convert Arrow-flavored eltypes to Julia-flavored eltypes on copy (#98)

* convert Arrow-flavored eltypes to Julia-flavored eltypes on copy

* Update src/arraytypes/primitive.jl

Co-authored-by: Jacob Quinn <quinn.jacobd@gmail.com>

src/arraytypes/primitive.jl

@@ -32,8 +32,8 @@ Primitive(::Type{T}, b::Vector{UInt8}, v::ValidityBitmap, data::A, l, meta) wher
 
 Base.size(p::Primitive) = (p.ℓ,)
 
-function Base.copy(p::Primitive)
-    if nullcount(p) == 0
+function Base.copy(p::Primitive{T, A}) where {T, A}
+    if nullcount(p) == 0 && T === eltype(A)
         return copy(p.data)
     else
         return convert(Array, p)

test/runtests.jl

@@ -198,6 +198,16 @@ tt = Arrow.Table(io)
 u = 0x6036fcbd20664bd8a65cdfa25434513f
 @test Arrow.ArrowTypes.arrowconvert(UUID, (value=u,)) === UUID(u)
 
+# 98
+t = (a = [Nanosecond(0), Nanosecond(1)], b = [uuid4(), uuid4()], c = [missing, Nanosecond(1)])
+io = IOBuffer()
+Arrow.write(io, t)
+seekstart(io)
+tt = Arrow.Table(io)
+@test copy(tt.a) isa Vector{Nanosecond}
+@test copy(tt.b) isa Vector{UUID}
+@test copy(tt.c) isa Vector{Union{Missing,Nanosecond}}
+
 end # @testset "misc"
 
 end