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);
}
}
}
Related
I'm aware that there are some commercial libraries and that there's AddRange, but AFAIK AddRange does piecemeal INSERTs under the hood.
I'm looking for a free utility that I can use to add a collection of new entities all at the same time - does one exist for EF6?
I would suggest you take a look at N.EntityFramework.Extension. It is a basic bulk extension framework for EF 6 that is available on Nuget and the source code is available on Github under MIT license.
Install-Package N.EntityFramework.Extensions
https://www.nuget.org/packages/N.EntityFramework.Extensions
Once you install it you can simply use BulkInsert() method directly on the DbContext instance. It support BulkDelete, BulkInsert, BulkMerge and more.
BulkDelete()
var dbcontext = new MyDbContext();
var orders = dbcontext.Orders.Where(o => o.TotalPrice < 5.35M);
dbcontext.BulkDelete(orders);
BulkInsert()
var dbcontext = new MyDbContext();
var orders = new List<Order>();
for(int i=0; i<10000; i++)
{
orders.Add(new Order { OrderDate = DateTime.UtcNow, TotalPrice = 2.99 });
}
dbcontext.BulkInsert(orders);
You can use the following library:
https://github.com/MikaelEliasson/EntityFramework.Utilities
It works well for simple bulk inserts and updates.
You should also look at the following post if you want to find out about other options to achieve bulk insert:
Fastest Way of Inserting in Entity Framework
I am building an ASP.NET MVC application using the Repository pattern. A typical method in my Repository is as follows
public IList<T> Select<T>(string cacheKey, string Sql, object filter) where T: new()
{
IList<T> items = MemoryCache.Default.Get(cacheKey) as IList<T>;
if (items == null || !items.Any())
{
items = Connection.Select<T>(Sql, filter);
MemoryCache.Default.Add(cacheKey, items, DateTime.Now.AddMinutes(120));
}
return items;
}
and it is being used as follows
IEnumerable<OSADCOL> osadcols = Repository.Select<OSADCOL>("OSADCOLS__TblId=" + Id, "TBLid = #id", new { id = Id });
In the above mentioned example OSADCOL is a model in my app and represents a Table with the same name in my Database. The Connection.Select function is ORMlite function. I don't use Entity Framework for performance issues. My problem is the following. I am currently cashing the result set for future relevance but I am doing it in a hard coded way. I am caching the result set for 2 hours. It is obvious that a proper implementation would be to discard my cashed data when the OSADCOL's table data changes. It seems that I have to use SQLDependency or SQLCacheDependency. The questions are the following:
How am I going to use SQLDependency or SQLCacheDependency with this Repository?
What is the actual difference between these 2?
It is mentioned in some forums that SQLDependency creates memory leaks? Is that true? And If yes is there an alternative approach?
Any Ideas?
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
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
In EF4, this was not easily possible. You either had to degrade to classic ADO.NET (DataReader), use ObjectContext.Translate or use the EFExtensions project.
Has this been implemented off the shelf in EF CTP5?
If not, what is the recommended way of doing this?
Do we have to cast the DbContext<T> as an IObjectContextAdapter and access the underlying ObjectContext in order to get to this method?
Can someone point me to a good article on doing this with EF CTP5?
So i got this working, here's what i have:
internal SomeInternalPOCOWrapper FindXXX(string xxx)
{
Condition.Requires(xxx).IsNotNullOrEmpty();
var someInternalPokey = new SomeInternalPOCOWrapper();
var ctx = (this as IObjectContextAdapter).ObjectContext;
var con = new SqlConnection("xxxxx");
{
con.Open();
DbCommand cmd = con.CreateCommand();
cmd.CommandText = "exec dbo.usp_XXX #xxxx";
cmd.Parameters.Add(new SqlParameter("xxxx", xxx));
using (var rdr = cmd.ExecuteReader())
{
// -- RESULT SET #1
someInternalPokey.Prop1 = ctx.Translate<InternalPoco1>(rdr);
// -- RESULT SET #2
rdr.NextResult();
someInternalPokey.Prop2 = ctx.Translate<InternalPoco2>(rdr);
// -- RESULT SET #3
rdr.NextResult();
someInternalPokey.Prop3 = ctx.Translate<InternalPoco3>(rdr);
// RESULT SET #4
rdr.NextResult();
someInternalPokey.Prop4 = ctx.Translate<InternalPoco4>(rdr);
}
con.Close();
}
return someInternalPokey;
}
Essentially, it's basically like classic ADO.NET. You read the DbReader, advance to the next result set, etc.
But at least we have the Translate method which seemingly does a left-to-right between the result set fields and the supplied entity.
Note the method is internal.
My Repository calls this method, then hydrates the DTO into my domain objects.
I'm not 100% happy with it for 3 reasons:
We have to cast the DbContext as IObjectContextAdapter. The method Translate should be on DbContext<T> class IMO.
We have to use classic ADO.NET Objects. Why? Stored Procedures are a must have for any ORM. My main gripe with EF is the lack of the stored procedure support and this seems to not have been rectified with EF CTP5.
You have to open a new SqlConnection. Why can't it use the same connection as the one opened by the EF Context?
Hope this both helps someone and sends out a message to the EF team. We need multiple result support for SPROCS off the shelf. You can map a stored proc to a complex type, so why can't we map a stored proc to multiple complex types?