Entity Framework Core - Knowledge Base (KB)
6642 results
EF Core Update updates all columns even though only one has changed
I'm kind of new to using EF Core. It was my understanding that EF Core has a "Change Tracker" that looks at the data to see what columns have been modified and builds a SQL UPDATE statement that only updates the modified columns, as described in an answer...
asked by JoeD
EF Core Buffered load of Included entities
I have a query with Include:...dbContext.Set<Person>().Include(x => x.Events) ...There will be 10s of Persons, but 10000s of Events for each Person....I am looking for a generic buffering solution to not use too much memory at any given time....If I use S...
asked by Jakub Fojtik
How can I convert Sql query to Linq and its equivalent with Join() method in Entity Framework Core
select a.* from Article a join ArticleTag at on a.Id = at.ArticleId join Tag t on at.TagId = t.Id where t.Id=8 ...Also I have access to ...IQueryable<Article>..., ...IQueryable<Tag>...and ...IQueryable<ArticleTag>... objects....How ...
asked by Said Roohullah Allem
assign two classes to a generic constraint at runtime
I want to assign two classes to generic constraint at runtime using an OR condition. I don't know if it is possible or not, as I am relatively new to all this....public interface IGenericRepository<TEntity> where TEntity : Employee Department ...I want to...
asked by Nihal Singh
Linq To Entities: String.Contains a list
I am using ...ASP.net Core 3.0... with ...Entity Framework Core 3.0... and ...Pomelo.EntityFrameworkCore... provider for ...MySQL..., I need to query all the users that are from specific Towns. Lets say for example I have a list of strings called ...targe...
asked by Hamza Khanzada
Querying distinct columns across rows filtering by another column
I'm working on a project using Linq and Entity Framework Core. ...I'm struggling with a query. ...I have two data access models....public class JobPost { public int Id {get;set;} public string RoleTitle { get; set;} public Domain Domain1 {get;set;...
asked by arif
EF Core sum on nested collection's properties does not work
My database has the following structure: One User can have many Accounts. One Account can have many Transfers....This is the map configuration. I want to store in my DTO information about each user and his total savings in every account. (the code below r...
asked by Tony Troeff
Recommended way of copying/managing data in my database on startup in .net core/ ef core?
The gist of my situation is that I'm dealing with a big database, and depending on the contents of it my code could do all kinds of unexpected things. The data is large, but it's not expected to change heavily any time soon, it's all in a single database ...
asked by Yori Dj
Why is the code inside the method executed twice?
The code inside the ...CustomerRepository.GetCustomers()... method is executed twice.... Why is this happening?... Â ... In the picture, I showed the steps for executing the code inside the method.... Â ...Description.... The code comes in step "5"....
asked by koverflow
Any way to use method in EF Select extension?
I have method which returns a ViewModel async:... public async Task<CardUserBindingViewModel> GetCardUserBindingViewModel(int cardId) { /// ... creditStatus, remainCreditDays return await Task.Run(() => new CardUserBindingVi...
asked by Mehdi
Oracle DB with .NET Core Using ODP.Net Provider - How to set the Schema
Having trouble getting things to work with an Oracle Database in .NET Core. ...I am able to create a connection to the database.... My problem seems to be when I try to execute a statement. I first was using EF Core with a DbContext to retrieve a single...
asked by BioData41
IsNumeric in EF Core
Is there an equivalent of IsNumeric in EF Core or by using linq or Dynamic Sql or similar? ...I am trying to get only the rows with numeric values from a nvarchar column.
asked by Fred
Setting a column unique null without being an index in .NET EF Core
I would like to add a field to a table that should be unique, but is not required (so it can be null) and it is not an index. This is doable with SQL, something like this in mysql:...CREATE TABLE MyTable ( ... field VARCHAR(255) UNIQUE ... ) ...I tr...
asked by Tiago Mendonça
How do I fill in an ignored field inside OnModelCreating?
I use the same entity in two DbContexts....public class ActualDbContext : DbContext { public DbSet<Doc> Docs { get; set; } } public class ArchivedDbContext : DbContext { public DbSet<Doc> Docs { get; set; } } public class Doc { ... } ...How ...
asked by Michael Zagorski
ASP.NET Core + Entity Framework Core + SQLite Creating initial migration throws error
I am doing a ASP.NET Core beginner tutorial on Udemy. The task is to create a Code First SQLite database and I want to create a Initial migration which is failing. Below I describe the steps I have made....I have installed the packages ...Microsoft.Entity...
asked by canvee
Use array of ints parameter in FromSQL query and Where In clause
I have a list of ints:...var ids = new List { 10, 20 };...And I need to find Users with that ids:...context.Users.FromSqlInterpolated($@" select Users.* where Users.Id in ({String.Join(',', ids)})" ...But I get the following error:...'Conversion fai...
asked by Miguel Moura
I get a an error when the Date is null but cannot understand why and how to fix it
This is driving me crazy:... using (var context = new aContext()) { _Paz = context.TPaz .Where(a => a.CodPaz == _PazV.CodPaz) .FirstOrDefault(); } ...I have 2 different row...
asked by Massimo Savazzi
Duplicate table created when adding IdentityUser as foreign key in ASP.NET Core 3.1
I am using PostgreSql as my DB. I am trying to add a foreign key to the user's table but instead of that a duplicate ...IdentityUser... table is being created....I have inherited ...IdentityDbContext<IdentityUser>... for ...ApplicationDbContext... whose c...
asked by Akshay
EF Core - how to audit trail with value objects
I'm trying to implement an Audit Trail (track what changed, when and by whom) on a selection of classes in Entity Framework Core....My current implementation relies on overriding OnSaveChangesAsync:...public override Task<int> SaveChangesAsync(bool accept...
asked by Simopaa
System.AggregateException in Program.cs in ASP.NET Core MVC
I have an ASP.NET Core MVC application which uses Entity Framework Core O/RM. I am implementing generic repository pattern in my application. There are two entities, ...Employee... & ...Department.... There is one context class ...EmployeeDepartmentDetail...
asked by Nihal Singh
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