I'm trying to access the underlying Database and Connection object from DbContext in order to run some SQL "old style" in a library routine. This library routine uses DbContext as it can be called from many places. This worked in 4.1 however, with 4.3.1 I'm getting errors...
Here's the outline of the relevant code
using (testentities te = new testentities())
{
var result = CallGeneric(te, some parameters);
}
public static Results CallGeneric(DbContext db, some parameters);
{
var connection = (SqlConnection)db.Database.Connection;
// do some stuff here
}
In EF 4.1 this worked and I was able to use the connection directly. I updated to EF 4.3.1 using NuGet and this no longer works. Any ideas on how to get to the underlying connection?
Solution was to uninstall EF 4.1 and then re-install EF 4.3.1
Related
I worked on a asp.net core 1.1 project a while ago and use in projetc AutoMapper.
in asp.net core 1.1, I add services.AddAutoMapper() in startup file :
StartUp file in asp.net core 1.1:
public void ConfigureServices(IServiceCollection services)
{
//Some Code
services.AddMvc();
services.AddAutoMapper();
}
And I use AutoMapper in Controller easily.
Controller :
public async Task<IActionResult> AddEditBook(AddEditBookViewModel model)
{
Book bookmodel = AutoMapper.Mapper.Map<AddEditBookViewModel, Book>(model);
context.books.Add(bookmodel);
context.SaveChanges();
}
And everything was fine.
But I'm currently working on a Asp.net Core 2 project and I get the error with services.AddAutoMapper() in sturtap file.
Error CS0121 The call is ambiguous between the following methods or properties: 'ServiceCollectionExtensions.AddAutoMapper(IServiceCollection, params Assembly[])' and 'ServiceCollectionExtensions.AddAutoMapper(IServiceCollection, params Type[])'
What is the reason for this error?
Also, services.AddAutoMapper in asp.net core 2 has some parameters. what should I send to this parameter?
If you are using AspNet Core 2.2 and AutoMapper.Extensions.Microsoft.DependencyInjection v6.1
You need to use in Startup file
services.AddAutoMapper(typeof(Startup));
You likely updated your ASP.NET Core dependencies, but still using outdated AutoMapper.Extensions.Microsoft.DependencyInjection package.
For ASP.NET Core you need at least Version 3.0.1 from https://www.nuget.org/packages/AutoMapper.Extensions.Microsoft.DependencyInjection/3.0.1
Which references AutoMapper 6.1.1 or higher.
AutoMapper (>= 6.1.1)
Microsoft.Extensions.DependencyInjection.Abstractions (>= 2.0.0)
Microsoft.Extensions.DependencyModel (>= 2.0.0)
The older packages depend on Microsoft.Extensions.DependencyInjection.Abstractions 1.1.0 and can't be used with ASP.NET Core since there have been breaking changes between Microsoft.Extensions.DependencyInjection.Abstractions 1.1.0 and 2.0
In new version (6.1) of AutoMapper.Extensions.Microsoft.DependencyInjection nuget package you should use it as follows:
services.AddAutoMapper(Type assemblyTypeToSearch);
// OR
services.AddAutoMapper(params Type[] assemblyTypesToSearch);
e.g:
services.AddAutoMapper(typeOf(yourClass));
Install package:
Install-Package AutoMapper.Extensions.Microsoft.DependencyInjection -Version 7.0.0
Nuget:
https://www.nuget.org/packages/AutoMapper.Extensions.Microsoft.DependencyInjection/
In Startup Class:
services.AddAutoMapper(typeof(Startup));
None of these worked for me, I have a .NET Core 2.2 project and the complete code for configuring the mapper looks like this(part of ConfigureService() method):
// Auto Mapper Configurations
var mappingConfig = new MapperConfiguration(mc =>
{
mc.AddProfile(new SimpleMappings());
});
IMapper mapper = mappingConfig.CreateMapper();
services.AddSingleton(mapper);
Then I have my Mappings class which I've placed in the BL project:
public class SimpleMappings : Profile
{
public SimpleMappings()
{
CreateMap<DwUser, DwUserDto>();
CreateMap<DwOrganization, DwOrganizationDto>();
}
}
And finally the usage of the mapper looks like this:
public class DwUserService : IDwUserService
{
private readonly IDwUserRepository _dwUserRepository;
private readonly IMapper _mapper;
public DwUserService(IDwUserRepository dwUserRepository, IMapper mapper)
{
_dwUserRepository = dwUserRepository;
_mapper = mapper;
}
public async Task<DwUserDto> GetByUsernameAndOrgAsync(string username, string org)
{
var dwUser = await _dwUserRepository.GetByUsernameAndOrgAsync(username, org).ConfigureAwait(false);
var dwUserDto = _mapper.Map<DwUserDto>(dwUser);
return dwUserDto;
}
}
Here is a similar link on the same topic:
How to setup Automapper in ASP.NET Core
If you are using AspNet Core 2.2.Try changing your code
from:
services.AddAutoMapper();
to:
services.AddAutoMapper(typeof(Startup));
It worked for me.
In .Net 6, you can do it like
builder.Services.AddAutoMapper(typeof(Program).Assembly); // Since there is no Startup file
OR
builder.Services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());
Basically, it requires the assembly name as shown in screenshot below
I solved this by creating a class that inherits AutoMapper.Profile
public class model_to_resource_profile : Profile
{
public model_to_resource_profile()
{
CreateMap<your_model_class, your_model_resource_class>();
}
}
And adding this line in the Startup.cs:
services.AddAutoMapper(typeof(model_to_resource_profile ));
try this, works with 2.1 and up, i have not used any previous version so can't tell.
services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());
The official docs:
https://automapper.readthedocs.io/en/latest/Dependency-injection.html#asp-net-core
You define the configuration using profiles. And then you let
AutoMapper know in what assemblies are those profiles defined by
calling the IServiceCollection extension method AddAutoMapper at
startup:
services.AddAutoMapper(profileAssembly1, profileAssembly2 /*, ...*/);
or marker types:
services.AddAutoMapper(typeof(ProfileTypeFromAssembly1), typeof(ProfileTypeFromAssembly2) /*, ...*/);
If you are having issue with adding your auto mapper, It is better you check through the type and version you added.
If it is not "AutoMapper.Extensions.Microsoft.DependencyInjection", then you won't be able to use "services.AddAutoMapper()".
Sometimes, you might mistakenly add "AutoMapper
Dec 6th 2019 Based upon initial attempt in a pluralsight course Building an API with ASP.NET Core by Shawn Wildermuth. As I got the error "...ambiguous 'ServiceCollectionExtensions.AddAutoMapper(IServiceCollection, params Assembly[])..."
I started researching proper syntax to implement AddAutoMapper in Core 2.2. My NuGet reference is version 7.0.0 After the tutorial had me create the Profile class in my Data repository directory which additionally referenced my model nir weiner & dev-siberia's answers above led me to trying to reference the profile class in the Startup.ConfigureServices() by name:
services.AddAutoMapper(typeof(CampProfile));
the content of the profile class is just a (no pun intended) old school map of the data class and the model in its constructor
this.CreateMap<Camp, CampModel>();
This addressed the poor lack of documentation for this current version.
Respectfully,
ChristianProgrammer
I'm trying to use paging (that is .Skip(...).Take(...) in Entity Framework 7. It works OK with Microsoft SQL Server 2012 and 2014, but fails with the following error on SQL Server 2008:
System.Data.SqlClient.SqlException (0x80131904): Incorrect syntax near 'OFFSET'. Invalid usage of the option NEXT in the FETCH statement.
I've figured out that it is a breaking change in EF version 6.1.2 (http://erikej.blogspot.com/2014/12/a-breaking-change-in-entity-framework.html). But the fix is to modify EDMX file setting ProviderManifestToken attribute to "2008".
The problem is that EF7 currently only supports code-first scenario, thus there is no any EDMX out there. The question is: how to configure ASP.NET 5 website with Entity Framework 7 to use fallback pagination approach for SQL Server older than 2012?
If you use Edmx file, you must open the edmx file using XML Editor and change
ProviderManifestToken="2012" ==> ProviderManifestToken="2008"
in line 7.
Please take a look at this blog post for more information:
http://erikej.blogspot.com.tr/2014/12/a-breaking-change-in-entity-framework.html
I encountered this problem myself using EF 7 and sql server 2008. Fortunately in the latest rc1 version of EF 7 you can solve this by using .UseRowNumberForPaging() as shown in this example:
services.AddEntityFramework()
.AddSqlServer()
.AddDbContext<YourDbContext>(options =>
options.UseSqlServer(configuration["Data:DefaultConnection:ConnectionString"])
// this is needed unless you are on mssql 2012 or higher
.UseRowNumberForPaging()
);
It's broken in RC 1. Gotta wait to get RC 2.
https://github.com/aspnet/EntityFramework/issues/4616
This feature was removed in EF Core 3.x, UseRowNumberForPaging is marked as obsolete. However, you can use EfCore3.SqlServer2008Query package instead. There are 2 packages available in Nuget, one for >= .NET 5.0, other one is for >= .NET 3.1
Usage:
services.AddDbContext<MyDbContext>(o =>
o.UseSqlServer(Configuration.GetConnectionString("Default"))
.ReplaceService<IQueryTranslationPostprocessorFactory, SqlServer2008QueryTranslationPostprocessorFactory>());
MyDbConnectionString is Connection string from any source
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer(_config["MyDbConnectionString"],
options=>
{
options.UseRowNumberForPaging();
});
}
UseRowNumberForPaging() solved issue in any case except for edmx file scenario.
You need to use something like this :
var MinPageRank = (pageIndex - 1) * pageSize + 1;
var MaxPageRank = (pageIndex * pageSize);
var person = _context.Person.FromSql($"SELECT * FROM (SELECT [RANK] = ROW_NUMBER() OVER (ORDER BY Surname),* FROM Person) A WHERE A.[RANK] BETWEEN {MinPageRank} AND {MaxPageRank}").ToList();
IQueryable<Person> PersonIQ = from s in person.AsQueryable() select s;
Person = await PaginatedList<Person>.CreateAsync(PersonIQ .AsNoTracking(), pageIndex ?? 1, pageSize, sourceFull);
Here, just set UseRowNumberForPaging() in ConfigureServices
services.AddDbContext<CallcContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("Connectionstring"),opt=> { opt.UseRowNumberForPaging(); }));
Guys I am trying to learn MVC and I want to use stored procedures to perform all CRUD operations in MVC framework. I have googled for tutorials and everything, but all the tutorials are using that "Code-First" approach and using Entity Framework to handle all the data.
I would really appreciate if someone could help me regarding how to use SP in MVC and could provide some links to tutorials or something like that.
Before you learn Entity Framework, before you learn LINQ to SQL, take the time to learn ADO.NET which is all you need if you want to call a stored procedure. The previously mentioned technologies are in fact built on top of ADO.NET so it's good to know what they are doing. Check out lesson 7 of this tutorial which shows you exactly how to call a stored procedure from any .NET application (including MVC).
You can always use code first from your db
Code First to an Existing Database
Using this simple method, I was able to call stored procedures in MVC application
public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText, SqlParameter[] commandParameters)
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
using (SqlCommand command = new SqlCommand())
{
command.Connection = connection;
command.CommandTimeout = 0;
command.CommandType = commandType;
command.CommandText = commandText;
if (commandParameters != null && commandParameters.Length > 0)
command.Parameters.AddRange(commandParameters);
return FillData(command, connection);
}
}
}
MVC3 EF5. It's running well. But when I update model from database, builds successfully but I got the exception above on the last line. When I last updated from database it was 2-3 months ago, and it was fine.
public static ObjectContext GetContext()
{
Assembly testAssembly = Assembly.GetExecutingAssembly();
Type calcType = testAssembly.GetType("Model.Entities");
return (ObjectContext)Activator.CreateInstance(calcType);
}
Newer versions of Entity Framework provide DbContext, as opposed to the ObjectContext that was <= EF 4.0. However, it is still possible to return a reference to the ObjectContext via IObjectContextAdapter
Assembly testAssembly = Assembly.GetExecutingAssembly();
Type calcType = testAssembly.GetType("Model.Entities");
var entities = (DbContext)(Activator.CreateInstance(calcType));
return ((IObjectContextAdapter)entities).ObjectContext;
Personally however, I would instead look at upgrading your code to return the DbContext, as it is more advanced.
Background:
From another question here at SO I have a Winforms solution (Finance) with many projects (fixed projects for the solution).
Now one of my customers asked me to "upgrade" the solution and add projects/modules that will come from another Winforms solution (HR).
I really don't want to keep these projects as fixed projects on the existing finance solution. For that I'm trying to create plugins that will load GUI, business logic and the data layer all using MEF.
Question:
I have a context (DbContext built to implment the Generic Repository Pattern) with a list of external contexts (loaded using MEF - these contexts represent the contexts from each plugin, also with the Generic Repository Pattern).
Let's say I have this:
public class MainContext : DbContext
{
public List<IPluginContext> ExternalContexts { get; set; }
// other stuff here
}
and
public class PluginContext_A : DbContext, IPluginContext
{ /* Items from this context */ }
public class PluginContext_B : DbContext, IPluginContext
{ /* Items from this context */ }
and within the MainContext class, already loaded, I have both external contexts (from plugins).
With that in mind, let's say I have a transaction that will impact both the MainContext and the PluginContext_B.
How to perform update/insert/delete on both contexts within one transaction (unity of work)?
Using the IUnityOfWork I can set the SaveChanges() for the last item but as far as I know I must have a single context for it to work as a single transaction.
There's a way using the MSDTC (TransactionScope) but this approach is terrible and I'd reather not use this at all (also because I need to enable MSDTC on clients and server and I've had crashes and leaks all the time).
Update:
Systems are using SQL 2008 R2. Never bellow.
If it's possible to use TransactionScope in a way that won't scale to MSDTC it's fine, but I've never achieved that. All the time I've used TransactionScope it goes into MSDTC. According to another post on SO, there are some cases where TS will not go into MSDTC: check here. But I'd really prefer to go into some other way instead of TransactionScope...
If you are using multiple contexts each using separate connection and you want to save data to those context in single transaction you must use TransactionScope with distributed transaction (MSDTC).
Your linked question is not that case because in that scenario first connection do not modify data so it can be closed prior to starting the connection where data are modified. In your case data are concurrently modified on multiple connection which requires two-phase commit and MSDTC.
You can try to solve it with sharing single connection among multiple contexts but that can be quite tricky. I'm not sure how reliable the following sample is but you can give it a try:
using (var connection = new SqlConnection(connnectionString))
{
var c1 = new Context(connection);
var c2 = new Context(connection);
c1.MyEntities.Add(new MyEntity() { Name = "A" });
c2.MyEntities.Add(new MyEntity() { Name = "B" });
connection.Open();
using (var scope = new TransactionScope())
{
// This is necessary because DbContext doesnt't contain necessary methods
ObjectContext obj1 = ((IObjectContextAdapter)c1).ObjectContext;
obj1.SaveChanges(SaveOptions.DetectChangesBeforeSave);
ObjectContext obj2 = ((IObjectContextAdapter)c2).ObjectContext;
obj2.SaveChanges(SaveOptions.DetectChangesBeforeSave);
scope.Complete();
// Only after successful commit of both save operations we can accept changes
// otherwise in rollback caused by second context the changes from the first
// context will be already accepted = lost
obj1.AcceptAllChanges();
obj2.AcceptAllChanges();
}
}
Context constructor is defined as:
public Context(DbConnection connection) : base(connection,false) { }
The sample itself worked for me but it has multiple problems:
First usage of contexts must be done with closed connection. That is the reason why I'm adding entities prior to opening the connection.
I rather open connection manually outside of the transaction but perhaps it is not needed.
Both save changes successfully run and Transaction.Current has empty distributed transaction Id so it should be still local.
The saving is much more complicated and you must use ObjectContext because DbContext doesn't have all necessary methods.
It doesn't have to work in every scenario. Even MSDN claims this:
Promotion of a transaction to a DTC may occur when a connection is
closed and reopened within a single transaction. Because the Entity
Framework opens and closes the connection automatically, you should
consider manually opening and closing the connection to avoid
transaction promotion.
The problem with DbContext API is that it closes and reopens connection even if you open it manually so it is a opened question if API always correctly identifies if it runs in the context of transaction and do not close connection.
#Ladislav Mrnka
You were right from the start: I have to use MSDTC.
I've tried multiple things here including the sample code I've provided.
I've tested it many times with changed hare and there but it won't work. The error goes deep into how EF and DbContext works and for that to change I'd finally find myself with my very own ORM tool. It's not the case.
I've also talked to a friend (MVP) that know a lot about EF too.
We have tested some other things here but it won't work the way I want it to. I'll end up with multiple isolated transactions (I was trying to get them together with my sample code) and with this approach I don't have any way to enforce a full rollback automatically and I'll have to create a lot of generic/custom code to manually rollback changes and here comes another question: what if this sort of rollback fails (it's not a rollback, just an update)?
So, the only way we found here is to use the MSDTC and build some tools to help debug/test if DTC is enabled, if client/server firewalls are ok and all that stuff.
Thanks anyway.
=)
So, any chance this has changed by October 19th? All over the intertubes, people suggest the following code, and it doesn't work:
(_contextA as IObjectContextAdapter).ObjectContext.Connection.Open();
(_contextB as IObjectContextAdapter).ObjectContext.Connection.Open();
using (var transaction = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions{IsolationLevel = IsolationLevel.ReadUncommitted, Timeout = TimeSpan.MaxValue}))
{
_contextA.SaveChanges();
_contextB.SaveChanges();
// Commit the transaction
transaction.Complete();
}
// Close open connections
(_contextA as IObjectContextAdapter).ObjectContext.Connection.Close();
(_contextB as IObjectContextAdapter).ObjectContext.Connection.Close();
This is a serious drag for implementing a single Unit of Work class across repositories. Any new way around this?
To avoid using MSDTC (distributed transaction):
This should force you to use one connection within the transaction as well as just one transaction. It should throw an exception otherwise.
Note: At least EF6 is required
class TransactionsExample
{
static void UsingExternalTransaction()
{
using (var conn = new SqlConnection("..."))
{
conn.Open();
using (var sqlTxn = conn.BeginTransaction(System.Data.IsolationLevel.Snapshot))
{
try
{
var sqlCommand = new SqlCommand();
sqlCommand.Connection = conn;
sqlCommand.Transaction = sqlTxn;
sqlCommand.CommandText =
#"UPDATE Blogs SET Rating = 5" +
" WHERE Name LIKE '%Entity Framework%'";
sqlCommand.ExecuteNonQuery();
using (var context =
new BloggingContext(conn, contextOwnsConnection: false))
{
context.Database.UseTransaction(sqlTxn);
var query = context.Posts.Where(p => p.Blog.Rating >= 5);
foreach (var post in query)
{
post.Title += "[Cool Blog]";
}
context.SaveChanges();
}
sqlTxn.Commit();
}
catch (Exception)
{
sqlTxn.Rollback();
}
}
}
}
}
Source:
http://msdn.microsoft.com/en-us/data/dn456843.aspx#existing