entity-framework-6

问题 I'm trying something similar to this: How to use scalar-valued function with linq to entity? However I'm not using EDMX, but instead just DbContext and code first. I've come across this: https://codefirstfunctions.codeplex.com/ But the usage isn't suitable. What I am trying to achieve is to be able to do this: var locations = context.Locations.Where(e => Functions.LatLongDistanceCalc(e.Lat, e.Long, lat, long) >= 10) Where it will call a scalar function (LatLongDistanceCalc) on SQL Server. Is

问题 Sql server table: SomeId PK varchar(50) not null OtherId PK int not null How should I map this in EF 6 code first? public class MyTable { [Key] public string SomeId { get; set; } [Key] public int OtherId { get; set; } } I've seen some examples where you have to set the order for each column, is that required? Is there official documentation on this somewhere? 回答1: You definitely need to put in the column order, otherwise how is SQL Server supposed to know which one goes first? Here's what you

问题 Sql server table: SomeId PK varchar(50) not null OtherId PK int not null How should I map this in EF 6 code first? public class MyTable { [Key] public string SomeId { get; set; } [Key] public int OtherId { get; set; } } I've seen some examples where you have to set the order for each column, is that required? Is there official documentation on this somewhere? 回答1: You definitely need to put in the column order, otherwise how is SQL Server supposed to know which one goes first? Here's what you

问题 With EF6 you have a new transaction which can be used like: using (var context = new PostEntityContainer()) { using (var dbcxtransaction = context.Database.BeginTransaction()) { try { PostInformation NewPost = new PostInformation() { PostId = 101, Content = "This is my first Post related to Entity Model", Title = "Transaction in EF 6 beta" }; context.Post_Details.Add(NewPost); context.SaveChanges(); PostAdditionalInformation PostInformation = new PostAdditionalInformation() { PostId = (101),

问题 I used EF 6.2.0 DB first, SQL Server 2017 I created a table to test this create table Person ( ID int primary key, Name varchar(50) ) And I created a form to insert, this is button click event: private void btnSubmit_Click(object sender, RoutedEventArgs e) { Person p = new Person(); p.id = Convert.ToInt32(txbID.Text); p.name = txbName.Text; try { db.People.Add(p); db.SaveChanges(); } catch (Exception ex) { Console.WriteLine("###Ex:" + ex.ToString()); MessageBox.Show(ex.ToString()); } } First,

问题 In my .net solution, I have two different projects: An MVC core web application project and a class library project. In web application project, database connection string is in appsettings.json file. I would like to access that connection string from class library project. Is it possible? If yes, how? If there is any better approach to get connection string, please let me know. 回答1: To make simple and trivial example you could create a class in your class library that will represent

问题 I have a database where all of the dates and times are stored as strings [yyyyMMdd] and [hhmmss] respectively. Is there a data annotation I can add in the POCO class so that it is recognised as the type that it should be? EG: [Column(TypeName="varchar(8)", Format="yyyyMMdd"] // Format does not exist! public DateTime MyDate { get; set; } Or if not, is there a way to define a custom Type and specify how EF should convert the data between the property value and SQL? NOTE: I have no desire to use

问题 I have a generic repository using EF6. The issue has to do with association properties requiring an "Include" even though it shouldn't. The following works: IQueryable<User> dbQuery = _db.Set<User>(); return dbQuery.Where(x => x.Child.Name == "Foo").ToList(); However, the following does not work: Func<User, bool> filter = x => x.Child.Name == "Foo"; IQueryable<User> dbQuery = _db.Set<User>(); return dbQuery.Where(filter).ToList(); It throws an "Object Reference not set..." exception on Child.

问题 My unit of work class is mentioned below and I am using Ninject and I have tried injecting IUnitOfWork per request per thread scope, transient etc. but I am still getting error which is: "Message":"An error has occurred.","ExceptionMessage":"The context cannot be used while the model is being created. This exception may be thrown if the context is used inside the OnModelCreating method or if the same context instance is accessed by multiple threads concurrently. Note that instance members of

问题 I am having a problem deleting some entities due to a foreign key relationship. I understand the following error message and have been doing everything I can think of to delete the entities without incurring this error: The DELETE statement conflicted with the REFERENCE constraint "FK_QuizUserAnswer_QuizWithQuestion". The conflict occurred in database "SomeDatabase", table "dbo.QuizUserAnswer", column 'idQuizQuestion'. The statement has been terminated. Here is an image of the two tables in