Using JuliaDB/IndexedTables with Gadfly

So I'm just trying to get Gadfly to plot an IndexedTable I've produced with the JuliaDB.table function.

The IterableTables documentation claims to support JuliaDB tables as data sources and Gadfly as a sink, but I'm doing it wrong and/or it doesn't work for me

Complete example:

julia> using IterableTables, JuliaDB, Gadfly

julia> t = table(1:10, (1:10) * 3, names = (:x, :y))
Table with 10 rows, 2 columns:
x   y
──────
1   3
2   6
3   9
4   12
5   15
6   18
7   21
8   24
9   27
10  30

julia> typeof(t)
IndexedTable{StructArrays.StructArray{NamedTuple{(:x, :y),Tuple{Int64,Int64}},1,NamedTuple{(:x, :y),Tuple{Array{Int64,1},Array{Int64,1}}}}}

julia> plot(t, x=:x, y=:y, Geom.point)
ERROR: MethodError: no method matching evalmapping(::IndexedTable{StructArrays.StructArray{NamedTuple{(:x, :y),Tuple{Int64,Int64}},1,NamedTuple{(:x, :y),Tuple{Array{Int64,1},Array{Int64,1}}}}}, ::Symbol)

```Closest candidates are:
  evalmapping(::Any, ::AbstractArray) at /home/colin/.julia/packages/Gadfly/09PWZ/src/mapping.jl:185
  evalmapping(::Any, ::Function) at /home/colin/.julia/packages/Gadfly/09PWZ/src/mapping.jl:186
  evalmapping(::Any, ::Distributions.Distribution) at /home/colin/.julia/packages/Gadfly/09PWZ/src/mapping.jl:187
  ...
Stacktrace:
 [1] evalmapping!(::Dict{Symbol,Any}, ::IndexedTable{StructArrays.StructArray{NamedTuple{(:x, :y),Tuple{Int64,Int64}},1,NamedTuple{(:x, :y),Tuple{Array{Int64,1},Array{Int64,1}}}}}, ::Gadfly.Data) at /home/colin/.julia/packages/Gadfly/09PWZ/src/mapping.jl:220
 [2] #plot#65(::Base.Iterators.Pairs{Symbol,Symbol,Tuple{Symbol,Symbol},NamedTuple{(:x, :y),Tuple{Symbol,Symbol}}}, ::Function, ::IndexedTable{StructArrays.StructArray{NamedTuple{(:x, :y),Tuple{Int64,Int64}},1,NamedTuple{(:x, :y),Tuple{Array{Int64,1},Array{Int64,1}}}}}, ::Type{Gadfly.Geom.PointGeometry}) at /home/colin/.julia/packages/Gadfly/09PWZ/src/Gadfly.jl:327
 [3] (::getfield(Gadfly, Symbol("#kw##plot")))(::NamedTuple{(:x, :y),Tuple{Symbol,Symbol}}, ::typeof(plot), ::IndexedTable{StructArrays.StructArray{NamedTuple{(:x, :y),Tuple{Int64,Int64}},1,NamedTuple{(:x, :y),Tuple{Array{Int64,1},Array{Int64,1}}}}}, ::Type{Gadfly.Geom.PointGeometry}) at ./none:0
 [4] top-level scope at none:0

Reproduce the complete Julia example using IterableTables, JuliaDB, and Gadfly, then start with the evalmapping methods in Gadfly's mapping.jl named in the stack trace. Trace how plot handles the IndexedTable and verify that the example succeeds without the MethodError.