Entity Framework 6 - Knowledge Base (KB)
6940 results
Get error when scaffold MS Access database (Could not find installable ISAM)
I am using Entity Framework 6 to manage an MS Access database (mdb file). I am now using this project (bubibubi / EntityFrameworkCore.Jet) But in their example, it uses a * .accdb file while I'm using a * .mdb file. When i execute:...Scaffold-DbContext -C...
asked by Carlos Alberto Armiliato
How to handle duplicate value Exception in Entity Framework?
I have a ...Users... model class which has ...UserID... as primary key. I want to handle the exception if duplicate value for ...UserID... (primary key) is inserted and display a proper message to the user....I tried to handle exception by using ...try {...
asked by Zahid
how DbContext.AttachRange() works in this scenario
I saw a book with some code like this:...public class Order { public int OrderID { get; set; } public ICollection<CartLine> Lines { get; set; } ... } public class CartLine { public int CartLineID { get; set; } public Product Product { get...
asked by slowjams
Cast a nullable DateTime in a lambda expression
Using EF6 I want to get all objects of the year 2019 from my database CALENDRIER, but EF6 generates nullables DateTimes "DateTime?" instead of usual DateTimes. Because I want only the year, I could use the Year field from the DateTime to filter my List, b...
asked by M. Ozn
How to avoid connections against empty/null database by Entity Framework
We use entity framework to read from an existing database. This is a simplified version of our code....using (my context context = new mycontext()) { if(context.Database.Connection.State == System.Data.ConnectionState.Closed) { _logger.Inf...
asked by Vicent Galiana
Entity Framework 6.2 copy many to many from one DbContext to another DbContext
When working with a network database such as MySQL, the DbContext should be short lived, but according to ...https://www.entityframeworktutorial.net/EntityFramework4.3/persistence-in-entity-framework.aspx... the DbContext can be long lived when working wi...
asked by Jinjinov
How can data be streamed from a LINQ to Entities query?
I'm wondering how one would go about streaming data from SQL server using EF6....Assume having these classes...PersonRepository...EFPerson (EF model)...DomainPerson (Domain model)...PersonUsingClass...Assume that PersonUsingClass depends on getting a bunc...
asked by Treeline
EF6 How do I retain a custom sql generator while disabling automatic migrations
We use entity framework 6 in our application, along with a Custom Sql Server Migration Generator that handles some edge cases when generating migrations....We use add-migration to add a new migration to the system, and then when the application is deploye...
asked by dylanT
The argument 'sql' cannot be null, empty or contain only white space. When first create the database
I'm using ...entity framework... to process the ...sqlite... database. If there's no database and I want to insert one record, it will create the database successfully (I found the database file in disk) but throw the error: ...The argument 'sql' cannot b...
asked by Chen Jason
How to get first day of month/year etc?
I'm using ...Linq.Dynamic... to query a ...SQL Server... database....I have a date field named 'EnteredOn' which I need to convert to first second of that month (or year, minute etc)...I tried basically everything, but everything throws an error...Here ar...
asked by Yisroel M. Olewski
Joining two tables using Include() with conditional filter
I have existing code to update. I want to join another table called ...Table3.... Since the query has an ...include... to ...Table2..., I want to add another ....Include... with a conditional filter and avoid a left join....When I add the ....include... w...
asked by c0micrage
Use a variable to call a method
I'm using Entity framework to manipulate a data base, and I was wondering if I could used a variable to call a method...I tried with this way:...string name = "tableName"; db.[name].AddRange(dates.[name]); ...but it didn't work...I want to call a method o...
asked by Johnatan De Leon
Using Entity Framework with Multiple Databases and Providers in the Same Project (SQL Server and MySql)
Background:...I have an application (both web forms and console) that easily accesses multiple SQL Server databases using Entity Framework code first with no problems. I can switch back and forth between contexts with no errors. Now I'm trying to add in a...
asked by Mike
Update Navigation Property in Entity Framework
I am a new at depth of the Entity Framework I have just wondered why Entity Framework doesn't save changes especially the navigation property although all other properties are already updated Please I want simple explanation ...This is My Service Class ...
asked by Peter Tharwat
Is a DbContext per thread in Parallel.ForEach safe?
I am working a contract right now to increase the performance of a back end services for a modern SaaS SPA web app that is using EF 6 as their ORM. The first thing I proposed was to introduce some multi-threading to their back end service which is curren...
asked by Casey Chester
Using nullable for Foreign Key in Entity Framawork
I use EF Code First approach in an ASP.NET MVC project and I have PK-FK relations on several entities as shown below: ...public class Staff { public int Id { get; set; } //Foreign key for Project public int ProjectId { get; set; } public...
asked by hexadecimal
Cascade delete in Entity Framework 6 fails to delete dependents. Any suggestions
I am new to Eternity Framework 6 and I read that by default Cascade Delete is enabled. I currently have the following models...public class Student { public int Id { get; set; } public List<Sport> Sports { get; set; } public string StudentNa...
asked by MistyD
Missing map CreateMap exception for related entity (AutoMapper & code first)
I'm struggling with Automapper conventions. How are you mean't to include the related entities in your dto's from code first? I've gone through many examples from various times in Automappers history but nothing works so far. The one that makes most sense...
asked by brioni
Call stored procedure from EF asynchronously using C# inside async method
We are moving to Entity Framework, however we have a large number of stored procedures. If our Web API uses an async/await pattern all the way to the stored procedure call, how do I handle the call? Can I/should I make it async as well?...I have a db cont...
asked by Robin
Entity Framework stored column mapping issue with DTO
I'm retrieving columns from database using a stored procedure and binding values into my DTO class through EF code first approach....I'm facing issue to get the values for ...ReferenceNumber..., ...BookingNumber... properties. I'm getting empty values for...
asked by user1928165
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