EF Core

Blazor

Azure

cosmos

Bring in empty new navigation class to razor pages page model

31 Jul 2018 by ParsleySage

EF Core 2.1 (using Razor Pages) I have a table, model and Razor Crud Pages to create new Examination schedules. The db table and model has a foreign key ID to an Examination Dates table and model, which in turn contains key dates that require adding/updating to an Exam schedule at various...

Bring in empty new navigation class to razor pages page model

31 Jul 2018 by Mike V Baker

1) This isn't going to be specific to your situation because you're not posting any code so I can't see into your data model. But if you're using EF then you don't have to worry about the primary key foreign key values because that's entity framework's job. Your DBContext will have a data...

Case Insensitive Search Filter in OData ASP.NET Core 2.0 Web API as an OWIN Middleware

31 Jan 2018 by Pawel idzikowski

How to replace the web API request query string to provide case insensitive OData search

Changing primary key data type in EF Core

22 Jun 2017 by Kurt Swendson

How to make the migrations to change data type

.NET

Dev

Choose Your Poison on the rPi: Entity Framework, Linq2DB, or ADO.NET

17 Oct 2019 by Marc Clifton

Performance differences on the rPi

Concurrency Handling In Entity Framework 6 (Database First Approach)

1 May 2017 by Roshan Choudhary

Handling data concurrency in Entity Framework 6 with Database First Approach.

Customize Entity Framework Core Migration History Table

3 Aug 2022 by DiponRoy

Options to customize EF Core migration table

Delete All Rows in Entity Framework Core 6

15 Aug 2022 by DiponRoy

How to delete all rows in EF Core 6 using alternate options

unit-testing

EF core 3.1: include userroles in user

25 Nov 2020 by csrss

Hi. I am trying for a couple of days now and just cannot make it work. It seems like pretty obvious task, however. public class UserRole : IdentityUserRole { public virtual User User { get; set; } public virtual...

EF Core 3.x Support for SQL Server's TRY_PARSE Function

28 Feb 2022 by Richard Deeming

EF Core methods to call SQL Server's TRY_PARSE function

EF core 5 order by dictionary table name/value possible?

31 Aug 2021 by Member 14637786

Hello, is this possible to write SQL-translatable query to order by a dictionary table? For instance: class Customer { string Name {get;set;} IEnumerable CustomProps {get;set;} } class CustomProperty { string Name...

EF core 5 order by dictionary table name/value possible?

31 Aug 2021 by Richard Deeming

Try: .OrderBy(x => x.CustomProps.Where(p => p.Name == "Color").Select(p => p.Value).FirstOrDefault()) Or: .OrderBy(x => x.CustomProps.Where(p => p.Name == "Color").Select(p => p.Value).Min())

EF core 5 split table to two entities

10 Jul 2021 by Manos Kanellopoulos

Im using DDD in my project and I have an entity which belong to two bounded contexts with different properties each one. Both bounded contexts add records by this entity. How can I configure these two classes to map to same table by fluent Api? ...

EF core 5 split table to two entities

10 Jul 2021 by #realJSOP

Try using the mapped entity as a base class for two derived entities.

EF Core ApplyConfigurations Implementation

3 Jun 2018 by saadishahin

A quick psedu-code for EF Core that's equivalent to modelBuilder.Configurations.AddFromAssembly in entity framework

Ef core filtering included query using uow and repository

16 May 2022 by Mahfoud Bouabdallah 2022

I started creating a role-based security system in my WinForm application so I began with Form navigation (Permission Navigation) and this is my entity's public partial class User { public User() { UsersToRoles = new...

Ef core filtering included query using uow and repository

16 May 2022 by Mahfoud Bouabdallah 2022

I decided to go this way: When the user has successfully logged in, I catch the Id then I make a call to get all roles related to that user after that I make another call to get all permission navigation using role Id that I got earlier.

Ef core fromsqlraw: unable to call stored procedure

2 Jun 2021 by csrss

Hi. I am trying to understand this method for a whole day long now now. I need to call a stored procedure, which does not return, or at least does not suppose to return anything. Just like a void method call. However, no matter what I am trying...

Ef core fromsqlraw: unable to call stored procedure

2 Jun 2021 by Gerry Schmitz

Your query has nothing to do with EF; there is no relation between it and any EF entities; it's a simple C# SQL SP call. (If MyClassSet had elements, it might work, but that's only because you made your query dependent on it) sql server - How to...

Ef core fromsqlraw: unable to call stored procedure

2 Jun 2021 by Richard Deeming

If you don't want to return any results, don't use FromSqlRaw on a DbSet; use the ExecuteSql* extension methods on the Database façade. int returnValue = context.Database.ExecuteSqlRaw("EXEC procedure_name;"); ...

EF core usage in multi database application

29 May 2023 by hardover

Basic situation is: Application manages a standard set of records for an organization. It will work on only one organization at a time. App must be able to create a new organization on request. App should be able to create a database for a...

EF core usage in multi database application

29 May 2023 by Graeme_Grant

What you are trying to achieve is multi-tenancy. Here is a google search that will point you in the right direction: ef core multi-tenancy - Google Search[^]. First link returned: Multi-tenancy - EF Core | Microsoft Learn[^]

EF core, handle arrays

14 Nov 2020 by csrss

Hello everyone. This is my Entity, which is stored in database: public class Rule { [Key] public int ruleId { get; set; } public string name { get; set; } public int[] categoryIds { get; set; } } I...

EF core, handle arrays

14 Nov 2020 by Gerry Schmitz

If you need a "string" to act like a "list", just add another Getter; EF / LINQ doesn't care. public string Categories {get;set;} = "1;2;3"; public ICollection CatList {get{return this.Categories.Split(';').ToList();}}

EF-core: delete related entities

3 Dec 2020 by csrss

There are 2 tables: public class Info { [Key] public int id { get; set; } public int name { get; set; } public int surname { get; set; } } public class Client { [Key] public...

Linq2Sql

EF-core: delete related entities

3 Dec 2020 by Richard Deeming

Cascade Delete - EF Core | Microsoft Docs[^] Assuming this is a one-to-one relationship[^]: protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity() .HasOne(c => c.info) .WithOne(i...

Linq2Sql

EF8 – Row SQL returning Non-entities

1 Apr 2024 by Mark Pelf

Overview of new changes to EF8 – support for Row SQL returning Non-entities.

Entity Framework Core 2 for the Enterprise

8 Feb 2020 by HHerzl

Entity Framework Core 2 for the Enterprise

Entity Framework Core Code First Publishing Multiple Db Contexts in the Same Database

7 Aug 2022 by DiponRoy

EF Core first publishing multiple DB contexts in same DB

CodeFirst

Entity Framework: Separate Entity Class Mapping using Fluent API

6 Nov 2018 by MdAsifBd

Separate entity class mapping using Fluent API

Entityfreamework core 2 slow in first query

16 Feb 2019 by Ahmed Dabas

I'm working on an desktop app using (wpf , EF Core) and i note that response little bit slow in first query when application run first time , then every thing ok what is the cause of this problem? and how can i handel it ? What I have tried: i can't solve it , the problem still

Entityfreamework core 2 slow in first query

16 Feb 2019 by Dave Kreskowiak

That is the "warm up time" for EF. It's doing a first connection to the database and verifying that the structure matches what it expects in order to work with your context. There is nothing you can do to "fix" that.

Entityfreamework core 2 slow in first query

16 Feb 2019 by Gerry Schmitz

You run a scheduler that every morning fires off the "first query of the day" while everyone else is sleeping.

Error in relationship between two models have more keys in ASP.NET core 2.1

18 Nov 2018 by ahmed_sa

Problem The relationship from 'SalesFooter.SaleHeaders' to 'SalesHeader.SalesFooters' with foreign key properties {'SalesOrderNo' : int} cannot target the primary key {'SalesOrderNo' : int, 'SalesType' : int, 'SalesYear' : int, 'BranchCode' : int} because it is not compatible. Configure a...

MVC

Error in relationship between two models have more keys in ASP.NET core 2.1

18 Nov 2018 by Sk Imad

If you want to get relation with both class, the property name should not be same in both class.

MVC

Execute Stored Procedure using Entity Framework Core in .NET Core Class Library Project

10 Feb 2017 by PrashantRamteke

Execute stored procedure using Entity Framework Core in .NET Core Class library project

Expression #6 select list is not in group by clause and contains nonaggregated column

26 Feb 2019 by Golden Basim

i created this view to calculate the total stocks of every item in every store as : CREATE OR REPLACE VIEW `view_items_stocks_smallest_unit_prices_noserials` as SELECT items.stitems_ID, items.stitems_Status, items.stitems_Name, items.stitems_Type, ...

EF6.0

MySQL

Expression #6 select list is not in group by clause and contains nonaggregated column

26 Feb 2019 by OriginalGriff

See here: SQL GROUP By and the "Column 'name' is invalid in the select list because..." error[^]

EF6.0

Getting Started with Entity Framework Core: Building an ASP.NET Core Application with Web API and Code First Development

MySQL

Fixes to LINQ to SQL Explicit Client Evaluation which Causes Poor Performance

25 Dec 2021 by scott_liu

Entity Framework Core client evaluation was disabled by default since version 3.0 because of performance.

From MVC to Razor Pages

1 Oct 2017 by Marcelo Ricardo de Oliveira

Building a tiny e-Commerce on ASP.NET Core, Razor pages, React JS.NET and EF Core

5 Dec 2017 by Vincent Maverick Durano

This article demonstrates how to build an ASP.NET Core application using Entity Framework Core Code-First development with Web API and MVC.

Getting Started with Entity Framework Core: Database-First Development

10 Oct 2017 by Vincent Maverick Durano

This article is the first part of the series on Getting Started with Entity Framework Core. In this post, we will build an ASP.NET Core MVC application that performs basic data access using Entity Framework Core.

GraphQL for .NET Developers

21 Jul 2021 by Jeremy Likness

In this blog post I look at what GraphQL is, share benefits and challenges, review the current .NET ecosystem, and walk you through some hands-on examples.

How can I use EF 3.0 in .NET framework ?

31 Oct 2019 by Richard MacCutchan

EF 3.0 in .Net - Google Search[^]

How can I use EF 3.0 in .NET framework ?

1 Nov 2019 by Richard Deeming

As you've discovered, you can't: Breaking changes in EF Core 3.0 - EF Core | Microsoft Docs[^]: Starting with 3.0, EF Core targets .NET Standard 2.1 and will run on all platforms that support this standard. This does not include .NET Framework.

How do I call the stored procedure in entity framework core to retrieve the data

20 Feb 2019 by avelsamy

Hi, i have created the stored procedure which returns data from multiple tables. Here i i am unable(don't know) to call the stored procedure with parameter. Can anyone please help me to resolve this. I tried with one scenario its returns Id = 18, Status = WaitingForActivation, Method =...

C#5.0

How do I call the stored procedure in entity framework core to retrieve the data

20 Feb 2019 by Gerry Schmitz

How to: Execute a Parameterized Stored Procedure Using EntityCommand | Microsoft Docs[^] EntityClient Provider for the Entity Framework | Microsoft Docs[^]

C#5.0

How do I write complex group by LINQ query in dot net core 3.1 ?

16 Jul 2020 by Torakami

The problem is that, in the group by I want the first result in the group by using first() or firstOrDefault() but I get an error saying Quote: could not be translated. Either rewrite the query in a form that can be translated, or switch to...

How do I write complex group by LINQ query in dot net core 3.1 ?

16 Jul 2020 by Richard Deeming

EF Core's GroupBy support can be a bit flaky. Try starting the query with the users instead: var skipperLocations = _appContext.Users .Select(u => u.Locations .Where(l => l.Timestamp > cutOffDate) .OrderByDescending(l =>...

How do we put CAST with format with linq to entities in EF core

7 Apr 2021 by nrramesh

select * from Table where CAST(FORMAT(column,'00.00') as varchar(20)) LIKE '%03.1%' Now, I have a IQueryable and want to send the Query through LINQ with the given format What I have tried: obj.Number.ToString("{0:0.00}")

How do we put CAST with format with linq to entities in EF core

7 Apr 2021 by Richard Deeming

Define the function(s) you want to call: public static class SqlFunctions { public static string Format(decimal? value, string format) => value?.ToString(format) ?? string.Empty; public static void Register(ModelBuilder...

How to configure controller and model's foreign key to accept only wanted field

14 Jun 2022 by Anvarkhon Khamzaev

There are two entities Task and User. Task entity has two foreign keys (both int - id) Performer and Creator that is linked to User entity Id field. They are shadow properties, so in db their name are PerformerId and CreatorId. When I try to test...

How to Easily Map EntityFramework/EntityFrameworkCore Entities from/to DTOs

22 Oct 2023 by David_Cui

To introduce a free library to save some tedious work for writing mapping code between entities and DTOs

JSON

How to ensure the query uses a single context instance?

18 Apr 2023 by xTMx9

Hello, I am currently facing an error when running a method that could be related to 2 connectoin instances running at the same time but I can't find how is it happening exactly. The error: InvalidOperationException: Cannot use multiple context...

.NET6

How to ensure the query uses a single context instance?

18 Apr 2023 by Richard Deeming

Quote: I have checked the program.cs file and all services are registered as "Transient" in it. Well, there's your problem. Services registered as "transient" will have a new instance created every time they are resolved. You have two (or...

.NET6

How to include class position in .NET core

9 Aug 2022 by Difameg Network Nigeria

Hi, I am working on a simple student result. I want to achieve student Positions per class. // I have this two models public class StudentData { [Key] public int Id { get; set; } [Display(Name = "StudentClass")] ...

How to include class position in .NET core

9 Aug 2022 by Richard Deeming

Your ViewResult class represents the data for a single student. Your foreach loop would overwrite the properties of that class with the values for the last student returned. That is, it would do that, if your code compiled. But your code won't...

How to reverse a paged datasource using EF core?

1 Aug 2022 by Code4Ever

I use the following code to get paged data to the DataGerid: using (var _sqliteContext = new SQLiteContext()) { AssociatedObject.LoadDynamicItems(e.StartIndex, await _sqliteContext.Equipments ...

How to reverse a paged datasource using EF core?

29 Jul 2022 by Gerry Schmitz

If you want to display the last page, retrieve the last page: .TakeLast( e.PageSize ); Enumerable.TakeLast(IEnumerable, Int32) Method (System.Linq) | Microsoft Docs[^]

How to reverse a paged datasource using EF core?

1 Aug 2022 by Richard Deeming

You can't "reverse the order" of that data source, because you haven't defined any order for it. The data will be returned in whatever order the SQL engine chooses to load it. Whilst that might appear to be stable at the moment, it can and will...

How to scale up background job( console application) in .NET core with out any concurrency issues?

21 Jan 2021 by Christian Graus

No one can give you a definite answer because your question is vague. What is the task? You need to break the task into atomic parts so different threads can work in isolation

How to store selected id and selected text on hidden field using razor

9 Jul 2023 by Graeme_Grant

Already answered here: How to store data on ASP.NET razor page using hidden field?[^]

How to store selected id and selected text on hidden field using razor

9 Jul 2023 by ahmed_sa

I work on razor asp.net core . I face issue i can't store selected value id and selected text of select option drop down on hidden fields so I need to create two hidden fields first hidden field to store selected value id and second for store...

How to update a record in a many to many relationship

31 Jan 2020 by ElenaRez

I’m implementing a project using asp.net core and I'm new in this field. Employing DB first approach and creating models in Visual studio, in SQl server I have two tables called API and Applicant that have many to many relationship and there is also their junction table called ApiApplicant....

How to update a record in a many to many relationship

31 Jan 2020 by Bertha Wwallace

var dbContext = new MyEntitiesDbContext(); var theApiapplicant = dbContext.Apiapplicants.Where(a => a.Id == myApiapplicantId).FirstOrDefault(); theApiapplicant.IsDeleted = true; dbContext.SaveChanges(); Have fun!

Id could not be removed when attached multiple entities with the same id

8 Jun 2023 by Mahfoud Bouabdallah 2022

I have three class GdsReceptionBlackProduct, Employee and Customer public partial class GdsReceptionBlackProduct { public int Id { get; set; } public string? CreatedBy { get; set; } public virtual Employee?...

Id could not be removed when attached multiple entities with the same id

8 Jun 2023 by Richard Deeming

You have a combination of two settings which are causing this: entity.Navigation(e => e.Country).AutoInclude(); This causes the Country navigation property to always be included in any query that loads a Customer. ...

Implementing Common Audit Fields with EF Core’s Shadow Property

22 Mar 2017 by Fiyaz Hasan

Know how to use Entity Framework's new shadow property feature for easily implementing common audit fields for entities

auditing

Inspect and Mutate IQueryable Expression Trees

21 Aug 2020 by Jeremy Likness

How do products like EF Core allow you to write whatever queries you like, then successfully intercept them to run SQL commands? The secret is in the provider.

Integration Testing of a .NET Core Application with a Database Dependency

10 May 2020 by Daan Acohen

The test problems you face when having a database dependency and how to resolve these problems

Issues with select in LINQ2SQL

16 Nov 2020 by csrss

Hello friends! Here are my entities: public class Subscription { [Key] public int id { get; set; } public string name { get; set; } public double data { get; set; } } public class...

Linq2Sql

LINQ to Entities, Cross Apply, and Left Outer Join

12 May 2017 by DaveDavidson

In this article, I show LINQ to Entities syntax that will produce queries with CROSS APPLY and LEFT OUTER JOIN clauses.

Lists in entity framework core doesnt populate

1 Apr 2017 by Stein The Ruler

Hi! I have two classes; Item and ItemType. Item contains ItemTypeId and ItemType contains a list over Items. But the Items list never gets populated. Its always 0. Item: public class Item { public int Id { get; set; } public string Name { get; set; } public...

Lists in entity framework core doesnt populate

1 Apr 2017 by Stein The Ruler

I must have missed the part about loading entities. I added a GetItemType method to my DbContext which loads the relational data public async Task GetItemType(ItemType.ListTypes type) { ItemType result = await this.ItemTypes.Include(i =>...

Look up the nested parents (self-reference) until condition is met in EF core LINQ?

15 Jul 2020 by Member 14637786

Hello, is there a good and fast way to get a single Parent object (or its id) by condition without iterating up all the levels of self-referencing relationship? The model is for example this (pseudocode): class MyObject { bool myCondition;...

Look up the nested parents (self-reference) until condition is met in EF core LINQ?

14 Jul 2020 by #realJSOP

Create a stored proc and call it from EF to populate the colle ction. Let the query in the stored proc add the necessary "relationship" columns and populate them. At that point, your child objects should have a reference to the parent. Let the...

Look up the nested parents (self-reference) until condition is met in EF core LINQ?

14 Jul 2020 by Laxmidhar tatwa technologies

public class MyBuilding { public int id { get; set; } public List MyFloors { get; set; } } public class MyFloor { public int id { get; set; } public List MyOfficerooms { get; set;...

Look up the nested parents (self-reference) until condition is met in EF core LINQ?

14 Jul 2020 by #realJSOP

Your model makes absolutely no sense. 0) The MyCondition property doesn't appear to have any association with the specified question. 1) The ParentID property should be called ID because it's the id of the object, not the parent object.. ...

Look up the nested parents (self-reference) until condition is met in EF core LINQ?

15 Jul 2020 by Richard Deeming

Are you free to modify the table structure? If so, you might be able to use a HierarchyID column. hierarchyid (Transact-SQL) - SQL Server | Microsoft Docs[^] It's not supported natively, but there's a third-party library which adds support to EF...

Move Entity Framework Core v5.0 to a Separate Project

7 Apr 2021 by mark_worrall

How to move Entity Framework Core v5.0 into a separate Visual Studio Project

Mvc 5 controller with views, using entity framework

9 Apr 2017 by NalaBI

I am trying to create a Controller for MVC5 using Entity Framework. but I keep encountering an error. 'Unable to retrieve metadata'. It also says The argument connectionString cannot be null, empty or contain White Space.What I have tried:I have tried to rebuild. Checked the...

Mvc 5 controller with views, using entity framework

9 Apr 2017 by NalaBI

I found the problem it was with my database tables data types.

NET5: dbcontext: owned entites: how to store class property in same datatable

24 Sep 2021 by Sni.DelWoods

I have a custom DateTime-Range class which is used in several models: public class Entity { //... public DateTimeRange Usage {get; set; } //.... } public class DateTimeRange { public DateTime From { get; set; } public DateTime...

.NET

NET5: dbcontext: owned entites: how to store class property in same datatable

24 Sep 2021 by Sni.DelWoods

Solved. The anontation does the whole job: [Owned] public class DateTimeRange { public DateTime From { get; set; } public DateTime To { get; set; } } Output datatable is as exptected: Validity_From = ... Validity_To = ... ...

.NET

Problem loading related data in entity framework core

23 Apr 2019 by Bohdan Stupak

I'm afraid you can't since Include loads all the data for your navigational property. If you are concerned with the amount of data loaded I would rather suggest you not to load the whole dataset in memory. Instead, apply some filtering to load only data you require. Also, consider learning about...

WebAPI

Problem with EF code first migrateasync method

26 Oct 2018 by Simon_Whale

I have just started on a new project, where the database is built using code first. I have attempted to run the project for the first time and get the below Exception. I have checked that using (var serviceScope = serviceProvider.CreateScope()) { var...

Require Confirmed Email in ASP.NET Core 2.2 - Part 1

22 Dec 2018 by Ken Haggerty

Scaffold and modify Identity in the new ASP.NET Core 2.2 Razor pages template

Require Confirmed Email in ASP.NET Core 2.2 - Part 2

22 Dec 2018 by Ken Haggerty

Scaffold and modify Identity in the new ASP.NET Core 2.2 Razor pages template

Run EF Core Queries on SQL Server From Blazor WebAssembly

21 Sep 2020 by Jeremy Likness

What if I could write a LINQ query on a client the same way I would on a server, and execute it remotely with minimal configuration, setup, ritual and ceremony?

Same query, multiple dbcontext

12 Mar 2017 by Steve Van Lint

Hello,I created a monitor system for our cloud environments.The environments are individual sites with their own database. Since each site has several tasks running, we need to intercept when a task fails. There are other things I monitor but the idea is the same.The situation is as...

Same query, multiple dbcontext

8 Mar 2017 by Dave Kreskowiak

Yeah, don't use Entity Framework. The problem with using it is that your DbContext is directly tied to the exact version of the database the context was written against. If the database schema changes, the DbContext has to change with it. This prevents you from using the same DbContext against...