I have an existing asp.net website that uses an SqlConnection.
I have added the ADO.net Entity Framework.
I have successfully connected to the database and created the .edmx file.
I am able to connect through the Entity Framework with the connectionstring that is automatically generated.
I want to use the existing SqlConnection object that I use throughout the site for the Entity Framework connection.
I do not want to have to use a second database connection for the one page that is going to use the ADO.net Entity Framework and I don’t want to change the entire site to use the new Entity Framework connection string.
Thanks for any help you can provide.
That forum post has the answer:
MetadataWorkspace workspace = new MetadataWorkspace(
new string[] { "res://*/" },
new Assembly[] { Assembly.GetExecutingAssembly() });
using (SqlConnection sqlConnection = new SqlConnection(connectionString))
using (EntityConnection entityConnection = new EntityConnection(workspace, sqlConnection))
using (NorthwindEntities context = new NorthwindEntities(entityConnection))
{
foreach (var product in context.Products)
{
Console.WriteLine(product.ProductName);
}
}
"res://*/" is the part of your EF connection string that describes the location of your xml mapping files - in this case embedded resources in the current assembly.
You can do this by using the constructor of your generated ObjectContext that accepts an EntityConnection. When you create the EntityConnection you pass in your SqlConnection.
Andrew Peters,
Thank you for your answer.
I have been going around and around with the System.Data.EntityClient.EntityConnection.
It’s right there at my finger tips but I cannot seem to get the MetadataWorkspace parameter to work.
This is the closest example I have found (the post marked Answer):
http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/dd7b1c41-e428-4e29-ab83-448d3f529ba4/
Thanks for any help.
Related
Using an EF model in the Models folder in my MVC 4 project, I succeeded to display data in a razor view using a coded class named Prod and a controller method as next:
public ActionResult Index()
{
IEnumerable<Prod> Pr = from p in db.Products
select new Prod
{
ProductId = p.ProductID,
ProductName = p.ProductName
};
return View(Pr);
}
Now I am trying to do the same thing using a model in a class library instead of the current one, so I added to my solution a new class library, added then a model using the same connection string, and mapping the same entities, then added to my MVC project a reference to the new class library, and put at the top of both MyController and Prod class the next:
using MyClassLibrary;
Then I deleted the old model, now when I try to display the view, I get the following error:
Unable to load the specified metadata resource.
Any help please ?
When you move or rename the project the data context (.edmx) is in the metadata part of the Entity Framework connection string has to change
you can try have
connectionString="metadata=res://*/MyModel.csdl|res://*/MyModel.ssdl|res://*/MyModel.msl;
instead of
connectionString="metadata=res://*/Models.MyModel.csdl|res://*/Models.MyModel.ssdl|res://*/Models.MyModel.msl;
or try deleting your context and recreating it then check the connection string it adds automatically.
You need to put your connectionstring in web.config in Mc4 web project
You need to Mention the datasource in the connection string.
If you have not used any other web.config file for views. Use you generic web.config file and upload a connection string with New datasource name , user and password.
I have a solution consisting of 4 projects. MVC, WCF, Business LYR, DataAcess. I am using entity framework for database transaction. My requirement is that i want to fetch the entity connectionstring only from MVC webconfig without refering in APP.cofig of acess layer. Is it possible in this scenario?
While I tried the following code I got an error.
this.ConnectionString="data source=cmh-sosql;initial catalog=Student;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework";
System.Data.SqlClient.SqlConnectionStringBuilder scsb = new System.Data.SqlClient.SqlConnectionStringBuilder(this.ConnectionString);
EntityConnectionStringBuilder ecb = new EntityConnectionStringBuilder();
ecb.Metadata = "res://*/schoolModel.csdl|res://*/schoolModel.ssdl|res://*/schoolModel.msl";
ecb.Provider = "System.Data.SqlClient";
ecb.ProviderConnectionString = scsb.ConnectionString;
using (SchoolDB schoolDB = new SchoolDB(ecb.ConnectionString))
Error: The entity type student is not part of the model for the current context.
You are absolutely correct. I got the solution. There is no need to keep any string in webconfig for reference to a entity model. We can use the above code for reference it. But the change is to configure the context object.
public SchoolDB(string connectionString)
: base(connectionString)
{
}
We need to change the constructor also by this format.
thanks Sampath
I can't find how my connectionString syntax is wrong. Can anyone suggest a way to figure this out? I am having a difficulty using EF with my connection string. I am new to EF.
I am using Sybase Anywhere 12 database.
I'm using the Table-First ObjectContext with EDMX in a separate class library refenced by a web application.
I'm using a Ninject Module in my class library to bind my repositories.
I'm using a ODBC DataStore called "Test"
Other information EF 4.3.1.0, .NET 4, VS2010
My main web application web.config has the EF connection string copied to it as:
<connectionStrings>
<add name="Entities"connectionString="metadata=res://*/MyEntities.csdl|res://*/MyEntities.ssdl|res://*/MyEntities.msl;provider=iAnywhere.Data.SQLAnywhere;provider connection string="UserID=aUser;Password=aPassword;DataSourceName=Test"" providerName="iAnywhere.Data.SQLAnywhere"/>
</connectionStrings>
When I initialize my Entity/ObjectContext in my Repository (see using statement below) it returns an error: "The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid."
using (var context = new Entities())
{
return {Linq to Entity here}
}
I turned on CLR exceptions on the debugger and found the code throws the error in the .NET Framework here:
EntityConnection.cs
effectiveConnectionOptions = new DbConnectionOptions(setting.ConnectionString, EntityConnectionStringBuilder.Synonyms, false);
edmx designer generated:
/// <summary>
/// Initializes a new Entities object using the connection string found in the 'Entities' section of the application configuration file.
/// </summary>
public Entities() : base("name=Entities", "Entities")
{
this.ContextOptions.LazyLoadingEnabled = true;
OnContextCreated();
}
I can see my connection string there, so it is having a difficult time parsing the connectionString. I have tried many different permutations of syntax and haven't found anything it accepts including:
Explicitly naming the assembly for entity files instead of a wildcard(e.g. metadata=res://MyDomain/MyEntities.csdl...)
Using Sybase friendly ODBC attributes such as UID instead of UserID, PWD instead of Password, and DBN instead of DataSourceName.
Thanks.
I got everything working and the only reason I can think of is that I deleted my ASP .NET 4.0 temp files. Also, I must add I changed my process from using an integration test to test this piece to using a unit test. I did not do unit tests first, because our build server does not have a database on it.
Once I was able to prove that it was working there, I decided to delete my temp files. After that, everything started working properly. So, some sort of cache issue was occurring in my application. I used the same connectionString that I mentioned above.
Actually, I used the domain name of the Metadata "metadata=res://MyDomain/MyEntitities.csdl" rather than */MyEntities.csdl. I don't plan on changing the domain any time soon. In fact, that is just what may have caused some of the issue, because I had changed the location, name, and namespace of MyEntities.Domain where the EF was.
EF CTP 5. I have a single instance where I would like to get the unproxied entity. I can't seem to find a way to do this. I don't want to disable proxy creation all together, just need it for this one query. Can anyone help?
Here is a simple example:
var myEntity = DbContext.Entities.Find(1);
var unproxy = myEntity...?
I believe the only possibility is to create new instance of DbContext and turn proxy creation off just to execute this query. The reason is that DynamicProxy is type created in runtime which derives from your original entity type and adds tracking and lazy loading functionality. You can't strip the proxy away once you created it this way. Try this:
using (var context = new MyDbContext(connectionString))
{
((IObjectContextAdapter)context).ObjectContext.ContextOptions.ProxyCreationEnabled = false;
var myEntity = context.Entities.Find(1);
}
In Asp.Net Core you can use AsNoTracking().
Eg:
var blogs = context.Blogs
.AsNoTracking()
.ToList();
More info you can find here.
I am using EF4 Self Tracking Entities (VS2010 Beta 2 CTP 2 plus new T4 generator). But when I try to update entity information it does not update to database as expected.
I setup 2 service calls. one for GetResource(int id) which return a resource object. the second call is SaveResource(Resource res); here is the code.
public Resource GetResource(int id)
{
using (var dc = new MyEntities())
{
return dc.Resources.Where(d => d.ResourceId == id).SingleOrDefault();
}
}
public void SaveResource(Resource res)
{
using (var dc = new MyEntities())
{
dc.Resources.ApplyChanges(res);
dc.SaveChanges();
// Nothing save to database.
}
}
//Windows Console Client Calls
var res = service.GetResource(1);
res.Description = "New Change"; // Not updating...
service.SaveResource(res);
// does not change anything.
It seems to me that ChangeTracker.State is always show as "Unchanged".
anything wrong in this code?
This is probably a long shot... but:
I assume your Service is actually in another Tier? If you are testing in the same tier you will have problems.
Self Tracking Entities (STEs) don't record changes until when they are connected to an ObjectContext, the idea is that if they are connected to a ObjectContext it can record changes for them and there is no point doing the same work twice.
STEs start tracking once they are deserialized on the client using WCF, i.e. once they are materialized to a tier without an ObjectContext.
If you look through the generated code you should be able to see how to turn tracking on manually too.
Hope this helps
Alex
You have to share assembly with STEs between client and service - that is the main point. Then when adding service reference make sure that "Reuse types in referenced assemblies" is checked.
The reason for this is that STEs contain logic which cannot be transfered by "Add service reference", so you have to share these types to have tracing logic on client as well.
After reading the following tip from Daniel Simmons, the STE starts tracking. Here is the link for the full article. http://msdn.microsoft.com/en-us/magazine/ee335715.aspx
Make certain to reuse the Self-Tracking Entity template’s generated entity code on your client. If you use proxy code generated by Add Service Reference in Visual Studio or some other tool, things look right for the most part, but you will discover that the entities don’t actually keep track of their changes on the client.
so in the client make sure you don't use add service reference to get the proxy instead access service through following code.
var svc = new ChannelFactory<IMyService>("BasicHttpBinding_IMyService").CreateChannel();
var res = svc.GetResource(1);
If you are using STEs without WCF you may have to call StartTracking() manually.
I had the same exact problem and found the solution.
It appears that for the self-tracking entities to automatically start tracking, you need to reference your STE project before adding the service reference.
This way Visual Studio generates some .datasource files which does the final trick.
I found the solution here:
http://blogs.u2u.be/diederik/post/2010/05/18/Self-Tracking-Entities-with-Validation-and-Tracking-State-Change-Notification.aspx
As for starting the tracking manually, it seems that you do not have these methods on the client-side.
Hope it helps...