# Cannot assign struct as a dictionary value
**URL:** https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027
**Category:** New to Julia
**Created:** [January 27, 2021, 2:38am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027 "2021-01-27T02:38:59Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@ruysan](https://discourse.julialang.org/u/ruysan)
#### Post date: [January 27, 2021, 2:38am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027/1 "2021-01-27T02:38:59Z")
Hi!
I have a simple struct to store some data:
```julia
struct Gene
name::String
exonarray::Array
pi::Int64
pf::Int64
is_reverse::Bool
#note::String
end
```
I then get some data from a file and generate an object:
```julia
myname = "Gene_1"
myarray = []
mypi = 1
mypf = 1500
myrev = false
mygene = Gene(myname,myarray,mypi,mypf,myrev)
```
Then, I want to push this new object into a dictionary, using a string as key.
```julia
mydict = Dict
mydict[myname] = mygene
```
This raises an error:
```julia
ERROR: LoadError: MethodError: no method matching setindex!(::Type{Dict}, ::Gene, ::String)
```
What am I doing wrong? How do I assign a struct as a Dictionary value?
---
### Author:  [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)
#### Post date: [January 27, 2021, 2:50am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027/2 "2021-01-27T02:50:46Z")
> [@ruysan](#):
>
> `mydict = Dict`
Change that to `mydict = Dict()`.
Or even better:
```julia
mydict = Dict{String, Gene}()
```
---
### Author:  [@ruysan](https://discourse.julialang.org/u/ruysan)
#### Post date: [January 27, 2021, 4:50am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027/3 "2021-01-27T04:50:35Z")
if I try
```julia
mydict = Dict()
#or
mydict = Dict{String,Gene}()
```
I get a slightly different error:
```julia
ERROR: LoadError: MethodError: no method matching getindex(::Gene, ::Int64)
```
---
### Author:  [@sostock](https://discourse.julialang.org/u/sostock)
#### Post date: [January 27, 2021, 6:30am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027/4 "2021-01-27T06:30:24Z")
What code are you running to get this error? The code you posted above works with either `mydict = Dict()` or `mydict = Dict{String,Gene}()`:
```julia
julia> struct Gene
name::String
exonarray::Array
pi::Int64
pf::Int64
is_reverse::Bool
#note::String
end
julia> myname = "Gene_1"
"Gene_1"
julia> myarray = []
Any[]
julia> mypi = 1
1
julia> mypf = 1500
1500
julia> myrev = false
false
julia> mygene = Gene(myname,myarray,mypi,mypf,myrev)
Gene("Gene_1", Any[], 1, 1500, false)
julia> mydict = Dict{String,Gene}()
Dict{String,Gene}()
julia> mydict[myname] = mygene
Gene("Gene_1", Any[], 1, 1500, false)
julia> mydict
Dict{String,Gene} with 1 entry:
"Gene_1" => Gene("Gene_1", Any[], 1, 1500, false)
```
---
### Author:  [@ruysan](https://discourse.julialang.org/u/ruysan)
#### Post date: [January 27, 2021, 7:21am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027/5 "2021-01-27T07:21:36Z")
Big confusion. I modified the variable names a bit, (like my\_dict to mydict, and my\_gene to mygene).
Now the code works as it should. Thanks for your help!
What is the effect of the ()? What is the difference between Dict and Dict()?
---
### Author:  [@sostock](https://discourse.julialang.org/u/sostock)
#### Post date: [January 27, 2021, 7:48am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027/6 "2021-01-27T07:48:02Z")
`Dict` is a type and `Dict()` creates an object of that type (in this case, of the type `Dict{Any,Any}`, which is a concrete subtype of `Dict`). It’s like the difference between `Int64` (a type) and `5` (a value of that type).
---
### Author:  [@sostock](https://discourse.julialang.org/u/sostock)
#### Post date: [January 27, 2021, 7:59am UTC](https://discourse.julialang.org/t/cannot-assign-struct-as-a-dictionary-value/54027/7 "2021-01-27T07:59:10Z")
> [@ruysan](#):
>
> ```julia
> struct Gene
> name::String
> exonarray::Array
> pi::Int64
> pf::Int64
> is_reverse::Bool
> #note::String
> end
>
> ```
For better performance, you should pick a concrete type for the `exonarray` field, like `Array{Int64,1}` instead of `Array`.