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  • Diagnosing problem with running ASP.NET app as 64-bit

    - by user54064
    I need to run an ASP.NET app as 64-bit. The app is quite large and has MANY assemblies to load. When I run it I am getting "is not a valid Win32 application" error in the web page as soon as I go to the first page. That page is a very simple "Hello World" page. However, it must be having problem with loading assemblies as 64-bit. How can I figure out which one(s) are the problem?

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  • what's an easier rampup: ASP.net or WCF?

    - by Greg
    Hi I'm across winforms currently but want to write an app that users will have a LAN/WAN between them and database. So assuming I need to use WCF if I stick with winforms as the UI, or go ASP.net and go web, THEN which of these two approaches would be the easier rampup approach for me? Note wanted to use Entity Framework.

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  • ASP.NET Security Exception

    - by Neo1975
    I moved an ASP.NET application from a XP to a new server and now I have this exception: 'System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, On this line code: System.Threading.Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo("it-IT"); My server is so configurated: Windows XP 2003 Sever SharePoint MS Visual Studio 2008 Team System Workgroup Server I tried to change security setting, machine.config. Someone can help me explain me where and how to change what? Thanks a lot.

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  • how to close a sqlconnection in asp.net

    - by stighy
    Hi guys, i would like to know if there's something wrong in this asp.net code: mydatareader = mycmd.executeReader() if myDataReader.HasRow then // Do something end if myConnection.Close() If i avoid to call a "MyDataReader.Close()" does the connection close anyway ? I ask this because i'm assuming that if call a "MyConn.Close" it automatically close the associated datareader... or am i wrong ? Thanks

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  • ASP.NET Ajax REST service not defined

    - by Attilah
    I created an ASP.NET REST service (using WCF) and access it through one of my .aspx page. the problem is that when I publish (precomile) my code to the web server, I get an error : "ThunServ not defined" in the Javascript console of my browser. don't know what's causing it and how to solve it.

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  • Maintain state of an ASP.NET page

    - by user279521
    Hi, what is your preferred method to maintain state of an asp.net page, if it is a public website (involving shopping cart, wish-list etc). I am in the process of designing a website that will need to ensure that the user is not able to tamper with the state (such as delete cookies etc).

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  • Inflector for .NET

    - by srkirkland
    I was writing conventions for FluentNHibernate the other day and I ran into the need to pluralize a given string and immediately thought of the ruby on rails Inflector.  It turns out there is a .NET library out there also capable of doing word inflection, originally written (I believe) by Andrew Peters, though the link I had no longer works.  The entire Inflector class is only a little over 200 lines long and can be easily included into any project, and contains the Pluralize() method along with a few other helpful methods (like Singularize(), Camelize(), Capitalize(), etc). The Inflector class is available in its entirety from my github repository https://github.com/srkirkland/Inflector.  In addition to the Inflector.cs class I added tests for every single method available so you can gain an understanding of what each method does.  Also, if you are wondering about a specific test case feel free to fork my project and add your own test cases to ensure Inflector does what you expect. Here is an example of some test cases for pluralize: TestData.Add("quiz", "quizzes"); TestData.Add("perspective", "perspectives"); TestData.Add("ox", "oxen"); TestData.Add("buffalo", "buffaloes"); TestData.Add("tomato", "tomatoes"); TestData.Add("dwarf", "dwarves"); TestData.Add("elf", "elves"); TestData.Add("mouse", "mice");   TestData.Add("octopus", "octopi"); TestData.Add("vertex", "vertices"); TestData.Add("matrix", "matrices");   TestData.Add("rice", "rice"); TestData.Add("shoe", "shoes"); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Pretty smart stuff.

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  • Design pattern for an ASP.NET project using Entity Framework

    - by MPelletier
    I'm building a website in ASP.NET (Web Forms) on top of an engine with business rules (which basically resides in a separate DLL), connected to a database mapped with Entity Framework (in a 3rd, separate project). I designed the Engine first, which has an Entity Framework context, and then went on to work on the website, which presents various reports. I believe I made a terrible design mistake in that the website has its own context (which sounded normal at first). I present this mockup of the engine and a report page's code behind: Engine (in separate DLL): public Engine { DatabaseEntities _engineContext; public Engine() { // Connection string and procedure managed in DB layer _engineContext = DatabaseEntities.Connect(); } public ChangeSomeEntity(SomeEntity someEntity, int newValue) { //Suppose there's some validation too, non trivial stuff SomeEntity.Value = newValue; _engineContext.SaveChanges(); } } And report: public partial class MyReport : Page { Engine _engine; DatabaseEntities _webpageContext; public MyReport() { _engine = new Engine(); _databaseContext = DatabaseEntities.Connect(); } public void ChangeSomeEntityButton_Clicked(object sender, EventArgs e) { SomeEntity someEntity; //Wrong way: //Get the entity from the webpage context someEntity = _webpageContext.SomeEntities.Single(s => s.Id == SomeEntityId); //Send the entity from _webpageContext to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context //Right(?) way: //Get the entity from the engine context someEntity = _engine.GetSomeEntity(SomeEntityId); //undefined above //Send the entity from the engine's context to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context } } Because the webpage has its own context, giving the Engine an entity from a different context will cause an error. I happen to know not to do that, to only give the Engine entities from its own context. But this is a very error-prone design. I see the error of my ways now. I just don't know the right path. I'm considering: Creating the connection in the Engine and passing it off to the webpage. Always instantiate an Engine, make its context accessible from a property, sharing it. Possible problems: other conflicts? Slow? Concurrency issues if I want to expand to AJAX? Creating the connection from the webpage and passing it off to the Engine (I believe that's dependency injection?) Only talking through ID's. Creates redundancy, not always practical, sounds archaic. But at the same time, I already recuperate stuff from the page as ID's that I need to fetch anyways. What would be best compromise here for safety, ease-of-use and understanding, stability, and speed?

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  • Updating with using custom class collection not working

    - by Risho
    I've posted this yesterday on asp forum but no one replied so perhaps I'll have better luck here. For some reason the OnUpdating method does not pull new values from the grid which is in edit mode. I've search and have come across several blogs and sites, some sugesting that an ObjectDataSource is required in order to use the "e.NewValue" construct others provide code to the contrary. I don't get any errors - the variables in the code file would contain the old values rather then new ones. I don't want to use the ODS way of manipulating the data. My delete method works but not the update one. Can you suggest what is wrong with the code? Here is what I've got: aspx file: <asp:GridView ID="gvBlack" runat="server" AutoGenerateColumns="False" OnRowUpdating="gvBlack_OnUpdating" OnRowEditing="gvBlack_RowEditing"> <Columns> <%--<asp:BoundField DataField="Ident_Black" ReadOnly="True" visible="false" />--%> <asp:TemplateField ItemStyle-Width="1px"> <EditItemTemplate> <asp:Label ID="lblIdent_Black" runat="server" Text='<%# Bind("Ident_Black") %>' Visible="false" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Model" > <ItemTemplate> <asp:Label ID="lblModel_Black" runat="server" Text='<%# Bind("Model_Black") %>' width="130px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtModel_Black" runat="server" Text='<%# Eval("Model_Black") %>' width="100px" /> <asp:RequiredFieldValidator ID="rfvModel_Black" runat="server" ControlToValidate="txtModel_Black" SetFocusOnError="true" ErrorMessage="*" ValidationGroup="CurrentMfg" ForeColor="Red" Font-Bold="true" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Description" > <ItemTemplate> <asp:Label ID="lblDesc_Black" runat="server" Text='<%# Bind("Desc_Black") %>' width="200px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtDesc_Black" runat="server" Text='<%# Eval("Desc_Black") %>' width="170px" /> <span></span> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Qty" > <ItemTemplate> <asp:Label ID="lblQty_Black" runat="server" Text='<%# Bind("Qty_Black") %>' width="35px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtQty_Black" runat="server" Text='<%# Eval("Qty_Black") %>' width="35px" /> <asp:RequiredFieldValidator ID="rfvQty_Black" runat="server" ControlToValidate="txtQty_Black" SetFocusOnError="true" ErrorMessage="*" ValidationGroup="CurrentMfg" ForeColor="Red" Font-Bold="true" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Reorder<br />Limit"> <ItemTemplate> <asp:Label ID="lblBlack_Reorder_Limit" runat="server" Text='<%# Bind("Black_Reorder_Limit") %>' width="35px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtBlack_Reorder_Limit" runat="server" Text='<%# Eval("Black_Reorder_Limit") %>' width="35px" /> <asp:RequiredFieldValidator ID="rfvBlack_Reorder_Limit" runat="server" ControlToValidate="txtBlack_Reorder_Limit" SetFocusOnError="true" ErrorMessage="*" ValidationGroup="CurrentMfg" ForeColor="Red" Font-Bold="true" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Notes"> <ItemTemplate> <asp:Label ID="lblNotes" runat="server" Text='<%# Bind("Notes") %>' width="200px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtNotes" runat="server" Text='<%# Eval("Notes") %>' width="170px" /> <span></span> </EditItemTemplate> </asp:TemplateField> <asp:CommandField ShowEditButton="True" ShowDeleteButton="false" ValidationGroup="CurrentToner" /> </Columns> </asp:GridView> aspx.cs file: protected void Page_Load(object sender, EventArgs e) { LoadData_TonerBlack(); } private void LoadData_TonerBlack() { dalConsumables_TonerBlack drTonerBlack = new dalConsumables_TonerBlack(); gvBlack.DataSource = drTonerBlack.GetListTonersBlack(); gvBlack.DataBind(); } protected void gvBlack_OnUpdating(object sender, GridViewUpdateEventArgs e) { //GridView gvBlack = (GridView)sender; //GridViewRow gvBlackRow = (GridViewRow)gvBlack.Rows[e.RowIndex]; int _Ident_Black = Convert.ToInt32(gvBlack.DataKeys[e.RowIndex].Values[0].ToString()); TextBox _txtModel_Black = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtModel_Black"); TextBox _txtDesc_Black = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtDesc_Black"); TextBox _txtQty_Black = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtQty_Black"); TextBox _txtBlack_Reorder_Limit = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtBlack_Reorder_Limit"); TextBox _txtNotes = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtNotes"); string _updatedBy = Request.ServerVariables["AUTH_USER"].ToString(); dalConsumables_TonerBlack updateTonerBlack = new dalConsumables_TonerBlack(); updateTonerBlack.UpdateTonerBlack(_Ident_Black, _txtModel_Black.Text, _txtDesc_Black.Text, Convert.ToInt32(_txtQty_Black.Text), Convert.ToInt32(_txtBlack_Reorder_Limit.Text), _txtNotes.Text, _updatedBy); gvBlack.EditIndex = -1; LoadData_TonerBlack(); } protected void gvBlack_RowEditing(object sender, GridViewEditEventArgs e) { gvBlack.EditIndex = e.NewEditIndex; LoadData_TonerBlack(); } Thanks in advance! Risho

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  • ASP.Net Forms authentication provider issue

    - by George2
    Hello everyone, I am using VSTS 2008 + .Net 3.5 + ASP.Net to develop a simple web application. And I am using Forms authentication for my web site (I use command aspnet_regsql.exe to create a new database in SQL Server 2008 Enterprise to host database for Forms Authentication. I am not using SQL Server Express.). I am learning Forms authentication from here, http://msdn.microsoft.com/en-us/library/ff648345.aspx#paght000022_usingthesqlmembershipprovider my question is for the name of membership defaultProvider, the value must be "SqlProvider"? Or I can use any arbitrary name, for example like this (I replace the value "SqlProvider" to "MyTestSqlProvider")? <connectionStrings> <add name="MySqlConnection" connectionString="Data Source=MySqlServer;Initial Catalog=aspnetdb;Integrated Security=SSPI;" /> </connectionStrings> <system.web> ... <membership defaultProvider="MyTestSqlProvider" userIsOnlineTimeWindow="15"> <providers> <clear /> <add name="MyTestSqlProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="MySqlConnection" applicationName="MyApplication" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="true" requiresUniqueEmail="true" passwordFormat="Hashed" /> </providers> </membership> thanks in advance, George

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  • import csv file/excel into sql database asp.net

    - by kiev
    Hi everyone! I am starting a project with asp.net visual studio 2008 / SQL 2000 (2005 in future) using c#. The tricky part for me is that the existing DB schema changes often and the import files columns will all have to me matched up with the existing db schema since they may not be one to one match on column names. (There is a lookup table that provides the tables schema with column names I will use) I am exploring different ways to approach this, and need some expert advice. Is there any existing controls or frameworks that I can leverage to do any of this? So far I explored FileUpload .NET control, as well as some 3rd party upload controls to accomplish the upload such as SlickUpload but the files uploaded should be < 500mb Next part is reading of my csv /excel and parsing it for display to the user so they can match it with our db schema. I saw CSVReader and others but for excel its more difficult since I will need to support different versions. Essentially The user performing this import will insert and/or update several tables from this import file. There are other more advance requirements like record matching but and preview of the import records, but I wish to get through understanding how to do this first. Update: I ended up using csvReader with LumenWorks.Framework for uploading the csv files.

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  • 'Microsoft.Practices.EnterpriseLibrary.Caching.CacheFactory' threw an exception

    - by user281180
    Hi I`m having the error message: The type initializer for 'Microsoft.Practices.EnterpriseLibrary.Caching.CacheFactory' threw an exception. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Practices.ObjectBuilder2, Version=2.2.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified. Source Error: Line 30: private static ICacheManager GetCacheManager() Line 31: { Line 32: return CacheFactory.GetCacheManager(cacheManagerName); Line 33: } Line 34: } Source File: C:\Dev\DEV\HotHouse\HotHousetest3_rtmClone107\Code\MvcUI\State\PersistentCache.cs Line: 32 Assembly Load Trace: The following information can be helpful to determine why the assembly 'Microsoft.Practices.ObjectBuilder2, Version=2.2.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' could not be loaded. , whereas my colleages using the same dll, are not having the error message. Help please. I have Microsoft.Practices.EnterpriseLibrary.Caching and Microsoft.Practices.EnterpriseLibrary.Common as references both version 4.1.0.0 and runtime version v2.0.50727.

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  • Consuming a PHP SOAP WebService with ASP.NET

    - by Jamie
    I'm having some major issues trying to consume my PHP SOAP webservice using ASP.NET. The webservice in question is based on the PHP SOAP extension and is descibed by the following WSDL: <?xml version="1.0" encoding="UTF-8" ?> <definitions name="MyServices" targetNamespace="http://mydomain.com/api/soap/v11/services" xmlns:tns="http://mydomain.com/api/soap/v11/services" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsd1="http://mydomain.com/api/soap/v11/services" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns="http://schemas.xmlsoap.org/wsdl/"> <types> <schema targetNamespace="http://mydomain.com/api/soap/v11/services" xmlns="http://www.w3.org/2001/XMLSchema"> <complexType name="ServiceType"> <all> <element name="id" type="xsd:int" minOccurs="1" maxOccurs="1" /> <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1" /> <element name="cost" type="xsd:float" minOccurs="1" maxOccurs="1" /> </all> </complexType> <complexType name="ArrayOfServiceType"> <all> <element name="Services" type="ServiceType" minOccurs="0" maxOccurs="unbounded" /> </all> </complexType> </schema> </types> <message name="getServicesRequest"> <part name="postcode" type="xsd:string" /> </message> <message name="getServicesResponse"> <part name="Result" type="xsd1:ArrayOfServiceType"/> </message> <portType name="ServicesPortType"> <operation name="getServices"> <input message="tns:getServicesRequest"/> <output message="tns:getServicesResponse"/> </operation> </portType> <binding name="ServicesBinding" type="tns:ServicesPortType"> <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/> <operation name="getServices"> <soap:operation soapAction="http://mydomain.com/api/soap/v11/services/getServices" /> <input> <soap:body use="encoded" namespace="urn:my:services" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" /> </input> <output> <soap:body use="encoded" namespace="urn:my:services" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" /> </output> </operation> </binding> <service name="MyServices"> <port name="ServicesPort" binding="tns:ServicesBinding"> <soap:address location="http://mydomain.com/api/soap/v11/services"/> </port> </service> </definitions> I can successfully generate a proxy class from this WSDL in Visual Studio, but upon trying to invoke the getServices method I am presented with an exception: System.Web.Services.Protocols.SoapHeaderException: Procedure 'string' not present After inspecting the raw post data at the SOAP server end, my PHP SOAP client is making requests like this: <?xml version="1.0" encoding="UTF-8"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP-ENV:Body> <postcode xsi:type="xsd:string">ln4 4nq</postcode> </SOAP-ENV:Body> </SOAP-ENV:Envelope> Whereas the .Net proxy class is doing this: <?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:tns="http://mydomain.com/api/soap/v11/services" xmlns:types="http://mydomain.com/api/soap/v11/services/encodedTypes" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <soap:Body soap:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <xsd:string xsi:type="xsd:string">LN4 4NQ</xsd:string> </soap:Body> </soap:Envelope> I can only assume the difference in the way the postcode parameter is being sent is where the problem lies, but as primarily a PHP developer I'm at a loss as to what's occuring here. I have a feeling I'm simply missing something vital in my WSDL as I've seen countless examples of 'Consuming PHP SOAP WebServices with .Net' which appear to suggest that it 'just works'. Any suggestion as to where i've slipped up here would be greatly appreciated. I've currently spent almost an entire day on this now ;-) Thanks in advance, Jamie

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  • Unable to regress web application from AJAX Control Toolkit 3.0 back to 1.0

    - by David Neale
    I was recently asked to stop using the Ajax Control Toolkit 3.0 in my application and need to go back to 1.0. Luckily I only have one calendar control which I don't believe will be affected by this. I have removed the reference to the 3.0 .dll and added a reference to the 1.0 .dll. These are the assemblies in web.config: <assemblies> <add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/> <add assembly="System.Data.DataSetExtensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/> <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/> <add assembly="System.Web.Extensions.Design, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/> <add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/></assemblies> and this also also there: <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <dependentAssembly> <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/> <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/> </dependentAssembly> <dependentAssembly> <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/> <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/> </dependentAssembly> </assemblyBinding> </runtime> I get a compile error of: Could not load file or assembly 'AjaxControlToolkit, Version=3.0.30930.28736, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

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  • How LINQ to Object statements work

    - by rajbk
    This post goes into detail as to now LINQ statements work when querying a collection of objects. This topic assumes you have an understanding of how generics, delegates, implicitly typed variables, lambda expressions, object/collection initializers, extension methods and the yield statement work. I would also recommend you read my previous two posts: Using Delegates in C# Part 1 Using Delegates in C# Part 2 We will start by writing some methods to filter a collection of data. Assume we have an Employee class like so: 1: public class Employee { 2: public int ID { get; set;} 3: public string FirstName { get; set;} 4: public string LastName {get; set;} 5: public string Country { get; set; } 6: } and a collection of employees like so: 1: var employees = new List<Employee> { 2: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 3: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 4: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 5: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" }, 6: }; Filtering We wish to  find all employees that have an even ID. We could start off by writing a method that takes in a list of employees and returns a filtered list of employees with an even ID. 1: static List<Employee> GetEmployeesWithEvenID(List<Employee> employees) { 2: var filteredEmployees = new List<Employee>(); 3: foreach (Employee emp in employees) { 4: if (emp.ID % 2 == 0) { 5: filteredEmployees.Add(emp); 6: } 7: } 8: return filteredEmployees; 9: } The method can be rewritten to return an IEnumerable<Employee> using the yield return keyword. 1: static IEnumerable<Employee> GetEmployeesWithEvenID(IEnumerable<Employee> employees) { 2: foreach (Employee emp in employees) { 3: if (emp.ID % 2 == 0) { 4: yield return emp; 5: } 6: } 7: } We put these together in a console application. 1: using System; 2: using System.Collections.Generic; 3: //No System.Linq 4:  5: public class Program 6: { 7: [STAThread] 8: static void Main(string[] args) 9: { 10: var employees = new List<Employee> { 11: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 12: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 13: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 14: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" }, 15: }; 16: var filteredEmployees = GetEmployeesWithEvenID(employees); 17:  18: foreach (Employee emp in filteredEmployees) { 19: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 20: emp.ID, emp.FirstName, emp.LastName, emp.Country); 21: } 22:  23: Console.ReadLine(); 24: } 25: 26: static IEnumerable<Employee> GetEmployeesWithEvenID(IEnumerable<Employee> employees) { 27: foreach (Employee emp in employees) { 28: if (emp.ID % 2 == 0) { 29: yield return emp; 30: } 31: } 32: } 33: } 34:  35: public class Employee { 36: public int ID { get; set;} 37: public string FirstName { get; set;} 38: public string LastName {get; set;} 39: public string Country { get; set; } 40: } Output: ID 2 First_Name Jim Last_Name Ashlock Country UK ID 4 First_Name Jill Last_Name Anderson Country AUS Our filtering method is too specific. Let us change it so that it is capable of doing different types of filtering and lets give our method the name Where ;-) We will add another parameter to our Where method. This additional parameter will be a delegate with the following declaration. public delegate bool Filter(Employee emp); The idea is that the delegate parameter in our Where method will point to a method that contains the logic to do our filtering thereby freeing our Where method from any dependency. The method is shown below: 1: static IEnumerable<Employee> Where(IEnumerable<Employee> employees, Filter filter) { 2: foreach (Employee emp in employees) { 3: if (filter(emp)) { 4: yield return emp; 5: } 6: } 7: } Making the change to our app, we create a new instance of the Filter delegate on line 14 with a target set to the method EmployeeHasEvenId. Running the code will produce the same output. 1: public delegate bool Filter(Employee emp); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: var employees = new List<Employee> { 9: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 10: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 11: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 12: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 13: }; 14: var filterDelegate = new Filter(EmployeeHasEvenId); 15: var filteredEmployees = Where(employees, filterDelegate); 16:  17: foreach (Employee emp in filteredEmployees) { 18: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 19: emp.ID, emp.FirstName, emp.LastName, emp.Country); 20: } 21: Console.ReadLine(); 22: } 23: 24: static bool EmployeeHasEvenId(Employee emp) { 25: return emp.ID % 2 == 0; 26: } 27: 28: static IEnumerable<Employee> Where(IEnumerable<Employee> employees, Filter filter) { 29: foreach (Employee emp in employees) { 30: if (filter(emp)) { 31: yield return emp; 32: } 33: } 34: } 35: } 36:  37: public class Employee { 38: public int ID { get; set;} 39: public string FirstName { get; set;} 40: public string LastName {get; set;} 41: public string Country { get; set; } 42: } Lets use lambda expressions to inline the contents of the EmployeeHasEvenId method in place of the method. The next code snippet shows this change (see line 15).  For brevity, the Employee class declaration has been skipped. 1: public delegate bool Filter(Employee emp); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: var employees = new List<Employee> { 9: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 10: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 11: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 12: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 13: }; 14: var filterDelegate = new Filter(EmployeeHasEvenId); 15: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 16:  17: foreach (Employee emp in filteredEmployees) { 18: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 19: emp.ID, emp.FirstName, emp.LastName, emp.Country); 20: } 21: Console.ReadLine(); 22: } 23: 24: static bool EmployeeHasEvenId(Employee emp) { 25: return emp.ID % 2 == 0; 26: } 27: 28: static IEnumerable<Employee> Where(IEnumerable<Employee> employees, Filter filter) { 29: foreach (Employee emp in employees) { 30: if (filter(emp)) { 31: yield return emp; 32: } 33: } 34: } 35: } 36:  The output displays the same two employees.  Our Where method is too restricted since it works with a collection of Employees only. Lets change it so that it works with any IEnumerable<T>. In addition, you may recall from my previous post,  that .NET 3.5 comes with a lot of predefined delegates including public delegate TResult Func<T, TResult>(T arg); We will get rid of our Filter delegate and use the one above instead. We apply these two changes to our code. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: var employees = new List<Employee> { 7: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 8: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 9: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 10: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 11: }; 12:  13: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 14:  15: foreach (Employee emp in filteredEmployees) { 16: Console.WriteLine("ID {0} First_Name {1} Last_Name {2} Country {3}", 17: emp.ID, emp.FirstName, emp.LastName, emp.Country); 18: } 19: Console.ReadLine(); 20: } 21: 22: static IEnumerable<T> Where<T>(IEnumerable<T> source, Func<T, bool> filter) { 23: foreach (var x in source) { 24: if (filter(x)) { 25: yield return x; 26: } 27: } 28: } 29: } We have successfully implemented a way to filter any IEnumerable<T> based on a  filter criteria. Projection Now lets enumerate on the items in the IEnumerable<Employee> we got from the Where method and copy them into a new IEnumerable<EmployeeFormatted>. The EmployeeFormatted class will only have a FullName and ID property. 1: public class EmployeeFormatted { 2: public int ID { get; set; } 3: public string FullName {get; set;} 4: } We could “project” our existing IEnumerable<Employee> into a new collection of IEnumerable<EmployeeFormatted> with the help of a new method. We will call this method Select ;-) 1: static IEnumerable<EmployeeFormatted> Select(IEnumerable<Employee> employees) { 2: foreach (var emp in employees) { 3: yield return new EmployeeFormatted { 4: ID = emp.ID, 5: FullName = emp.LastName + ", " + emp.FirstName 6: }; 7: } 8: } The changes are applied to our app. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: var employees = new List<Employee> { 7: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 8: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 9: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 10: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 11: }; 12:  13: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 14: var formattedEmployees = Select(filteredEmployees); 15:  16: foreach (EmployeeFormatted emp in formattedEmployees) { 17: Console.WriteLine("ID {0} Full_Name {1}", 18: emp.ID, emp.FullName); 19: } 20: Console.ReadLine(); 21: } 22:  23: static IEnumerable<T> Where<T>(IEnumerable<T> source, Func<T, bool> filter) { 24: foreach (var x in source) { 25: if (filter(x)) { 26: yield return x; 27: } 28: } 29: } 30: 31: static IEnumerable<EmployeeFormatted> Select(IEnumerable<Employee> employees) { 32: foreach (var emp in employees) { 33: yield return new EmployeeFormatted { 34: ID = emp.ID, 35: FullName = emp.LastName + ", " + emp.FirstName 36: }; 37: } 38: } 39: } 40:  41: public class Employee { 42: public int ID { get; set;} 43: public string FirstName { get; set;} 44: public string LastName {get; set;} 45: public string Country { get; set; } 46: } 47:  48: public class EmployeeFormatted { 49: public int ID { get; set; } 50: public string FullName {get; set;} 51: } Output: ID 2 Full_Name Ashlock, Jim ID 4 Full_Name Anderson, Jill We have successfully selected employees who have an even ID and then shaped our data with the help of the Select method so that the final result is an IEnumerable<EmployeeFormatted>.  Lets make our Select method more generic so that the user is given the freedom to shape what the output would look like. We can do this, like before, with lambda expressions. Our Select method is changed to accept a delegate as shown below. TSource will be the type of data that comes in and TResult will be the type the user chooses (shape of data) as returned from the selector delegate. 1:  2: static IEnumerable<TResult> Select<TSource, TResult>(IEnumerable<TSource> source, Func<TSource, TResult> selector) { 3: foreach (var x in source) { 4: yield return selector(x); 5: } 6: } We see the new changes to our app. On line 15, we use lambda expression to specify the shape of the data. In this case the shape will be of type EmployeeFormatted. 1:  2: public class Program 3: { 4: [STAThread] 5: static void Main(string[] args) 6: { 7: var employees = new List<Employee> { 8: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 9: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 10: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 11: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 12: }; 13:  14: var filteredEmployees = Where(employees, emp => emp.ID % 2 == 0); 15: var formattedEmployees = Select(filteredEmployees, (emp) => 16: new EmployeeFormatted { 17: ID = emp.ID, 18: FullName = emp.LastName + ", " + emp.FirstName 19: }); 20:  21: foreach (EmployeeFormatted emp in formattedEmployees) { 22: Console.WriteLine("ID {0} Full_Name {1}", 23: emp.ID, emp.FullName); 24: } 25: Console.ReadLine(); 26: } 27: 28: static IEnumerable<T> Where<T>(IEnumerable<T> source, Func<T, bool> filter) { 29: foreach (var x in source) { 30: if (filter(x)) { 31: yield return x; 32: } 33: } 34: } 35: 36: static IEnumerable<TResult> Select<TSource, TResult>(IEnumerable<TSource> source, Func<TSource, TResult> selector) { 37: foreach (var x in source) { 38: yield return selector(x); 39: } 40: } 41: } The code outputs the same result as before. On line 14 we filter our data and on line 15 we project our data. What if we wanted to be more expressive and concise? We could combine both line 14 and 15 into one line as shown below. Assuming you had to perform several operations like this on our collection, you would end up with some very unreadable code! 1: var formattedEmployees = Select(Where(employees, emp => emp.ID % 2 == 0), (emp) => 2: new EmployeeFormatted { 3: ID = emp.ID, 4: FullName = emp.LastName + ", " + emp.FirstName 5: }); A cleaner way to write this would be to give the appearance that the Select and Where methods were part of the IEnumerable<T>. This is exactly what extension methods give us. Extension methods have to be defined in a static class. Let us make the Select and Where extension methods on IEnumerable<T> 1: public static class MyExtensionMethods { 2: static IEnumerable<T> Where<T>(this IEnumerable<T> source, Func<T, bool> filter) { 3: foreach (var x in source) { 4: if (filter(x)) { 5: yield return x; 6: } 7: } 8: } 9: 10: static IEnumerable<TResult> Select<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector) { 11: foreach (var x in source) { 12: yield return selector(x); 13: } 14: } 15: } The creation of the extension method makes the syntax much cleaner as shown below. We can write as many extension methods as we want and keep on chaining them using this technique. 1: var formattedEmployees = employees 2: .Where(emp => emp.ID % 2 == 0) 3: .Select (emp => new EmployeeFormatted { ID = emp.ID, FullName = emp.LastName + ", " + emp.FirstName }); Making these changes and running our code produces the same result. 1: using System; 2: using System.Collections.Generic; 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: var employees = new List<Employee> { 10: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 11: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 12: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 13: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 14: }; 15:  16: var formattedEmployees = employees 17: .Where(emp => emp.ID % 2 == 0) 18: .Select (emp => 19: new EmployeeFormatted { 20: ID = emp.ID, 21: FullName = emp.LastName + ", " + emp.FirstName 22: } 23: ); 24:  25: foreach (EmployeeFormatted emp in formattedEmployees) { 26: Console.WriteLine("ID {0} Full_Name {1}", 27: emp.ID, emp.FullName); 28: } 29: Console.ReadLine(); 30: } 31: } 32:  33: public static class MyExtensionMethods { 34: static IEnumerable<T> Where<T>(this IEnumerable<T> source, Func<T, bool> filter) { 35: foreach (var x in source) { 36: if (filter(x)) { 37: yield return x; 38: } 39: } 40: } 41: 42: static IEnumerable<TResult> Select<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector) { 43: foreach (var x in source) { 44: yield return selector(x); 45: } 46: } 47: } 48:  49: public class Employee { 50: public int ID { get; set;} 51: public string FirstName { get; set;} 52: public string LastName {get; set;} 53: public string Country { get; set; } 54: } 55:  56: public class EmployeeFormatted { 57: public int ID { get; set; } 58: public string FullName {get; set;} 59: } Let’s change our code to return a collection of anonymous types and get rid of the EmployeeFormatted type. We see that the code produces the same output. 1: using System; 2: using System.Collections.Generic; 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: var employees = new List<Employee> { 10: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 11: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 12: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 13: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 14: }; 15:  16: var formattedEmployees = employees 17: .Where(emp => emp.ID % 2 == 0) 18: .Select (emp => 19: new { 20: ID = emp.ID, 21: FullName = emp.LastName + ", " + emp.FirstName 22: } 23: ); 24:  25: foreach (var emp in formattedEmployees) { 26: Console.WriteLine("ID {0} Full_Name {1}", 27: emp.ID, emp.FullName); 28: } 29: Console.ReadLine(); 30: } 31: } 32:  33: public static class MyExtensionMethods { 34: public static IEnumerable<T> Where<T>(this IEnumerable<T> source, Func<T, bool> filter) { 35: foreach (var x in source) { 36: if (filter(x)) { 37: yield return x; 38: } 39: } 40: } 41: 42: public static IEnumerable<TResult> Select<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector) { 43: foreach (var x in source) { 44: yield return selector(x); 45: } 46: } 47: } 48:  49: public class Employee { 50: public int ID { get; set;} 51: public string FirstName { get; set;} 52: public string LastName {get; set;} 53: public string Country { get; set; } 54: } To be more expressive, C# allows us to write our extension method calls as a query expression. Line 16 can be rewritten a query expression like so: 1: var formattedEmployees = from emp in employees 2: where emp.ID % 2 == 0 3: select new { 4: ID = emp.ID, 5: FullName = emp.LastName + ", " + emp.FirstName 6: }; When the compiler encounters an expression like the above, it simply rewrites it as calls to our extension methods.  So far we have been using our extension methods. The System.Linq namespace contains several extension methods for objects that implement the IEnumerable<T>. You can see a listing of these methods in the Enumerable class in the System.Linq namespace. Let’s get rid of our extension methods (which I purposefully wrote to be of the same signature as the ones in the Enumerable class) and use the ones provided in the Enumerable class. Our final code is shown below: 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; //Added 4:  5: public class Program 6: { 7: [STAThread] 8: static void Main(string[] args) 9: { 10: var employees = new List<Employee> { 11: new Employee { ID = 1, FirstName = "John", LastName = "Wright", Country = "USA" }, 12: new Employee { ID = 2, FirstName = "Jim", LastName = "Ashlock", Country = "UK" }, 13: new Employee { ID = 3, FirstName = "Jane", LastName = "Jackson", Country = "CHE" }, 14: new Employee { ID = 4, FirstName = "Jill", LastName = "Anderson", Country = "AUS" } 15: }; 16:  17: var formattedEmployees = from emp in employees 18: where emp.ID % 2 == 0 19: select new { 20: ID = emp.ID, 21: FullName = emp.LastName + ", " + emp.FirstName 22: }; 23:  24: foreach (var emp in formattedEmployees) { 25: Console.WriteLine("ID {0} Full_Name {1}", 26: emp.ID, emp.FullName); 27: } 28: Console.ReadLine(); 29: } 30: } 31:  32: public class Employee { 33: public int ID { get; set;} 34: public string FirstName { get; set;} 35: public string LastName {get; set;} 36: public string Country { get; set; } 37: } 38:  39: public class EmployeeFormatted { 40: public int ID { get; set; } 41: public string FullName {get; set;} 42: } This post has shown you a basic overview of LINQ to Objects work by showning you how an expression is converted to a sequence of calls to extension methods when working directly with objects. It gets more interesting when working with LINQ to SQL where an expression tree is constructed – an in memory data representation of the expression. The C# compiler compiles these expressions into code that builds an expression tree at runtime. The provider can then traverse the expression tree and generate the appropriate SQL query. You can read more about expression trees in this MSDN article.

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  • Rewind request body stream

    - by Despertar
    I am re-implementing a request logger as Owin Middleware which logs the request url and body of all incoming requests. I am able to read the body, but if I do the body parameter in my controller is null. I'm guessing it's null because the stream position is at the end so there is nothing left to read when it tries to deserialize the body. I had a similar issue in a previous version of Web API but was able to set the Stream position back to 0. This particular stream throws a This stream does not support seek operations exception. In the most recent version of Web API 2.0 I could call Request.HttpContent.ReadAsStringAsync()inside my request logger, and the body would still arrive to the controller in tact. How can I rewind the stream after reading it? or How can I read the request body without consuming it? public class RequestLoggerMiddleware : OwinMiddleware { public RequestLoggerMiddleware(OwinMiddleware next) : base(next) { } public override Task Invoke(IOwinContext context) { return Task.Run(() => { string body = new StreamReader(context.Request.Body).ReadToEnd(); // log body context.Request.Body.Position = 0; // cannot set stream position back to 0 Console.WriteLine(context.Request.Body.CanSeek); // prints false this.Next.Invoke(context); }); } } public class SampleController : ApiController { public void Post(ModelClass body) { // body is now null if the middleware reads it } }

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