Type must be either an ITableEntity or an F# record type

[jackfoxy]

This may be as simple as a binding redirect issue, but not sure how to resolve it. I think both the successful and unsuccessful cases load the same mscorlib.dll:

Occurring in a Class library (.NET 4.6, F# 4.0) with public function on the following statement:

DigitallyCreated.FSharp.Azure.TableStorage.Query.all<QueryInternal>

QueryInternal defined thus:

type QueryInternal =
    { 
    [<PartitionKey>]QueryHash : string
    [<RowKey>] RowKey : string
    IsActive : bool
    Name : string
    Query : string
    ConnectionName : string
    CreateTime : DateTime
    }

I tried making QueryInternal public, but to no effect.

Console app ().NET 4.6, F# 4.0) calls this function and succeeds.

Class test library (.NET 4.6, F# 4.0, xUnit 1.9.2) calls this function and fails:

System.Exception was unhandled by user code Message: An exception of type 'System.Exception' occurred in mscorlib.dll but was not handled in user code Additional information: Type QueryInternal must be either an ITableEntity or an F# record type

My working theory is this is an incompatability with xUnit 1.9.2.

[daniel-chambers]

Ah, F# 4 and .NET 4.6.

I'm planning on building a new dev image on Windows 10 and VS2015 probably this week once Windows 10 lands. Once it's up and going, I'll try to reproduce this using all the new bits.

[jackfoxy]

Here is the call stack within TableStorage in the failing case:

DigitallyCreated.FSharp.Azure.dll!DigitallyCreated.FSharp.Azure.TableStorage.-cctor@159-4.Invoke(Microsoft.FSharp.Core.Unit unitVar) Line 174 DigitallyCreated.FSharp.Azure.dll!DigitallyCreated.FSharp.Azure.TableStorage.EntityQuery.get_Zero() Line 194 DigitallyCreated.FSharp.Azure.dll!DigitallyCreated.FSharp.Azure.TableStorage.Query.all() Line 335

it is failing from the match pattern t when typeof<ITableEntity>.IsAssignableFrom t

In the succeeding case it is matching the pattern t when isRecordType t in the following match statement

match typeof<'T> with
| t when typeof<ITableEntity>.IsAssignableFrom t -> 
    t.GetProperties()
    |> Seq.choose getTableEntityProperty
    |> Set.ofSeq
| t when isRecordType t -> 
    RecordTableEntityWrapper<'T>.RecordFields 
    |> Seq.map (fun p -> p.Name) 
    |> Set.ofSeq
| t -> failwithf "Type %s must be either an ITableEntity or an F# record type" t.Name

BTW, my colleague, Cameron Taggart, has a nice system called SourceLink, http://ctaggart.github.io/SourceLink/index.html, which makes debugging .NET OSS muck simpler. Making FSharp.Azure compatible would make it far simpler for people to identify issues.

[jackfoxy]

Closing. I don't know how Visual Studio ever emitted this stack trace for the error thrown. Finally discovered it was no longer emitting this stack trace. Not a problem.

[daniel-chambers]

Out of interest, what did the actual problem end up being?

[jackfoxy]

forgetting unit at the end of ToString, i.e. .ToString instead of .ToString()

[jackfoxy]

I've noticed the VS debugger leaves some Exceptin artifacts lying around. This may have been an instance of that