. Plus, we really don't want to select this item so let's disable it. <af:selectOneChoice id="mySoc" partialTriggers="myIt" label="mySoc" simple="true" mode="compact" value="#{attrs.value}" autoSubmit="true"> <af:selectItem id="mySI" label="Selected:#{attrs.value}" value="#{attrs.value}" disabled="true" rendered="#{!empty attrs.value}"/> <af:separator id="mySp" /> <f:selectItems id="mySIs" value="#{attrs.items}" /></af:selectOneChoice> That seems to be working pretty good. One minor issue that we probably can't do anything about is that when you enter something in the inputText and then click on the selectOneChoice, the popup is displayed, but then goes away because it has been replaced via PPR because we told it to with the partialTriggers="myIt". This is not that big a deal, since if you are entering something manually, you probably don't want to select something from the list right afterwards. Making it look like a single component. Now, let's play around a bit with the contentStyle of the af:inputText and the af:selectOneChoice so that the compact icon will layout inside the af:inputText, making it look more like an af:selectManyChoice. We need to add some padding-right to the af;inputText so there is space for the icon. These adjustments were for the Fusion FX skin. <af:inputText id="myIt" partialTriggers="mySoc" autoSubmit="true" contentStyle="padding-right: 15px;" value="#{attrs.value}" label="myIt" simple="true" /><af:selectOneChoice id="mySoc" partialTriggers="myIt" contentStyle="position: relative; top: -2px; left: -19px;" label="mySoc" simple="true" mode="compact" value="#{attrs.value}" autoSubmit="true"> <af:selectItem id="mySI" label="Selected:#{attrs.value}" value="#{attrs.value}" disabled="true" rendered="#{!empty attrs.value}"/> <af:separator id="mySp" /> <f:selectItems id="mySIs" value="#{attrs.items}" /></af:selectOneChoice> There you have it, a declarative component that allows for suggested selections, but also allows arbitrary text to be entered. This could be used for search field, where the 'items' attribute could be populated with popular searches. Lines of java code written: 0

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  • C#/.NET Little Wonders: The Useful But Overlooked Sets

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  Today we will be looking at two set implementations in the System.Collections.Generic namespace: HashSet<T> and SortedSet<T>.  Even though most people think of sets as mathematical constructs, they are actually very useful classes that can be used to help make your application more performant if used appropriately. A Background From Math In mathematical terms, a set is an unordered collection of unique items.  In other words, the set {2,3,5} is identical to the set {3,5,2}.  In addition, the set {2, 2, 4, 1} would be invalid because it would have a duplicate item (2).  In addition, you can perform set arithmetic on sets such as: Intersections: The intersection of two sets is the collection of elements common to both.  Example: The intersection of {1,2,5} and {2,4,9} is the set {2}. Unions: The union of two sets is the collection of unique items present in either or both set.  Example: The union of {1,2,5} and {2,4,9} is {1,2,4,5,9}. Differences: The difference of two sets is the removal of all items from the first set that are common between the sets.  Example: The difference of {1,2,5} and {2,4,9} is {1,5}. Supersets: One set is a superset of a second set if it contains all elements that are in the second set. Example: The set {1,2,5} is a superset of {1,5}. Subsets: One set is a subset of a second set if all the elements of that set are contained in the first set. Example: The set {1,5} is a subset of {1,2,5}. If We’re Not Doing Math, Why Do We Care? Now, you may be thinking: why bother with the set classes in C# if you have no need for mathematical set manipulation?  The answer is simple: they are extremely efficient ways to determine ownership in a collection. For example, let’s say you are designing an order system that tracks the price of a particular equity, and once it reaches a certain point will trigger an order.  Now, since there’s tens of thousands of equities on the markets, you don’t want to track market data for every ticker as that would be a waste of time and processing power for symbols you don’t have orders for.  Thus, we just want to subscribe to the stock symbol for an equity order only if it is a symbol we are not already subscribed to. Every time a new order comes in, we will check the list of subscriptions to see if the new order’s stock symbol is in that list.  If it is, great, we already have that market data feed!  If not, then and only then should we subscribe to the feed for that symbol. So far so good, we have a collection of symbols and we want to see if a symbol is present in that collection and if not, add it.  This really is the essence of set processing, but for the sake of comparison, let’s say you do a list instead: 1: // class that handles are order processing service 2: public sealed class OrderProcessor 3: { 4: // contains list of all symbols we are currently subscribed to 5: private readonly List<string> _subscriptions = new List<string>(); 6:  7: ... 8: } Now whenever you are adding a new order, it would look something like: 1: public PlaceOrderResponse PlaceOrder(Order newOrder) 2: { 3: // do some validation, of course... 4:  5: // check to see if already subscribed, if not add a subscription 6: if (!_subscriptions.Contains(newOrder.Symbol)) 7: { 8: // add the symbol to the list 9: _subscriptions.Add(newOrder.Symbol); 10: 11: // do whatever magic is needed to start a subscription for the symbol 12: } 13:  14: // place the order logic! 15: } What’s wrong with this?  In short: performance!  Finding an item inside a List<T> is a linear - O(n) – operation, which is not a very performant way to find if an item exists in a collection. (I used to teach algorithms and data structures in my spare time at a local university, and when you began talking about big-O notation you could immediately begin to see eyes glossing over as if it was pure, useless theory that would not apply in the real world, but I did and still do believe it is something worth understanding well to make the best choices in computer science). Let’s think about this: a linear operation means that as the number of items increases, the time that it takes to perform the operation tends to increase in a linear fashion.  Put crudely, this means if you double the collection size, you might expect the operation to take something like the order of twice as long.  Linear operations tend to be bad for performance because they mean that to perform some operation on a collection, you must potentially “visit” every item in the collection.  Consider finding an item in a List<T>: if you want to see if the list has an item, you must potentially check every item in the list before you find it or determine it’s not found. Now, we could of course sort our list and then perform a binary search on it, but sorting is typically a linear-logarithmic complexity – O(n * log n) - and could involve temporary storage.  So performing a sort after each add would probably add more time.  As an alternative, we could use a SortedList<TKey, TValue> which sorts the list on every Add(), but this has a similar level of complexity to move the items and also requires a key and value, and in our case the key is the value. This is why sets tend to be the best choice for this type of processing: they don’t rely on separate keys and values for ordering – so they save space – and they typically don’t care about ordering – so they tend to be extremely performant.  The .NET BCL (Base Class Library) has had the HashSet<T> since .NET 3.5, but at that time it did not implement the ISet<T> interface.  As of .NET 4.0, HashSet<T> implements ISet<T> and a new set, the SortedSet<T> was added that gives you a set with ordering. HashSet<T> – For Unordered Storage of Sets When used right, HashSet<T> is a beautiful collection, you can think of it as a simplified Dictionary<T,T>.  That is, a Dictionary where the TKey and TValue refer to the same object.  This is really an oversimplification, but logically it makes sense.  I’ve actually seen people code a Dictionary<T,T> where they store the same thing in the key and the value, and that’s just inefficient because of the extra storage to hold both the key and the value. As it’s name implies, the HashSet<T> uses a hashing algorithm to find the items in the set, which means it does take up some additional space, but it has lightning fast lookups!  Compare the times below between HashSet<T> and List<T>: Operation HashSet<T> List<T> Add() O(1) O(1) at end O(n) in middle Remove() O(1) O(n) Contains() O(1) O(n)   Now, these times are amortized and represent the typical case.  In the very worst case, the operations could be linear if they involve a resizing of the collection – but this is true for both the List and HashSet so that’s a less of an issue when comparing the two. The key thing to note is that in the general case, HashSet is constant time for adds, removes, and contains!  This means that no matter how large the collection is, it takes roughly the exact same amount of time to find an item or determine if it’s not in the collection.  Compare this to the List where almost any add or remove must rearrange potentially all the elements!  And to find an item in the list (if unsorted) you must search every item in the List. So as you can see, if you want to create an unordered collection and have very fast lookup and manipulation, the HashSet is a great collection. And since HashSet<T> implements ICollection<T> and IEnumerable<T>, it supports nearly all the same basic operations as the List<T> and can use the System.Linq extension methods as well. All we have to do to switch from a List<T> to a HashSet<T>  is change our declaration.  Since List and HashSet support many of the same members, chances are we won’t need to change much else. 1: public sealed class OrderProcessor 2: { 3: private readonly HashSet<string> _subscriptions = new HashSet<string>(); 4:  5: // ... 6:  7: public PlaceOrderResponse PlaceOrder(Order newOrder) 8: { 9: // do some validation, of course... 10: 11: // check to see if already subscribed, if not add a subscription 12: if (!_subscriptions.Contains(newOrder.Symbol)) 13: { 14: // add the symbol to the list 15: _subscriptions.Add(newOrder.Symbol); 16: 17: // do whatever magic is needed to start a subscription for the symbol 18: } 19: 20: // place the order logic! 21: } 22:  23: // ... 24: } 25: Notice, we didn’t change any code other than the declaration for _subscriptions to be a HashSet<T>.  Thus, we can pick up the performance improvements in this case with minimal code changes. SortedSet<T> – Ordered Storage of Sets Just like HashSet<T> is logically similar to Dictionary<T,T>, the SortedSet<T> is logically similar to the SortedDictionary<T,T>. The SortedSet can be used when you want to do set operations on a collection, but you want to maintain that collection in sorted order.  Now, this is not necessarily mathematically relevant, but if your collection needs do include order, this is the set to use. So the SortedSet seems to be implemented as a binary tree (possibly a red-black tree) internally.  Since binary trees are dynamic structures and non-contiguous (unlike List and SortedList) this means that inserts and deletes do not involve rearranging elements, or changing the linking of the nodes.  There is some overhead in keeping the nodes in order, but it is much smaller than a contiguous storage collection like a List<T>.  Let’s compare the three: Operation HashSet<T> SortedSet<T> List<T> Add() O(1) O(log n) O(1) at end O(n) in middle Remove() O(1) O(log n) O(n) Contains() O(1) O(log n) O(n)   The MSDN documentation seems to indicate that operations on SortedSet are O(1), but this seems to be inconsistent with its implementation and seems to be a documentation error.  There’s actually a separate MSDN document (here) on SortedSet that indicates that it is, in fact, logarithmic in complexity.  Let’s put it in layman’s terms: logarithmic means you can double the collection size and typically you only add a single extra “visit” to an item in the collection.  Take that in contrast to List<T>’s linear operation where if you double the size of the collection you double the “visits” to items in the collection.  This is very good performance!  It’s still not as performant as HashSet<T> where it always just visits one item (amortized), but for the addition of sorting this is a good thing. Consider the following table, now this is just illustrative data of the relative complexities, but it’s enough to get the point: Collection Size O(1) Visits O(log n) Visits O(n) Visits 1 1 1 1 10 1 4 10 100 1 7 100 1000 1 10 1000   Notice that the logarithmic – O(log n) – visit count goes up very slowly compare to the linear – O(n) – visit count.  This is because since the list is sorted, it can do one check in the middle of the list, determine which half of the collection the data is in, and discard the other half (binary search).  So, if you need your set to be sorted, you can use the SortedSet<T> just like the HashSet<T> and gain sorting for a small performance hit, but it’s still faster than a List<T>. Unique Set Operations Now, if you do want to perform more set-like operations, both implementations of ISet<T> support the following, which play back towards the mathematical set operations described before: IntersectWith() – Performs the set intersection of two sets.  Modifies the current set so that it only contains elements also in the second set. UnionWith() – Performs a set union of two sets.  Modifies the current set so it contains all elements present both in the current set and the second set. ExceptWith() – Performs a set difference of two sets.  Modifies the current set so that it removes all elements present in the second set. IsSupersetOf() – Checks if the current set is a superset of the second set. IsSubsetOf() – Checks if the current set is a subset of the second set. For more information on the set operations themselves, see the MSDN description of ISet<T> (here). What Sets Don’t Do Don’t get me wrong, sets are not silver bullets.  You don’t really want to use a set when you want separate key to value lookups, that’s what the IDictionary implementations are best for. Also sets don’t store temporal add-order.  That is, if you are adding items to the end of a list all the time, your list is ordered in terms of when items were added to it.  This is something the sets don’t do naturally (though you could use a SortedSet with an IComparer with a DateTime but that’s overkill) but List<T> can. Also, List<T> allows indexing which is a blazingly fast way to iterate through items in the collection.  Iterating over all the items in a List<T> is generally much, much faster than iterating over a set. Summary Sets are an excellent tool for maintaining a lookup table where the item is both the key and the value.  In addition, if you have need for the mathematical set operations, the C# sets support those as well.  The HashSet<T> is the set of choice if you want the fastest possible lookups but don’t care about order.  In contrast the SortedSet<T> will give you a sorted collection at a slight reduction in performance.   Technorati Tags: C#,.Net,Little Wonders,BlackRabbitCoder,ISet,HashSet,SortedSet

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  • Calculating 2D (screen) coordinates from 3D positions in XNA 4.0

    - by NDraskovic
    I have a program that draws some items to the scene by loading their positions from a file. Now I want to place a Ray on the same location where the items are drawn. So my question is how can I calculate the position of the ray (it's 2D components) by using 3D coordinates of each particular item? The items don't move anywhere, so once they are placed they stay until the end of the programs execution. Thanks.

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  • Creating collection with no code (almost)

    - by Sean Feldman
    When doing testing, I tend to create an object mother for the items generated multiple times for specifications. Quite often these objects need to be a part of a collection. A neat way to do so is to leverage .NET params mechanism: public static IEnumerable<T> CreateCollection<T>(params T[] items) { return items; } And usage is the following: private static IEnumerable<IPAddress> addresses = CreateCollection(new IPAddress(123456789), new IPAddress(987654321));

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  • Usage of repository between EF model and code consumer

    - by jim
    I have binary data in my database that I'll have to convert to bitmap at some point. I was thinking whether or not it's appropriate to use a repository and do it there. My consumer, which is a presentation layer, will use this repository. For example: // This is a class I created for modeling the item as is. public class RealItem { public string Name { get; set; } public Bitmap Image { get; set; } } public abstract class BaseRepository { //using Unity (http://unity.codeplex.com) to inject the dependancy of entity context. [Dependency] public Context { get; set; } } public calss ItemRepository : BaseRepository { public List<Items> Select() { IEnumerable<Items> items = from item in Context.Items select item; List<RealItem> lst = new List<RealItem>(); foreach(itm in items) { MemoryStream stream = new MemoryStream(itm.Image); Bitmap image = (Bitmap)Image.FromStream(stream); RealItem ritem = new RealItem{ Name=item.Name, Image=image }; lst.Add(ritem); } return lst; } } Is this a correct way to use the repository pattern? I'm learning this pattern and I've seen a lot of examples online that are using a repository but when I looked at their source code... for example: public IQueryable<object> Select { return from q in base.Context select q; } as you can see no behavior is added to the system by their approach, so I was confused that maybe repository is something else and I got it all wrong. At the end there should be extra benifits of using them right?

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  • How to manage long running background threads and report progress with DDD

    - by Mr Happy
    Title says most of it. I have found surprising little information about this. I have a long running operation of which the user wants to see the progress (as in, item x of y processed). I also need to be able to pause and stop the operation. (Stopping doesn't rollback the items already processed.) The thing is, it's not that each item takes a long time to get processed, it's that that there are usually a lot of items. And what I've read about so far is that it's somewhat of an anti-pattern to put something like a queue in the DB. I currently don't have any messaging system in place, and I've never worked with one either. Another thing I read somewhere is that progress reporting is something that belongs in the application layer, but it didn't go into the details. So having said all this, what I have in mind is the following. User request with list of items enters the application layer. Application layer gets some information from the domain needed to process the items. Application layer passes the items and the information off to some domain service (should the implementation of this service belong in the infrastructure layer?) This service spins up a worker thread with callbacks for both progress reporting and pausing/stopping it. This worker thread will process each item in it's own UoW. This means the domain information from earlier needs to be stored in some DTO. Since nothing is really persisted, the service should be singleton and thread safe Whenever a user requests a progress report or wants to pause/stop the operation, the application layer will ask the service. Would this be a correct solution? Or am I at least on the right track with this? Especially the singleton and thread safe part makes the whole thing feel icky.

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  • Announcing Key Functional White Papers for SIM and ReIM

    - by Oracle Retail Documentation Team
    Oracle Retail has published two new documents on My Oracle Support (https://support.oracle.com)  that provide partners and retailers with deeper functional information about two products: Oracle Retail Store Inventory Management (SIM) and Oracle Retail Invoice Matching. Oracle Retail Store Inventory Management Item Configuration White Paper (Doc ID 1507221.1) There is functionality within the Store Inventory Management system related to item configuration that spans across multiple concepts that apply to the application as a whole rather than to a specific area. This white paper covers numerous topics around item configuration including: Item Transaction Levels Item Long Description Pack Size Standard Unit of Measure Standard Unit of Measure Conversion Pack Items Simple Pack Conversion Items (Notional Packs) Ranging Items Item Status Non-Sellable Items Type-2 Item Recognition UPC-E Barcodes Non-Inventory Items Consignment and Concession Items Quick Response Codes Oracle Retail Invoice Matching Financial Transactions (Doc ID 1500209.1) This document explains the financial transactions that are posted by Oracle Retail Invoice Matching (ReIM). The scope of the document is limited to ReIM transactions only, and does not explain Retail Merchandising System (RMS), Finance, or Account Receivable transactions. ReIM follows the double-entry accounting standard, which works by recording the debit and credit of each financial transaction belonging to each party involved. Each transaction means a profit to one account (debit) and a loss to another account (credit). Full invoice match processing is completed in ReIM with payment recommendations communicated to Oracle Accounts Payable. ReIM matches merchandise orders and receipts against merchandise invoices, performing automated and manual matching, as well as discrepancy-resolution processing. Matched invoices are posted to interface staging tables specifying the amount and date to pay, vendor, site ID, General Ledger Chart of Accounts (GL CoA) information, and payment terms. Other payables documents, including debit memos, credit memos and credit notes are also interfaced to Accounts Payable through the ReIM staging tables (IM_AP_STAGE_HEAD and IM_AP_STAGE_DETAIL). For information about how ReIM engages in this processing, see the latest Oracle Retail Invoice Matching Operations Guide. Certain ReIM transactions are not interfaced to Oracle Payables, but instead are interfaced to Oracle General Ledger through the IM_FINANCIAL_STAGE table. When analyzing transactions posted through the staging tables, retailers should note the transaction type, Standard/Credit, as well as the sign in the amount field. Technically, a negative sign on a credit transaction changes the transaction to a debit entry, and vice versa. This document is concerned about the financial meaning of the transactions, and will avoid a discussion of negative numbers in T-charts.

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  • Connect Digest : 2011-03-12

    - by AaronBertrand
    Background Last year, I came to a very tough decision that I would cease publicizing Connect items in an attempt to drive up votes and get important issues fixed. This was almost entirely due to a couple of MVPs criticizing me for raising awareness of certain Connect items instead of letting them be found "naturally." I wasn't sure what world they were living in, where droves of everyday end users just happened to stumble upon Connect items without any prompting. I suppose it could be said that the...(read more)

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  • WPF Release History : Q1 2010 SP1 (version 2010.1.0422)

    Q1 2010 SP1 Changes: RadGrid Important Changes: The enumerator of RadGridView.Items now enumerates data items only (use RadGridView.Items.Groups to retrieve group items). What's New: Added support for BorderBrush and BorderThickness for GridViewRow. Editable field filter logical composition operator (And/Or). New overload of the GridViewDataContro.GetDistinctValues method that accepts the number of distinct values to return as a parameter. Group footer row now uses its Item as aggregate...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Design difficulty for multiple panel forms [closed]

    - by petre
    I have form that consists of multiple panel on the right, a treeview on the left and a terminal richtextbox on the bottom. When i click on a node of the treeview i bring up the panel that is attached with the node. For example i have 10 nodes on the treeview, i have 10 panels that are attached to this nodes. On every panel, i have many textboxes, labels, comboboxes etc. I don't dynamically construct and dispose the items on the panels, i create the items in the designer file of the project. In that case, there is a problem. I really find it difficult to align or place items on the panel because there seems a lot of aligning lines on the screen. What should be done to make the design of the panels easy? I don't want to construct items dynamically. Do i have to do that dynamically or is there a design procedure that make this process easy?

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  • Checking For Empty Enumerations

    While spelunking in some code recently I saw a method that looked something like this: public void Foo<T>(IEnumerable<T> items) { if(items == null || items.Count() == 0) { // Warn about emptiness } } This method accepts a generic enumeration and then proceeds to check if the enumeration is null or empty. Do you see the potential problem with this code? Ill give you a hint, its this line: items.Count() == 0 Whats the problem? Well that line right there has the potential...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • SkyDrive Pro Limits

    - by Sahil Malik
    SharePoint 2010 Training: more information I’m putting this here, because I know I’m gonna forget it :) Overall size limits - On an on premises installation, there are no fixed limits on storage. You can configure it as you wish. For Office 365 (SharePoint Online), the limit is 7GB per user. Number of items (documents and folders): You can sync up to 20,000 items in your SkyDrive (personal library). You can sync up to 5,000 items from other libraries, per library. In other words, you could sync 10 libraries (for example), with each library having up to 5000 items. Third, site limits: No fixed limits. It depends on your computer's resources. Hooray! and Happy SharePointing! Read full article ....

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  • Why does Outlook 2010 give the message "Creating a new item from the selected items could take some time...are you sure you create a new item...?

    - by Matt
    I'm using Outlook 2010 with Exchange 2007. I am moving emails from my Deleted Items folder to a user-created folder. When I move a "low" number of messages, say a few hundred or less, the operation completes successfully. When I move a "large" number of messages (in this example it's over 800) I get the message shown in the screenshot below. If I click Yes, a new email is generated and has links to all the emails I selected in the Attachment field. When I cancel that email, not only have the messages not moved but they appear to be deleted entirely. What does the message mean and why does it get presented? Why does clicking Yes do the behavior I described above?

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  • Collapsible menu and amount of links in a web page

    - by dstonek
    One of my pages contain three levels of a collapsible menu (JS + CSS from mycssmenu.com). There are a dozen first level items displayed to users, each one with various second level items, and finally a lot of third level items, each one containing a related link. This generates a lot of internal links (300+). Because of SEO should I change the way the collapsible menu is displayed to reduce link amount? What do you suggest? I would like to avoid users to have to open a new page just to only see what are third level items and eventually follow one of its links.

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  • How to do lazy loading in a SOA fashion?

    - by sun1991
    For example, I've got a root object exposed in a SOA service, say Invoice (Invoice has line items as children). Sometimes, I need to retrieve its detail line items. I'm thinking to make it lazy loading, because it's a traffic overhead to transfer line items every time Invoice is required. But in SOA fashion, it seems unlikely. Because all it can expose are Invoice POCOs, with contain no logic. Thus I cannot attach my lazy loading logic to Invoice to instruct it to load lines items when needed.

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  • Split up a screen into regions

    - by nexen
    My task: I want to split up a screen into 3 regions for buffs-bar (with picked items), score-info and a game-map. It doesn't matter are regions intersect with each other or not. For example: I have a screen with width=1; height=1 and the origin of coordinates (0;0) is the left bottom point. I have 3 functions: draw items, draw info, draw map. If I use it without any matrix transformations, it draws fullscreen, because it's vertex coordinates are from 0;0 to 1;1. (pseudo-code) drawItems(); drawInfo(); drawMap(); And after that I see only map onto info onto items. My goal: I have some matrixes for transformation vertexes with 0;0-1;1 coordinates to strict regions. There is only one thing, what I need to do - set matrix before drawing. So my call of drawItems-function is like: (pseudo-code) adjustViewMatrixes_andSomethingElse(items.position_of_the_region_there_it_should_be_drawn, items.sizes_of_region_to_draw); setItemsMatrix(); drawItems(); //the same function with vertex coordinates 0;0->1;1, //but it draws in other coordinates, //because I have just set the matrix for region I know only some people will understand me, so there is a picture with regions which I need to make. Every region has 0;0 - 1;1 inner coordinates.

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  • Silverlight 4 minor update&ndash;June 2010

    Today we released a service update for Silverlight 4. This is a minor release that addresses some items found immediately after release that have now completed our test passes with those who reported them. Most of the items found wont affect all users, but media developers will want to get this update for their applications and encourage their users to upgrade. This update (4.0.50524.0) addresses a few media-related items found by some of our media customers. A few items were serviced for DRM users...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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