System.TypeLoadException: Method 'Create' in type 'MySql.Data.EntityFrameworkCore.Query.Internal.MySQLSqlTranslatingExpressionVisitorFactory'

Question

I'm trying to add a new user to the database with the following code:

public async void SeedUsers(){
    int count=0;
    if(count>0){
        return;
    }
    else{
        string email="[email protected]";
        _context.Add(new User{LoginEmail=email});  
        await _context.SaveChangesAsync();  
    }
}

But it keeps giving me the following error:

System.TypeLoadException: Method 'Create' in type 'MySql.Data.EntityFrameworkCore.Query.Internal.MySQLSqlTranslatingExpressionVisitorFactory' from >assembly 'MySql.Data.EntityFrameworkCore, Version=8.0.22.0, Culture=neutral, >PublicKeyToken=c5687fc88969c44d' does not have an implementation. at MySql.Data.EntityFrameworkCore.Extensions.MySQLServiceCollectionExtensions.AddEntityFrameworkMySQL(IServ>iceCollection services) at MySql.Data.EntityFrameworkCore.Infrastructure.Internal.MySQLOptionsExtension.ApplyServices(IServiceColle>ction services) at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.ApplyServices(IDbContextOptions >options, ServiceCollection services) at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<c__DisplayClass4_0.g__BuildServiceProvider|3() at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<>c__DisplayClass4_0.b__2(Int64 k) at System.Collections.Concurrent.ConcurrentDictionary2.GetOrAdd(TKey key, Func2 valueFactory) at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.GetOrAdd(IDbContextOptions options, >Boolean providerRequired) at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider() at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies() at Microsoft.EntityFrameworkCore.DbContext.EntryWithoutDetectChanges[TEntity](TEntity entity) at Microsoft.EntityFrameworkCore.DbContext.SetEntityState[TEntity](TEntity entity, EntityState >entityState) at Microsoft.EntityFrameworkCore.DbContext.Add[TEntity](TEntity entity) at contatinApi.Data.SeedData.SeedUsers() in D:\dev\contatinapi\Data\SeedData.cs:line 24 at System.Threading.Tasks.Task.<>c.b__139_1(Object state) at System.Threading.QueueUserWorkItemCallback.<>c.<.cctor>b__6_0(QueueUserWorkItemCallback quwi) at System.Threading.ExecutionContext.RunForThreadPoolUnsafe[TState](ExecutionContext >executionContext, Action`1 callback, TState& state) at System.Threading.QueueUserWorkItemCallback.Execute() at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

The User class:

public class User
    {
        public int Id{get;set;}
        public string LoginEmail{get;set;}
        public string UserName{get;set;}
        public DateTime CreatedAt{get;set;}
        public List<Contact> Contacts {get;set;}
        public List<ContactList> ContactLists{get;set;}
    }

Both the EF Core and MySQL packages are updated. Also, i tried using stored procedures and it gave the same results.

The content of Ex was:

The value of Ex was {System.TypeLoadException: Method 'Create' in type 'MySql.Data.EntityFrameworkCore.Query.Internal.MySQLSqlTranslatingExpressionVisitorFactory' from assembly 'MySql.Data.EntityFrameworkCore, Version=8.0.22.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' does not have an implementation. at MySql.Data.EntityFrameworkCore.Extensions.MySQLServiceCollectionExtensions.AddEntityFrameworkMySQL(IServiceCollection services) at MySql.Data.EntityFrameworkCore.Infrastructure.Internal.MySQLOptionsExtension.ApplyServices(IServiceCollection services) at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.ApplyServices(IDbContextOptions options, ServiceCollection services) at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<>c__DisplayClass4_0.g__BuildServiceProvider|3() at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<>c__DisplayClass4_0.b__2(Int64 k) at System.Collections.Concurrent.ConcurrentDictionary2.GetOrAdd(TKey key, Func2 valueFactory) at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.GetOrAdd(IDbContextOptions options, Boolean providerRequired) at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider() at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies() at Microsoft.EntityFrameworkCore.DbContext.Microsoft.EntityFrameworkCore.Internal.IDbContextDependencies.get_StateManager() at Microsoft.EntityFrameworkCore.Internal.InternalDbSet1.EntryWithoutDetectChanges(TEntity entity) at Microsoft.EntityFrameworkCore.Internal.InternalDbSet1.Add(TEntity entity) at contatinApi.Data.SeedData.SeedUsers() in D:\dev\ContatinApi\Data\SeedData.cs:line 40}

Solution 1

If you're using Microsoft.EntityFrameworkCore 5.0 downgrade it to Microsoft.EntityFrameworkCore 3.1.10 MySQL EF 8.0.22 is currently not compatiable with Microsoft.EntityFrameworkCore 5.0

I have a working Code until I upgraded to Microsoft.EntityFrameworkCore 5.0 then I got same error, Downgraded and it worked!

Hoping to post a Bug report on MySQL Bug Forum

Solution 2

I have resolved this issue following this:-

1. upgrade Microsoft.EntityFrameworkCore to version 5.0.1

2. upgrade Pomelo.EntityFrameworkCore.MySql to version 5.0.0-alpha.2

3. add the code blocks into ConfigureServices method of Startup.cs file

   var connectionString = _configuration.GetConnectionString("userDB"); services.AddDbContext(options =>
   options.UseMySql(connectionString,new MySqlServerVersion(new Version(10, 1, 40)), mySqlOptions => mySqlOptions .CharSetBehavior(CharSetBehavior.NeverAppend)));

To get mysql server version run the query to any of mysql server editor like MySql Workbench or HeidiSQL

SELECT VERSION()

Solution 3

While following an EF Core tutorial for MySql using Migrations and getting the error "Method 'Create' does not have an implementation" and lots of Googling, I Downgraded my csproj file from net5.0 to netcoreapp3.1:

<TargetFramework>netcoreapp3.1</TargetFramework>

And included the following Nuget packages using terminal dotnet commands inside the project directory:

dotnet add package Pomelo.EntityFrameworkCore.MySql --version 5.0.0-alpha.2
...

dotnet list package                    
    Project 'XYZ' has the following package references
       [netcoreapp3.1]: 
       Top-level Package                           Requested       Resolved     
       > Microsoft.EntityFrameworkCore             5.0.1           5.0.1        
       > Microsoft.EntityFrameworkCore.Design      5.0.1           5.0.1        
       > Microsoft.EntityFrameworkCore.Tools       5.0.1           5.0.1        
       > Pomelo.EntityFrameworkCore.MySql          5.0.0-alpha.2   5.0.0-alpha.2

As example, one of the model files is Student.cs:

namespace EFCoreTutorial.Model
{
    public class Student
    {
        public int StudentId { get; set; }
        public string Name { get; set; }
    }
}

I created the db context file SchoolContext.cs with my personal connection string as:

using Microsoft.EntityFrameworkCore;
using Pomelo.EntityFrameworkCore.MySql.Infrastructure;

namespace EFCoreTutorial.Data
{
  public class SchoolContext : DbContext
  {
    public DbSet<Model.Student> Students { get; set; }
    public DbSet<Model.Course> Courses { get; set; }
        
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
      string connectionString = "server=localhost;port=3306;database=SchoolDB;user=root;password=******";
      optionsBuilder.UseMySql(connectionString, new MySqlServerVersion(new System.Version(8, 0, 22)), mySqlOptions => mySqlOptions.CharSetBehavior(CharSetBehavior.NeverAppend));
    }
  }
}

then you can create the database and the empty tables defined in the Model with

dotnet ef migrations add CreateSchoolDB <- just a label 
dotnet ef migrations list   <- to verify it is pending
dotnet ef database update   <- the database will be created/updated
dotnet ef migrations list   <- to verify

finally verify in mysql:

mysql> show databases;
mysql> use SchoolDB;
mysql> show tables;

Succes! The Database and tables were completely created from the models and DB Context definition.

Comments

[Pedro Lucas Maia Ramos]

The Id field(key) is set to auto increment directly into the database and there's no required fields in the user class.

[Serge]

What about public DateTime CreatedAt{get;set;} . Can it be null? it should be public DateTime? CreatedAt{get;set;} or you have to assign date

[Pedro Lucas Maia Ramos]

It's also added directly into the database. I added them into de object and still got an error.

[Serge]

What do you mean by "It's also added directly into the database. " and did you change _context.Add(newUser) to _context.Users.Add(newUser)?

[Pedro Lucas Maia Ramos]

I changed to _context.Users.Add and still got the error. In the database, the field createdAt has the default value of Now().

[Serge]

This default values are very tricky. In order to trigger default value you have to post null value. DateTime by default has a very strange date so you have to change your class property to DateTime? or assign the real value before adding.

[Pedro Lucas Maia Ramos]

I tried using DateTime.Now on the object and still got the same error. Could it be the navigation properties(Contacts and ContactLists)?

[Serge]

I don't think so. I've used Add() for thousand times and it always worked. Did you try to get users? Maybe it's problem with _context?

[Serge]

I updated code. Pls run it in debuger and check var ex

[Pedro Lucas Maia Ramos]

Updated the question, ex value was exactly the same error.

[Pedro Lucas Maia Ramos]

Still same error. Could it be the MySQL package not being compatible with the current version of EF Core?

[Serge]

I am sorry but I can't help you. I've never worked with MySql and will never recomend this DB to anybody. I prefer the professional applications not open source. EF core were created by Microsoft and for MS SQL mostly.

[Serge]

I noticed that your User class doesn't have any attributes? Can you post your DB context USER part ?

[Mark G]

The Pomelo provider for MySQL has prerelease support for EF Core 5.0 if you'd like to try that.

[Snipe3000]

@MarkG I'm using Pomelo.EntityFrameworkCore.MySql 5.0.0-alpha.2 build. The same problem is still there.

[Mark G]

Make sure you're using UseMySql() instead of UseMySQL() if you still have a reference to MySql.Data.EntityFrameworkCore in your project file.