# BSON unable to load struct with array of subtypes

**URL:** <https://discourse.julialang.org/t/bson-unable-to-load-struct-with-array-of-subtypes/33483>\
**Category:** General Usage\
**Created:** [January 17, 2020, 11:25am UTC](https://discourse.julialang.org/t/bson-unable-to-load-struct-with-array-of-subtypes/33483 "2020-01-17T11:25:11Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![HenriDeh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/henrideh/32/8316_2.png) [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Post date:** [January 17, 2020, 11:25am UTC](https://discourse.julialang.org/t/bson-unable-to-load-struct-with-array-of-subtypes/33483/1 "2020-01-17T11:25:11Z")

</div>

Am I coding wrong or should I open an issue ?  
BSON cannot load an struct that has an array of a subtype field.

```julia
julia> using BSON
julia> mutable struct Bar
       arrreal::Array{<:Real,1}
       end

julia> bar = Bar(Real[])
Bar(Real[])

julia> BSON.@save "bar.bson" bar

julia> BSON.@load "bar.bson"
ERROR: MethodError: no method matching Array{#s277,1} where #s277<:Real(::Array{Any,1})
Stacktrace:
 [1] convert(::Type{Array{#s277,1} where #s277<:Real}, ::Array{Any,1}) at .\array.jl:490
 [2] newstruct!(::Bar, ::Array{Any,1}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\extensions.jl:98
 [3] newstruct_raw(::IdDict{Any,Any}, ::Type, ::Dict{Symbol,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\extensions.jl:125
 [4] (::BSON.var"#45#46")(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\extensions.jl:140
 [5] raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:88
 [6] (::BSON.var"#20#22"{IdDict{Any,Any}})(::Dict{Symbol,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:82
 [7] applychildren!(::BSON.var"#20#22"{IdDict{Any,Any}}, ::Dict{Symbol,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\BSON.jl:21
 [8] _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:82
 [9] raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:89
 [10] raise_recursive at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:99 [inlined]
 [11] load(::String) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:104
 [12] top-level scope at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\BSON.jl:52

```

It does not happen if I instanciate with an array of concrete type.

```julia
julia> bar = Bar(Int[])
Bar(Int64[])

julia> BSON.@save "bar.bson" bar

julia> BSON.@load "bar.bson"

```

It also happens when the array is not empty.

```julia
julia> bar = Bar(Real[1, 1.0])
Bar(Real[1, 1.0])

julia> BSON.@save "bar.bson" bar

julia> BSON.@load "bar.bson"
ERROR: MethodError: no method matching Array{#s277,1} where #s277<:Real(::Array{Any,1})
Stacktrace:
 [1] convert(::Type{Array{#s277,1} where #s277<:Real}, ::Array{Any,1}) at .\array.jl:490
 [2] newstruct!(::Bar, ::Array{Any,1}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\extensions.jl:98
 [3] newstruct_raw(::IdDict{Any,Any}, ::Type, ::Dict{Symbol,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\extensions.jl:125
 [4] (::BSON.var"#45#46")(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\extensions.jl:140
 [5] raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:88
 [6] (::BSON.var"#20#22"{IdDict{Any,Any}})(::Dict{Symbol,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:82
 [7] applychildren!(::BSON.var"#20#22"{IdDict{Any,Any}}, ::Dict{Symbol,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\BSON.jl:21
 [8] _raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:82
 [9] raise_recursive(::Dict{Symbol,Any}, ::IdDict{Any,Any}) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:89
 [10] raise_recursive at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:99 [inlined]
 [11] load(::String) at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\read.jl:104
 [12] top-level scope at C:\Users\Henri\.julia\packages\BSON\Ryxwc\src\BSON.jl:52

```

I don’t think using `Array{<:Real,1}` would pose problem for anything else. I guess using a parametric type would solve the problem but that is somewhat annoying to do in my actual use case.