If you recognize the error from the title of this post, you can jump to the solution.
The problem
I have a ASP.NET 5 solution with two projects, a web application project and a class library project.
After adding the class library I was very surprised to get this error –
The type 'IEnumerable<>' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.
All I was doing was querying an Entity Framework context for some simple data and returning the result as an IEnumerable.
This is not the code but is close enough.
var members = _context.Members.Where(m => m.FirstName.Contains(firstName));
To verify that I wasn’t messing up something very simple I tried the same code from the web api controller in the web application, it compiled and worked fine. I looked in the references for both projects for an indication that I had left something out of my class library but could find nothing.
I checked the project.json for both and messed around in nuget for a while but all looked fine.
The project.lock.json files
Finally, I had a look in the project.lock.json files and noticed this section in the web application file.
{
"locked": false,
"version": 2,
"targets": {
"DNX,Version=v4.5.1": {
"EntityFramework.Core/7.0.0-rc1-final": {
"type": "package",
"dependencies": {
"Ix-Async": "1.2.5",
"Microsoft.Extensions.Caching.Abstractions": "1.0.0-rc1-final",
"Microsoft.Extensions.Caching.Memory": "1.0.0-rc1-final",
"Microsoft.Extensions.DependencyInjection": "1.0.0-rc1-final",
"Microsoft.Extensions.DependencyInjection.Abstractions": "1.0.0-rc1-final",
"Microsoft.Extensions.Logging": "1.0.0-rc1-final",
"Microsoft.Extensions.Logging.Abstractions": "1.0.0-rc1-final",
"Microsoft.Extensions.OptionsModel": "1.0.0-rc1-final",
"Remotion.Linq": "2.0.1",
"System.Collections.Immutable": "1.1.36"
},
"frameworkAssemblies": [
"Microsoft.CSharp",
"mscorlib",
"System",
"System.Collections",
"System.ComponentModel.DataAnnotations",
"System.Core",
"System.Diagnostics.Debug",
"System.Diagnostics.Tools",
"System.Globalization",
"System.Linq",
"System.Linq.Expressions",
"System.Linq.Queryable",
"System.ObjectModel",
"System.Reflection",
"System.Reflection.Extensions",
"System.Resources.ResourceManager",
"System.Runtime",
"System.Runtime.Extensions",
"System.Threading"
],
There in the project.lock.json for the web application project is "System.Runtime" in the "frameworkAssemblies" section.
But the same section in the class library’s file did NOT have a "System.Runtime".
{
"locked": false,
"version": 2,
"targets": {
".NETFramework,Version=v4.5.1": {
"EntityFramework.Core/7.0.0-rc1-final": {
"type": "package",
"dependencies": {
"Ix-Async": "1.2.5",
"Microsoft.Extensions.Caching.Abstractions": "1.0.0-rc1-final",
"Microsoft.Extensions.Caching.Memory": "1.0.0-rc1-final",
"Microsoft.Extensions.DependencyInjection": "1.0.0-rc1-final",
"Microsoft.Extensions.DependencyInjection.Abstractions": "1.0.0-rc1-final",
"Microsoft.Extensions.Logging": "1.0.0-rc1-final",
"Microsoft.Extensions.Logging.Abstractions": "1.0.0-rc1-final",
"Microsoft.Extensions.OptionsModel": "1.0.0-rc1-final",
"Remotion.Linq": "2.0.1",
"System.Collections.Immutable": "1.1.36"
},
"frameworkAssemblies": [
"Microsoft.CSharp",
"mscorlib",
"System",
"System.ComponentModel.DataAnnotations",
"System.Core"
],
I added "System.Runtime" into the project.lock.json of class library project and everything compiled and worked.
But, and this is a big but, the project.lock.json file is generated from the project.json file and any changes to nuget or to the porject.json will lead to my project.lock.json being overwritten.
At least I know the culprit and now I had to figure out how to get that entry for "System.Runtime" to be generated and put into "frameworkAssemblies".
Note also that line 5 for the two files also differs, this I think is more telling problem.
"DNX,Version=v4.5.1": {
vs
".NETFramework,Version=v4.5.1": {
Time to compare the project.json files.
The project.json files
This is project.json in the web application project
{
"version": "1.0.0-*",
"compilationOptions": {
"emitEntryPoint": true
},
"dependencies": {
"EntityFramework.MicrosoftSqlServer": "7.0.0-rc1-final",
"Member.Business": "1.0.0-*",
"Member.DataLayer": "1.0.0-*",
"Member.Domain": "1.0.0-*",
"Microsoft.AspNet.IISPlatformHandler": "1.0.0-rc1-final",
"Microsoft.AspNet.Mvc": "6.0.0-rc1-final",
"Microsoft.AspNet.Server.Kestrel": "1.0.0-rc1-final",
"Microsoft.AspNet.StaticFiles": "1.0.0-rc1-final",
"Microsoft.CSharp": "4.0.0",
"Microsoft.Extensions.Configuration.FileProviderExtensions": "1.0.0-rc1-final",
"Microsoft.Extensions.Configuration.Json": "1.0.0-rc1-final",
"Microsoft.Extensions.Logging": "1.0.0-rc1-final",
"Microsoft.Extensions.Logging.Console": "1.0.0-rc1-final",
"Microsoft.Extensions.Logging.Debug": "1.0.0-rc1-final"
},
"commands": {
"web": "Microsoft.AspNet.Server.Kestrel"
},
"frameworks": {
"dnx451": { },
"dnxcore50": { }
},
"exclude": [
"wwwroot",
"node_modules"
],
"publishExclude": [
"**.user",
"**.vspscc"
]
}
And this is in the class library project.
{
"version": "1.0.0-*",
"description": "Member.Business Class Library",
"authors": [ "bryan" ],
"tags": [ "" ],
"projectUrl": "",
"licenseUrl": "",
"frameworks": {
"net451": { },
"dotnet5.4": {
"dependencies": {
"Microsoft.CSharp": "4.0.1-beta-23516",
"System.Collections": "4.0.11-beta-23516",
"System.Linq": "4.0.1-beta-23516",
"System.Runtime": "4.0.21-beta-23516",
"System.Threading": "4.0.11-beta-23516"
}
}
},
"dependencies": {
"EntityFramework.MicrosoftSqlServer": "7.0.0-rc1-final",
"Member.DataLayer": "1.0.0-*",
"Member.Domain": "1.0.0-*"
}
}
There are some serious differences between the two, most notably around the “frameworks” and “dependencies”. I have no idea why the two project.json files are so different.
Solution A and B
I changed my project.json in the class library project to the below adding the "frameworkAssemblies" node.
{
"version": "1.0.0-*",
"description": "Fund.FundEntitlement.Business Class Library",
"authors": [ "bryan" ],
"tags": [ "" ],
"projectUrl": "",
"licenseUrl": "",
"frameworks": {
"net451": {
"frameworkAssemblies": {
"System.Runtime": "4.0.10.0"
}
},
"dotnet5.4": {
"dependencies": {
"Microsoft.CSharp": "4.0.1-beta-23516",
"System.Collections": "4.0.11-beta-23516",
"System.Linq": "4.0.1-beta-23516",
"System.Runtime": "4.0.21-beta-23516",
"System.Threading": "4.0.11-beta-23516"
}
}
},
"dependencies": {
"EntityFramework.MicrosoftSqlServer": "7.0.0-rc1-final",
"Fund.FundEntitlement.DataLayer": "1.0.0-*",
"Fund.FundEntitlement.Domain": "1.0.0-*"
}
}
An alternative that also works is changing the project.json in the class library to look more like the on from the web application project.
{
"version": "1.0.0-*",
"description": "Fund.FundEntitlement.Business Class Library",
"authors": [ "bryan" ],
"tags": [ "" ],
"projectUrl": "",
"licenseUrl": "",
"frameworks": {
"dnx451": { },
"dnxcore50": {
"dependencies": {
"Microsoft.CSharp": "4.0.1-beta-23516"
}
}
},
"dependencies": {
"EntityFramework.MicrosoftSqlServer": "7.0.0-rc1-final",
"Fund.FundEntitlement.DataLayer": "1.0.0-*",
"Fund.FundEntitlement.Domain": "1.0.0-*",
"System.Collections": "4.0.11-beta-23516",
"System.Linq": "4.0.1-beta-23516",
"System.Runtime": "4.0.21-beta-23516",
"System.Threading": "4.0.11-beta-23516"
}
}
Now everything compiles and all is good. I’m sadly sure it won’t be the last time I have screw around with project.lock.json and project.json. For more info about those files see http://davidfowl.com/diagnosing-dependency-issues-with-asp-net-5/