Search Results

Search found 19802 results on 793 pages for 'linq entity framework'.

Page 15/793 | < Previous Page | 11 12 13 14 15 16 17 18 19 20 21 22  | Next Page >

  • Use LINQ and C# to make a new List from an old List

    - by Addie
    This should be pretty simple, but I am new at LINQ. I have a List of FillList structs. I'd like to use LINQ to create a new List where instead of having the number of buys and sells, I would have one variable containing the sum. For example, if the FillStruct structure has buy = 4 and sell = 2 then the NewFillStruct structure will have numlong = 2. If the FillStruct structure has buy = 2 and sell = 4 then the NewFillStruct structure will have numlong = -2. Here are the structures. struct FillStruct { int buy; int sell; string date; } struct NewFillStruct { int numlong; string date; }

    Read the article

  • username and password check linq query in c#

    - by b0x0rz
    this linq query var users = from u in context.Users where u.UserEMailAdresses.Any(e1 => e1.EMailAddress == userEMail) && u.UserPasswords.Any(e2 => e2.PasswordSaltedHash == passwordSaltedHash) select u; return users.Count(); returns: 1 even when there is nothing in password table. how come? what i am trying to do is get the values of email and passwordHash from two separate tables (UserEMailAddresses and UserPasswords) linked via foreign keys to the third table (Users). it should be simple - checking if email and password mach from form to database. but it is not working for me. i get 1 (for count) even when there are NO entries in the UserPasswords table. is the linq query above completely wrong, or...?

    Read the article

  • Building 'flat' rather than 'tree' LINQ expressions

    - by Ian Gregory
    I'm using some code (available here on MSDN) to dynamically build LINQ expressions containing multiple OR 'clauses'. The relevant code is var equals = values.Select(value => (Expression)Expression.Equal(valueSelector.Body, Expression.Constant(value, typeof(TValue)))); var body = equals.Aggregate<Expression>((accumulate, equal) => Expression.Or(accumulate, equal)); This generates a LINQ expression that looks something like this: (((((ID = 5) OR (ID = 4)) OR (ID = 3)) OR (ID = 2)) OR (ID = 1)) I'm hitting the recursion limit (100) when using this expression, so I'd like to generate an expression that looks like this: (ID = 5) OR (ID = 4) OR (ID = 3) OR (ID = 2) OR (ID = 1) How would I modify the expression building code to do this?

    Read the article

  • How to order the items in a nested LINQ-provided collection

    - by Carson McComas
    I've got a (SQL Server) database table called Category. And another database table called SubCategory. SubCategory has a foreign key relationship to Category. Because of this, thanks to LINQ, each Cateogory has a property called SubCategories and LINQ is nice enough to return all the SubCategories associated with my Category when I grab it. If I want to sort the Categories alphabetically, I can just do: return db.Categories.OrderBy(c => c.Name); However, I have no idea how to order the SubCategories collection inside each Category. My goal is to return a collection of Categories, where all of the SubCategory collections inside of them are ordered alphabetically by Name.

    Read the article

  • Convert SQL to LINQ to SQL

    - by Adam
    Hi I have the SQL query with c as ( select categoryId,parentId, name,0 as [level] from task_Category b where b.parentId is null union all select b.categoryId,b.parentId,b.name,[level] + 1 from task_Category b join c on b.parentId = c.categoryId) select name,[level],categoryId,parentId as item from c and I want to convert it to LINQ to SQL, yet my LINQ skills are not there yet. Could someone please help me convert this. It's the with and union statements that are making this a bit more complex for me. Any help appreciated.

    Read the article

  • LINQ Equivalent query

    - by GilliVilla
    I have a List<string> List<string> students; students.Add("123Rob"); students.Add("234Schulz"); and a Dictionary<string,string> Dictionary<string, string> courses = new Dictionary<string, string>(); courses .Add("Rob", "Chemistry"); courses .Add("Bob", "Math"); courses .Add("Holly", "Physics"); courses .Add("Schulz", "Botany"); My objective now is to get a List with the values - {Chemistry,Botany} . In other words, I am trying to get the LINQ equivalent of select value from [courses] where [courses].key in ( select [courses].key from courses,students where [students].id LIKE '%courses.key%' ) How should the LINQ query be framed?

    Read the article

  • Using condionals in Linq Programatically

    - by Mike B
    I was just reading a recent question on using conditionals in Linq and it reminded me of an issue I have not been able to resolve. When building Linq to SQL queries programatically how can this be done when the number of conditionals is not known until runtime? For instance in the code below the first clause creates an IQueryable that, if executed, would select all the tasks (called issues) in the database, the 2nd clause will refine that to just issues assigned to one department if one has been selected in a combobox (Which has it's selected item bound to the departmentToShow property). How could I do this using the selectedItems collection instead? IQueryable<Issue> issuesQuery; // Will select all tasks issuesQuery = from i in db.Issues orderby i.IssDueDate, i.IssUrgency select i; // Filters out all other Departments if one is selected if (departmentToShow != "All") { issuesQuery = from i in issuesQuery where i.IssDepartment == departmentToShow select i; }

    Read the article

  • Help with Linq and Generics

    - by Jonathan
    Hi to all. I'm triying to make a function that add a 'where' clause to a query based in a property and a value. This is a very simplefied version of my function. Private Function simplified(ByVal query As IQueryable(Of T), ByVal PValue As Long, ByVal p As PropertyInfo) As ObjectQuery(Of T) query = query.Where(Function(c) DirectCast(p.GetValue(c, Nothing), Long) = PValue) Dim t = query.ToList 'this line is only for testing, and here is the error raise Return query End Function The error message is: LINQ to Entities does not recognize the method 'System.Object CompareObjectEqual(System.Object, System.Object, Boolean)' method, and this method cannot be translated into a store expression. Looks like a can't use GetValue inside a linq query. Can I achieve this in other way? Post your answer in C#/VB. Chose the one that make you feel more confortable. Thanks

    Read the article

  • Translating this query in LINQ ? (list of like)

    - by Erick
    I would like to translate this query in LINQ ... it is very easy to construct if we do it in pure SQL but in dynamically created LINQ query (building a search query based on user input) it's a whole new story. SELECT * FROM MyTable WHERE 1=1 AND Column2 IN (1,2,3) AND ( Column1 LIKE '%a%' OR Column1 LIKE '%b%' ) Now to try to construct this we tried it this way : if(myOjb.Column2Collection != null) query = query.where(f => f.Column2.Contains(myOjb.Column2Collection)); if(myObj.Column1Collection != null) { // tough part here ? //query = query.Where(); ... } So what would be the best aproach to this normally ? Note that I am aware of the SqlMethod.Like, tho I can't figure a way to implement it here ...

    Read the article

  • Linq Query - Average Time (DateTime data types)

    - by Jade
    I have a database that has the following records in a DateTime field: 2012-04-13 08:31:00.000 2012-04-12 07:53:00.000 2012-04-11 07:59:00.000 2012-04-10 08:16:00.000 2012-04-09 15:11:00.000 2012-04-08 08:28:00.000 2012-04-06 08:26:00.000 I want to run a linq to sql query to get the average time from the records above. I tried the following: (From o In MYDATA Select o.SleepTo).Average() Since "SleepTo" is a datetime field I get an error on Average(). If I was trying to get the average of say an integer, the above linq query works. What do I need to do to get it to work for datetimes?

    Read the article

  • stepping into a linq query

    - by MyNameIsJob
    Is it possible to step into a linq query? I have a linq to entity framework 4 query in it's simplest form: List = List.Where(f => f.Value.ToString().ToLowerInvariant().Contains(filter.ToLowerInvariant())); It's a query against an Entity Framework DbContext and I'm having trouble seeing why it works for something like: List searching for 001 yields no results against the following list Test001 Test002 Test003 Test004 However any other search yields results (Such as t00 or Test) I was hoping to figure out a way to see the resulting sql but it appears that I need Intellitrace, which I don't currently have or possibly stepping through the query itself and see each iteration build itself.

    Read the article

  • Deferred vs Immediate execution in Linq

    - by Jalpesh P. Vadgama
    In this post, We are going to learn about Deferred vs Immediate execution in Linq.  There an interesting variations how Linq operators executes and in this post we are going to learn both Deferred execution and immediate execution. What is Deferred Execution? In the Deferred execution query will be executed and evaluated at the time of query variables usage. Let’s take an example to understand Deferred Execution better. Example: Following is a code for that. using System; using System.Collections.Generic; using System.Linq; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { var customers = new List<Customer>( new[] { new Customer{FirstName = "Jalpesh",LastName = "Vadgama"}, new Customer{FirstName = "Vishal",LastName = "Vadgama"}, new Customer{FirstName = "Tushar",LastName = "Maru"} } ); var newCustomers = customers.Where(c => c.LastName == "Vadgama"); customers.Add(new Customer {FirstName = "Teerth", LastName = "Vadgama"}); foreach (var c in newCustomers) { Console.WriteLine(c.FirstName); } } public class Customer { public string FirstName { get; set; } public string LastName { get; set; } } } } More on my personal blog @www.dotnetjalps.com

    Read the article

  • LINQ: Enhancing Distinct With The PredicateEqualityComparer

    - by Paulo Morgado
    Today I was writing a LINQ query and I needed to select distinct values based on a comparison criteria. Fortunately, LINQ’s Distinct method allows an equality comparer to be supplied, but, unfortunately, sometimes, this means having to write custom equality comparer. Because I was going to need more than one equality comparer for this set of tools I was building, I decided to build a generic equality comparer that would just take a custom predicate. Something like this: public class PredicateEqualityComparer<T> : EqualityComparer<T> { private Func<T, T, bool> predicate; public PredicateEqualityComparer(Func<T, T, bool> predicate) : base() { this.predicate = predicate; } public override bool Equals(T x, T y) { if (x != null) { return ((y != null) && this.predicate(x, y)); } if (y != null) { return false; } return true; } public override int GetHashCode(T obj) { if (obj == null) { return 0; } return obj.GetHashCode(); } } Now I can write code like this: .Distinct(new PredicateEqualityComparer<Item>((x, y) => x.Field == y.Field)) But I felt that I’d lost all conciseness and expressiveness of LINQ and it doesn’t support anonymous types. So I came up with another Distinct extension method: public static IEnumerable<TSource> Distinct<TSource>(this IEnumerable<TSource> source, Func<TSource, TSource, bool> predicate) { return source.Distinct(new PredicateEqualityComparer<TSource>(predicate)); } And the query is now written like this: .Distinct((x, y) => x.Field == y.Field) Looks a lot better, doesn’t it?

    Read the article

  • Distinct operator in Linq

    - by Jalpesh P. Vadgama
    Linq operator provides great flexibility and easy way of coding. Let’s again take one more example of distinct operator. As name suggest it will find the distinct elements from IEnumerable. Let’s take an example of array in console application and then we will again print array to see is it working or not. Below is the code for that. In this application I have integer array which contains duplicate elements and then I will apply distinct operator to this and then I will print again result of distinct operators to actually see whether its working or not. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Experiment { class Program { static void Main(string[] args) { int[] intArray = { 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5 }; var uniqueIntegers = intArray.Distinct(); foreach (var uInteger in uniqueIntegers) { Console.WriteLine(uInteger); } Console.ReadKey(); } } } Below is output as expected.. That’s cool..Stay tuned for more.. Happy programming. Technorati Tags: Linq,Distinct

    Read the article

  • Is LINQ to objects a collection of combinators?

    - by Jimmy Hoffa
    I was just trying to explain the usefulness of combinators to a colleague and I told him LINQ to objects are like combinators as they exhibit the same value, the ability to combine small pieces to create a single large piece. Though I don't know that I can call LINQ to objects combinators. I've seen 2 levels of definition for combinator that I generalize as such: A combinator is a function which only uses things passed to it A combinator is a function which only uses things passed to it and other standard atomic functions but not state The first is very rigid and can be seen in the combinatory calculus systems and in haskell things like $ and . and various similar functions meet this rule. The second is less rigid and would allow something like sum as it uses the + function which was not passed in but is standard and not stateful. Though the LINQ extensions in C# use state in their iteration models, so I feel I can't say they're combinators. Can someone who understands the definition of a combinator more thoroughly and with more experience in these realms give a distinct ruling on this? Are my definitions of 'combinator' wrong to begin with?

    Read the article

  • Simplify Your Code with LINQ

    - by dwahlin
    I’m a big fan of LINQ and use it wherever I can to minimize code and make applications easier to maintain overall. I was going through a code file today refactoring it based on suggestions provided by Resharper and came across the following method: private List<string> FilterTokens(List<string> tokens) { var cleanedTokens = new List<string>(); for (int i = 0; i < tokens.Count; i++) { string token = tokens[i]; if (token != null) { cleanedTokens.Add(token); } } return cleanedTokens; }   In looking through the code I didn’t see anything wrong but Resharper was suggesting that I convert it to a LINQ expression: In thinking about it more the suggestion made complete sense because I simply wanted to add all non-null token values into a List<string> anyway. After following through with the Resharper suggestion the code changed to the following. Much, much cleaner and yet another example of why LINQ (and Resharper) rules: private List<string> FilterTokens(IEnumerable<string> tokens) { return tokens.Where(token => token != null).ToList(); }

    Read the article

  • How to implement EntityDataSource Where IN entity sql clause

    - by TonyS
    I want to pass a number of values into a parameter of the EntityDataSource, e.g.: Where="it.ORDER_ID IN {@OrderIdList}" (this is a property on the EntityDataSource) <WhereParameters> <asp:ControlParameter Name="OrderIdList" Type="Int16" ControlID="OrderFilterControl" PropertyName="OrderIdList" /> </WhereParameters> This doesn't work as ORDER_ID is of type int32 and I need to pass in multiple values, e.g. {1,2,3} etc The next thing I tried was setting the Where clause in code-behind and this all works except I can't get data binding on DropDownLists to work. By this I mean no value is returned from the bound dropdownlists in the EntityDataSource Updating Event. My ideal solution would be to use a WhereParameter on the EntityDataSource but any help is appreciated. Thanks, Tony. A complete code example follows using the AdventureWorks db: Public Class EntityDataSourceWhereInClause Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load CustomersEntityDataSource.Where = WhereClause ''# reset after each postback as its lost otherwise End Sub Private Sub cmdFilterCustomers_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdFilterCustomers.Click Dim CustomerIdList As New Generic.List(Of Int32) For Each item As ListItem In CustomerIdCheckBoxList.Items If item.Selected Then CustomerIdList.Add(item.Value) End If Next Dim CustomerCsvList As String = String.Join(", ", CustomerIdList.Select(Function(o) o.ToString()).ToArray()) WhereClause = "it.CustomerID IN {" & CustomerCsvList & "}" CustomersEntityDataSource.Where = WhereClause FormView1.PageIndex = 0 End Sub ''# save between postbacks the custom Where IN clause Public Property WhereClause() As String Get Return ViewState("WhereClause") End Get Set(ByVal value As String) ViewState.Add("WhereClause", value) End Set End Property Private Sub CustomersEntityDataSource_Updating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.EntityDataSourceChangingEventArgs) Handles CustomersEntityDataSource.Updating Dim c = CType(e.Entity, EntityFrameworkTest.Customer) If c.Title.Length = 0 Then Response.Write("Title is empty string, so will save like this!") End If End Sub End Class <%@ Page Language="vb" AutoEventWireup="false" CodeBehind="EntityDataSourceWhereInClause.aspx.vb" Inherits="EntityFrameworkTest.EntityDataSourceWhereInClause" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <%''# filter control %> <div> <asp:EntityDataSource ID="CustomerIdListEntityDataSource" runat="server" ConnectionString="name=AdventureWorksLT2008Entities" DefaultContainerName="AdventureWorksLT2008Entities" EnableFlattening="False" EntitySetName="Customers" Select="it.[CustomerID]" OrderBy="it.[CustomerID]"> </asp:EntityDataSource> <asp:CheckBoxList ID="CustomerIdCheckBoxList" runat="server" DataSourceID="CustomerIdListEntityDataSource" DataTextField="CustomerID" DataValueField="CustomerID" RepeatDirection="Horizontal"> </asp:CheckBoxList> <asp:Button ID="cmdFilterCustomers" runat="server" Text="Apply Filter" /> </div> <% ''# you get this error passing in CSV in the where clause ''# The element type 'Edm.Int32' and the CollectionType 'Transient.collection[Edm.String(Nullable=True,DefaultValue=,MaxLength=,Unicode=,FixedLength=)]' are not compatible. The IN expression only supports entity, primitive, and reference types. Near WHERE predicate, line 6, column 15. ''# so have coded it manually in code-behind Where="it.CustomerID IN {@OrderIdList}" %> <asp:EntityDataSource ID="CustomersEntityDataSource" runat="server" ConnectionString="name=AdventureWorksLT2008Entities" DefaultContainerName="AdventureWorksLT2008Entities" EnableFlattening="False" EnableUpdate="True" EntitySetName="Customers" AutoGenerateOrderByClause="false"> </asp:EntityDataSource> <%''# updating works with DropDownLists until the Where clause is set in code %> <asp:FormView ID="FormView1" runat="server" AllowPaging="True" CellPadding="4" DataKeyNames="CustomerID" DataSourceID="CustomersEntityDataSource" ForeColor="#333333"> <EditItemTemplate> CustomerID: <asp:Label ID="CustomerIDLabel1" runat="server" Text='<%# Eval("CustomerID") %>' /> <br /> NameStyle: <asp:CheckBox ID="NameStyleCheckBox" runat="server" Checked='<%# Bind("NameStyle") %>' /> <br /> Title: <%''# the SelectedValue is not Bound to the EF object if the Where clause is updated in code-behind %> <asp:DropDownList ID="ddlTitleBound" runat="server" DataSourceID="TitleEntityDataSource" DataTextField="Title" DataValueField="Title" AutoPostBack="false" AppendDataBoundItems="true" SelectedValue='<%# Bind("Title") %>'> </asp:DropDownList> <asp:EntityDataSource ID="TitleEntityDataSource" runat="server" ConnectionString="name=AdventureWorksLT2008Entities" DefaultContainerName="AdventureWorksLT2008Entities" EnableFlattening="False" EntitySetName="Customers" Select="it.[Title]" GroupBy="it.[Title]" ViewStateMode="Enabled"> </asp:EntityDataSource> <br /> FirstName: <asp:TextBox ID="FirstNameTextBox" runat="server" Text='<%# Bind("FirstName") %>' /> <br /> MiddleName: <asp:TextBox ID="MiddleNameTextBox" runat="server" Text='<%# Bind("MiddleName") %>' /> <br /> LastName: <asp:TextBox ID="LastNameTextBox" runat="server" Text='<%# Bind("LastName") %>' /> <br /> Suffix: <asp:TextBox ID="SuffixTextBox" runat="server" Text='<%# Bind("Suffix") %>' /> <br /> CompanyName: <asp:TextBox ID="CompanyNameTextBox" runat="server" Text='<%# Bind("CompanyName") %>' /> <br /> SalesPerson: <asp:TextBox ID="SalesPersonTextBox" runat="server" Text='<%# Bind("SalesPerson") %>' /> <br /> EmailAddress: <asp:TextBox ID="EmailAddressTextBox" runat="server" Text='<%# Bind("EmailAddress") %>' /> <br /> Phone: <asp:TextBox ID="PhoneTextBox" runat="server" Text='<%# Bind("Phone") %>' /> <br /> PasswordHash: <asp:TextBox ID="PasswordHashTextBox" runat="server" Text='<%# Bind("PasswordHash") %>' /> <br /> PasswordSalt: <asp:TextBox ID="PasswordSaltTextBox" runat="server" Text='<%# Bind("PasswordSalt") %>' /> <br /> rowguid: <asp:TextBox ID="rowguidTextBox" runat="server" Text='<%# Bind("rowguid") %>' /> <br /> ModifiedDate: <asp:TextBox ID="ModifiedDateTextBox" runat="server" Text='<%# Bind("ModifiedDate") %>' /> <br /> <asp:LinkButton ID="UpdateButton" runat="server" CausesValidation="True" CommandName="Update" Text="Update" /> &nbsp;<asp:LinkButton ID="UpdateCancelButton" runat="server" CausesValidation="False" CommandName="Cancel" Text="Cancel" /> </EditItemTemplate> <EditRowStyle BackColor="#999999" /> <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /> <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /> <ItemTemplate> CustomerID: <asp:Label ID="CustomerIDLabel" runat="server" Text='<%# Eval("CustomerID") %>' /> <br /> NameStyle: <asp:CheckBox ID="NameStyleCheckBox" runat="server" Checked='<%# Bind("NameStyle") %>' Enabled="false" /> <br /> Title: <asp:Label ID="TitleLabel" runat="server" Text='<%# Bind("Title") %>' /> <br /> FirstName: <asp:Label ID="FirstNameLabel" runat="server" Text='<%# Bind("FirstName") %>' /> <br /> MiddleName: <asp:Label ID="MiddleNameLabel" runat="server" Text='<%# Bind("MiddleName") %>' /> <br /> LastName: <asp:Label ID="LastNameLabel" runat="server" Text='<%# Bind("LastName") %>' /> <br /> Suffix: <asp:Label ID="SuffixLabel" runat="server" Text='<%# Bind("Suffix") %>' /> <br /> CompanyName: <asp:Label ID="CompanyNameLabel" runat="server" Text='<%# Bind("CompanyName") %>' /> <br /> SalesPerson: <asp:Label ID="SalesPersonLabel" runat="server" Text='<%# Bind("SalesPerson") %>' /> <br /> EmailAddress: <asp:Label ID="EmailAddressLabel" runat="server" Text='<%# Bind("EmailAddress") %>' /> <br /> Phone: <asp:Label ID="PhoneLabel" runat="server" Text='<%# Bind("Phone") %>' /> <br /> PasswordHash: <asp:Label ID="PasswordHashLabel" runat="server" Text='<%# Bind("PasswordHash") %>' /> <br /> PasswordSalt: <asp:Label ID="PasswordSaltLabel" runat="server" Text='<%# Bind("PasswordSalt") %>' /> <br /> rowguid: <asp:Label ID="rowguidLabel" runat="server" Text='<%# Bind("rowguid") %>' /> <br /> ModifiedDate: <asp:Label ID="ModifiedDateLabel" runat="server" Text='<%# Bind("ModifiedDate") %>' /> <br /> <asp:LinkButton ID="EditButton" runat="server" CausesValidation="False" CommandName="Edit" Text="Edit" /> </ItemTemplate> <PagerSettings Position="Top" /> <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" /> <RowStyle BackColor="#F7F6F3" ForeColor="#333333" /> </asp:FormView> </form>

    Read the article

  • Entity Framework 4 and SYSUTCDATETIME ()

    - by GIbboK
    Hi, I use EF4 and C#. I have a Table in my DataBase (MS SQL 2008) with a default value for a column SYSUTCDATETIME (). The Idea is to automatically add Date and Time as soon as a new record is Created. I create my Conceptual Model using EF4, and I have created an ASP.PAGE with a DetailsView Control in INSERT MODE. My problems: When I create a new Record. EF is not able to insert the actual Date and Time value but it inserts instead this value 0001-01-01 00:00:00.00. I suppose the EF is not able to use SYSUTCDATETIME () defined in my DataBase Any idea how to solve it? Thanks Here my SQL script CREATE TABLE dbo.CmsAdvertisers ( AdvertiserId int NOT NULL IDENTITY CONSTRAINT PK_CmsAdvertisers_AdvertiserId PRIMARY KEY, DateCreated dateTime2(2) NOT NULL CONSTRAINT DF_CmsAdvertisers_DateCreated DEFAULT sysutcdatetime (), ReferenceAdvertiser varchar(64) NOT NULL, NoteInternal nvarchar(256) NOT NULL CONSTRAINT DF_CmsAdvertisers_NoteInternal DEFAULT '' ); My Temporary solution: Please guys help me on this e.Values["DateCreated"] = DateTime.UtcNow; More info here: http://msdn.microsoft.com/en-us/library/bb387157.aspx How to use the default Entity Framework and default date values http://msdn.microsoft.com/en-us/library/dd296755.aspx

    Read the article

  • Mapping composite foreign keys in a many-many relationship in Entity Framework

    - by Kirk Broadhurst
    I have a Page table and a View table. There is a many-many relationship between these two via a PageView table. Unfortunately all of these tables need to have composite keys (for business reasons). Page has a primary key of (PageCode, Version), View has a primary key of (ViewCode, Version). PageView obviously enough has PageCode, ViewCode, and Version. The FK to Page is (PageCode, Version) and the FK to View is (ViewCode, Version) Makes sense and works, but when I try to map this in Entity framework I get Error 3021: Problem in mapping fragments...: Each of the following columns in table PageView is mapped to multiple conceptual side properties: PageView.Version is mapped to (PageView_Association.View.Version, PageView_Association.Page.Version) So clearly enough, EF is having a complain about the Version column being a common component of the two foreign keys. Obviously I could create a PageVersion and ViewVersion column in the join table, but that kind of defeats the point of the constraint, i.e. the Page and View must have the same Version value. Has anyone encountered this, and is there anything I can do get around it? Thanks!

    Read the article

  • Entity Framework Duplicate type name within an assembly (6.1.0)

    - by CodeMilian
    I am not sure what is going on but I keep getting the following exception when doing a query. "Duplicate type name within an assembly." I have not been able to find a solution on the web. I had resolved the issue by removing entity framework from all the projects in the solutions and re-installing using nugget. Then all of the sudden the exception is back. I have verified my table schema over and over and find nothing wrong with. This is the query causing the exception. var BaseQuery = from Users in db.Users join UserInstalls in db.UserTenantInstalls on Users.ID equals UserInstalls.UserID join Installs in db.TenantInstalls on UserInstalls.TenantInstallID equals Installs.ID where Users.Username == Username && Users.Password == Password && Installs.Name == Install select Users; var Query = BaseQuery.Include("UserTenantInstalls.TenantInstall"); return Query.FirstOrDefault(); As I mentioned previously the same query was working before. The data has not changed and the code has not changed.

    Read the article

  • Entity Framework - Store parent reference on child relationship (one -> many)

    - by contactmatt
    I have a setup like this: [Table("tablename...")] public class Branch { public Branch() { Users = new List<User>(); } [Key] public int Id { get; set; } public string Name { get; set; } public List<User> Users { get; set; } } [Table("tablename...")] public class User { [Key] public int Id {get; set; } public string Username { get; set; } public string Password { get; set; } [ForeignKey("ParentBranch")] public int? ParentBranchId { get; set; } // Is this possible? public Branch ParentBranch { get; set; } // ??? } Is it possible for the User to know what parent branch it belongs to? The code above is not working. Entity Framework version 5.0 .NET 4.0 c#

    Read the article

  • How to create view model without sorting collections in memory.

    - by Chevex
    I have a view model (below). public class TopicsViewModel { public Topic Topic { get; set; } public Reply LastReply { get; set; } } I want to populate an IQueryable<TopicsViewModel> with values from my IQueryable<Topic> collection and IQueryable<Reply> collection. I do not want to use the attached entity collection (i.e. Topic.Replies) because I only want the last reply for that topic and doing Topic.Replies.Last() loads the entire entity collection in memory and then grabs the last one in the list. I am trying to stay in IQueryable so that the query is executed in the database. I also don't want to foreach through topics and query replyRepository.Replies because looping through IQueryable<Topic> will start the lazy loading. I'd prefer to build one expression and have all the leg work done in the lower layers. I have the following: IQueryable<TopicsViewModel> topicsViewModel = from x in topicRepository.Topics from y in replyRepository.Replies where y.TopicID == x.TopicID orderby y.PostedDate ascending select new TopicsViewModel { Topic = x, LastReply = y }; But this isn't working. Any ideas how I can populate an IQueryable or IEnumerable of TopicsViewModel so that it queries the database and grabs topics and that topic's last reply? I am trying really hard to avoid grabbing all replies related to that topic. I only want to grab the last reply. Thank you for any insight you have to offer.

    Read the article

  • Entity Framework POCO objects

    - by Dan
    I'm struggling with understanding Entity Framework and POCO objects. Here's what I'm trying to achieve. 1) Separate the DAL from the Business Layer by having my business layer use an interface to my DAL. Maybe use Unity to create my context. 2) Use Entity Framework inside my DAL. I have a Domain model with objects that reside in my business layer. I also have a database full of tables that doesn't really represent my domain model. I setup Entity Framework and generated POCO objects by using the ADO.NET POCO Generator extension. This gave me an object for each table in my database. Now I want to be able to say context.GetAll<User>(); and have it return a list of my User objects. The User object is in my business layer. Is that possible? Does that make sense or am I totally off and should start over? I'm guessing I need to use the repository pattern to achieve this, but I'm not sure. Can anyone help?

    Read the article

  • Take,Skip and Reverse Operator in Linq

    - by Jalpesh P. Vadgama
    I have found three more new operators in Linq which is use full in day to day programming stuff. Take,Skip and Reverse. Here are explanation of operators how it works. Take Operator: Take operator will return first N number of element from entities. Skip Operator: Skip operator will skip N number of element from entities and then return remaining elements as a result. Reverse Operator: As name suggest it will reverse order of elements of entities. Here is the examples of operators where i have taken simple string array to demonstrate that. C#, using GeSHi 1.0.8.6 using System; using System.Collections.Generic; using System.Linq; using System.Text;     namespace ConsoleApplication1 {     class Program     {         static void Main(string[] args)         {             string[] a = { "a", "b", "c", "d" };                           Console.WriteLine("Take Example");             var TkResult = a.Take(2);             foreach (string s in TkResult)             {                 Console.WriteLine(s);             }               Console.WriteLine("Skip Example");             var SkResult = a.Skip(2);             foreach (string s in SkResult)             {                 Console.WriteLine(s);             }               Console.WriteLine("Reverse Example");             var RvResult = a.Reverse();             foreach (string s in RvResult)             {                 Console.WriteLine(s);             }                       }     } } Parsed in 0.020 seconds at 44.65 KB/s Here is the output as expected. hope this will help you.. Technorati Tags: Linq,Linq-To-Sql,ASP.NET,C#.NET

    Read the article

  • Need advice on framework design: how to make extending easy

    - by beginner_
    I'm creating a framework/library for a rather specific use-case (data type). It uses diverse spring components, including spring-data. The library has a set of entity classes properly set up and according service and dao layers. The main work or main benefit of the framework lies in the dao and service layer. Developers using the framework should be able to extend my entity classes to add additional fields they require. Therefore I made dao and service layer generic so it can be used by such extended entity classes. I now face an issue in the IO part of the framework. It must be able to import the according "special data type" into the database. In this part I need to create a new entity instance and hence need the actual class used. My current solution is to configure in spring a bean of the actual class used. The problem with this is that an application using the framework could only use 1 implementation of the entity (the original one from me or exactly 1 subclass but not 2 different classes of the same hierarchy. I'm looking for suggestions / desgins for solving this issue. Any ideas?

    Read the article

< Previous Page | 11 12 13 14 15 16 17 18 19 20 21 22  | Next Page >