The type initializer f threw an exception..InnerMessage: Could not load type 'System.Web.Hosting.HostingEnvironment' from assembly

[tforkmann]

Description

I'm trying to use an app.config file to get the DataContext on runtime.

But getting following error message:

Can't get DataContext. Message: The type initializer for '<StartupCode$..>.$Config' threw an exception.. InnerMessage: Could not load type 'System.Web.Hosting.HostingEnvironment' from assembly 'System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

Repro steps

Please provide the steps required to reproduce the problem

1. Adding CompileTime ConnectionString let [<Literal>] CompileTimeConnectionString = "Data Source=...."

2. Get SqlType: type Sql = SqlDataProvider<Common.DatabaseProviderTypes.MSSQLSERVER, ConnectionString=CompileTimeConnectionString,UseOptionTypes=true, ContextSchemaPath = ContextSchemaPath>

3. Add RunTime ConnectionString to App.Config file:

   <connectionStrings>
   <add name="Db"  providerName = "System.Data.ProviderName" connectionString="Server=..."/>
   </connectionStrings>

4. Use FSharp.Configuration to receive ConnectionString from the App.Config

   type Settings = AppSettings<"app.config">
   open System.Configuration
   let connectionString = Settings.ConnectionStrings.Db

5. Try to get DataContext with RunTimeConnection String let getDb () = SqlDme.GetDataContext connectionString

Expected behavior

Get GetDataContext without issues

Actual behavior

Assembly File Missing Error

Known workarounds

None

Related information

• MS SQL
• Win 10
• netCoreapp2.2

[Thorium]

I don't think this is an issue with SQLProvider.

If you do Sql.GetDataContext connectionString where the connectionString is a string it should work?

So you are just missing an assembly reference to e.g. System.Web or System.Web.Hosting when using something in there in your project. SQLProvider doesn't use System.Web at all, but maybe the configuration typeprovider does.

[tforkmann]

Yes, if the connection String is a string. The typeprovider works like a charm!

Ok, I guess this is related to the configuration typeprovider.

[tforkmann]

Ok, I got rid of the configuration typeprovider and used the standard System.Configuration module instead and it just works.