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Better error upon non-existent file #122
Description
The current error for an invalid path is not great:
julia> using GeoJSON
julia> GeoJSON.read("not/a/path.geojson.json")
┌ Warning: Failed to parse GeoJSON as 2D, trying 3D. Set `ndim` to 3 to avoid this warning.
└ @ GeoJSON C:\Users\densb\.julia\packages\GeoJSON\73eSw\src\io.jl:21
ERROR: ArgumentError: invalid JSON at byte position 1 while parsing type GeoJSON.GeoJSONT{3, Float32}: ExpectedOpeningObjectChar
not/a/path.geojson.json
Stacktrace:
[1] invalid(error::JSON3.Error, buf::Base.CodeUnits{UInt8, String}, pos::Int64, T::Type)
@ JSON3 C:\Users\densb\.julia\packages\JSON3\rT1w2\src\JSON3.jl:30
[2] #_read#57
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:836 [inlined]
[3] _read
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:755 [inlined]
[4] #read#56
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:752 [inlined]
[5] read
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:746 [inlined]
[6] #read#47
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:441 [inlined]
[7] read
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:439 [inlined]
[8] parse(str::String, ::Type{GeoJSON.GeoJSONWrapper{…} where X<:GeoJSON.GeoJSONT{…}}; jsonlines::Bool, kw::@Kwargs{})
@ JSON3 C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:40
[9] parse
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:32 [inlined]
[10] #read#18
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:46 [inlined]
[11] read(str::String, ::Type{GeoJSON.GeoJSONWrapper{3, Float32, X} where X<:GeoJSON.GeoJSONT{3, Float32}})
@ JSON3 C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:45
[12] read(io::String; lazyfc::Bool, ndim::Int64, numbertype::Type)
@ GeoJSON C:\Users\densb\.julia\packages\GeoJSON\73eSw\src\io.jl:22
[13] read(io::String)
@ GeoJSON C:\Users\densb\.julia\packages\GeoJSON\73eSw\src\io.jl:13
[14] top-level scope
@ REPL[7]:1
caused by: ArgumentError: invalid JSON at byte position 1 while parsing type GeoJSON.GeoJSONT{2, Float32}: ExpectedOpeningObjectChar
not/a/path.geojson.json
Stacktrace:
[1] invalid(error::JSON3.Error, buf::Base.CodeUnits{UInt8, String}, pos::Int64, T::Type)
@ JSON3 C:\Users\densb\.julia\packages\JSON3\rT1w2\src\JSON3.jl:30
[2] #_read#57
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:836 [inlined]
[3] _read
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:755 [inlined]
[4] #read#56
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:752 [inlined]
[5] read
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:746 [inlined]
[6] #read#47
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:441 [inlined]
[7] read
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:439 [inlined]
[8] parse(str::String, ::Type{GeoJSON.GeoJSONWrapper{…} where X<:GeoJSON.GeoJSONT{…}}; jsonlines::Bool, kw::@Kwargs{})
@ JSON3 C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:40
[9] parse
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:32 [inlined]
[10] #read#18
@ C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:46 [inlined]
[11] read(str::String, ::Type{GeoJSON.GeoJSONWrapper{2, Float32, X} where X<:GeoJSON.GeoJSONT{2, Float32}})
@ JSON3 C:\Users\densb\.julia\packages\JSON3\rT1w2\src\structs.jl:45
[12] read(io::String; lazyfc::Bool, ndim::Int64, numbertype::Type)
@ GeoJSON C:\Users\densb\.julia\packages\GeoJSON\73eSw\src\io.jl:18
[13] read(io::String)
@ GeoJSON C:\Users\densb\.julia\packages\GeoJSON\73eSw\src\io.jl:13
[14] top-level scope
@ REPL[7]:1
Some type information was truncated. Use `show(err)` to see complete types.
Now because GeoJSON.read accepts a string (I assume a json-string), then I guess the parser attempts to parse the incorrect path as a string, which is reasonable. It is just not very user-friendly.
So how about this: If there is no file at the given string (by isfile(path)) AND the parsing fails, state that the given string is not a valid path, nor parsable as the contents of a json file.
It is quite possible that this issue should be upstreamed to JSON3.jl (or JSON.jl I suppose).
Reacted by Rafael Schouten
Activity
rafaqz commentedon Jun 1, 2026
Sounds good to me!
asinghvi17 commentedon Jun 1, 2026
We still haven't switched to JSON.jl v1.0 so right now it's all JSON3.jl
asinghvi17 commentedon Jun 1, 2026
I believe JSON3 deliberately separated their APIs for this, so we should embed a try catch in GeoJSON.read probably? Try JSON parsing first, if that fails check
isfileand then runopen(file) do io; JSON3.read(io, GeoJSON....); endor so.