API POST request in Julia - json

Question

I am trying to convert some Python code to Julia. Here is the Python code:
url = "http://api.scb.se/OV0104/v1/doris/sv/ssd/START/BE/BE0101/BE0101G/BefUtvKon1749"
json = {
"query": [
{
"code": "Kon",
"selection": {
"filter": "item",
"values": [
"1",
"2"
]
}
},
{
"code": "ContentsCode",
"selection": {
"filter": "item",
"values": [
"000000LV"
]
}
}
],
"response": {
"format": "px"
}
}
r = requests.post(url=url, json=json)
Below is the Julia code, that is not working, with this error message:
syntax: { } vector syntax is discontinued around path:8
top-level scope at population_data.jl:8
using DataFrames, DataFramesMeta, HTTP, JSON3
url = "http://api.scb.se/OV0104/v1/doris/sv/ssd/START/BE/BE0101/BE0101G/BefUtvKon1749"
json = {
"query": [
{
"code": "Kon",
"selection": {
"filter": "item",
"values": [
"1",
"2",
"1+2"
]
}
},
{
"code": "ContentsCode",
"selection": {
"filter": "item",
"values": [
"000000LV"
]
}
}
],
"response": {
"format": "px"
}
}
r = HTTP.post(url, json)
My attempts to solve this are the following:
Convert the json variable to a string using """ around it.
Converting the JSON string to Julia data types, using JSON3.read()
Passing the converted JSON string to the POST request. This gives the following error:
IOError(Base.IOError("read: connection reset by peer (ECONNRESET)", -54) during request(http://api.scb.se/OV0104/v1/doris/sv/ssd/START/BE/BE0101/BE0101G/BefUtvKon1749)
None of it works, and I am not even sure that it is about the JSON format. It could be that I am passing the wrong parameters to the POST request. What should I do?

Answer 1

One way of solving this consists in building the parameters as native julia data structures, and use JSON to convert and use them as the body of your PUT request:
Dictionaries in julia are built using a syntax like Dict(key => value). Arrays are built using a standard syntax: [a, b, c]. The julia native data structure equivalent to your parameters would look like this:
params = Dict(
"query" => [
Dict("code" => "Kon",
"selection" => Dict(
"filter" => "item",
"values" => [
"1",
"2",
"1+2"
]),
),
Dict("code"=> "ContentsCode",
"selection" => Dict(
"filter" => "item",
"values" => [
"000000LV"
]),
),
],
"response" => Dict(
"format" => "px"
))
Then, you can use JSON.json() to build the JSON representation of it as a string and pass it to the HTTP request:
using HTTP
using JSON
url = "http://api.scb.se/OV0104/v1/doris/sv/ssd/START/BE/BE0101/BE0101G/BefUtvKon1749"
# send the request
r = HTTP.request("POST", url,
["Content-Type" => "application/json"],
JSON.json(params))
# retrieve the response body as a string
b = String(r.body)