When utilizing Entity Framework Entity Connection, a MetadataException occurs.

entity-framework

Question

This code:

using (EntityConnection conn = new EntityConnection("name=ELSCommonEntities"))
{
  conn.Open();
}

Gives me the following error:

Test method ELS.Service.Business.IntegrationTest.Base.ServiceBaseIntegrationTest.StartLoggingTestMethod threw exception:  System.Data.MetadataException: Unable to load the specified metadata resource..

With the following stack trace:

System.Data.Metadata.Edm.MetadataArtifactLoaderCompositeResource.LoadResources(String assemblyName, String resourceName, ICollection`1 uriRegistry, MetadataArtifactAssemblyResolver resolver)
System.Data.Metadata.Edm.MetadataArtifactLoaderCompositeResource.CreateResourceLoader(String path, ExtensionCheck extensionCheck, String validExtension, ICollection`1 uriRegistry, MetadataArtifactAssemblyResolver resolver)
System.Data.Metadata.Edm.MetadataArtifactLoader.Create(String path, ExtensionCheck extensionCheck, String validExtension, ICollection`1 uriRegistry, MetadataArtifactAssemblyResolver resolver)
System.Data.EntityClient.EntityConnection.SplitPaths(String paths)
System.Data.EntityClient.EntityConnection.GetMetadataWorkspace(Boolean initializeAllCollections)
System.Data.EntityClient.EntityConnection.InitializeMetadata(DbConnection newConnection, DbConnection originalConnection, Boolean closeOriginalConnectionOnFailure)
System.Data.EntityClient.EntityConnection.Open()
ELS.Service.Business.Base.ServiceBase.StartLogging(String userWindowsLogon) in C:\C-TOM\ELS-RELEASE1\ELS.Service.Business\Base\ServiceBase.cs: line 98
ELS.Service.Business.IntegrationTest.Base.ServiceBaseIntegrationTest.StartLoggingTestMethod() in C:\C-TOM\ELS-RELEASE1\ELS.Service.Business.IntegrationTest\Base\ServiceBaseIntegrationTest.cs: line 65

However, this code which uses the same connection string:

using (ELSCommonEntities db = new ELSCommonEntities())
{
    var res = from c in db.Logging
              select c;

    int i = res.Count();
}

Does not give an error.

The connection string is:

<add name="ELSCommonEntities" connectionString="metadata=res://*/Common.CommonModel.csdl|res://*/Common.CommonModel.ssdl|res://*/Common.CommonModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=localhost;Initial Catalog=els5_demo;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient" />

I have also opened up the dll in reflector and the metadata looks ok.

1
66
2/2/2017 12:46:36 AM

Accepted Answer

Found the problem.

The standard metadata string looks like this:

metadata=res://*/Model.csdl|res://*/Model.ssdl|res://*/Model.msl

And this works fine in most cases. However, in some (including mine) Entity Framework get confused and does not know which dll to look in. Therefore, change the metadata string to:

metadata=res://nameOfDll/Model.csdl|res://nameOfDll/Model.ssdl|res://nameOfDll/Model.msl

And it will work. It was this link that got me on the right track:

http://itstu.blogspot.com/2008/07/to-load-specified-metadata-resource.html

Although I had the oposite problem, did not work in unit test, but worked in service.

114
2/10/2013 9:11:52 PM

Popular Answer

I had the same error message, and the problem was also the metadata part of the connection string, but I had to dig a little deeper to solve it and wanted to share this little nugget:

The metadata string is made up of three sections that each look like this:

res://
      (assembly)/
      (model name).(ext)

Where ext is "csdl", "ssdl", and "msl".

For most people, assembly can probably be "*", which seems to indicate that all loaded assemblies will be searched (I haven't done a huge amount of testing of this). This part wasn't an issue for me, so I can't comment on whether you need the assembly name or file name (i.e., with or without ".dll"), though I have seen both suggested.

The model name part should be the name and namespace of your .edmx file, relative to your assembly. So if you have a My.DataAccess assembly and you create DataModels.edmx in a Models folder, its full name is My.DataAccess.Models.DataModels. In this case, you would have "Models.DataModels.(ext)" in your metadata.

If you ever move or rename your .edmx file, you will need to update your metadata string manually (in my experience), and remembering to change the relative namespace will save a few headaches.



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