The highly productive Julia web framework

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Using JSON payloads

A very common design pattern, especially when developing REST APIs, is to accept JSON payloads sent as application/json POST data. Genie efficiently handles this use case through the utility function Requests.jsonpayload. Under the cover, Genie will process the POST request and will attempt to parse the JSON text payload to a Julia Dict{String,Any}. If this fails, an error will be logged, but will not be thrown. If this happens, you can still access the raw value (the text payload not converted to JSON) by using the Requests.rawpayload method.


using Genie, Genie.Router, Genie.Requests, Genie.Renderer

route("/jsonpayload", method = POST) do
  @show jsonpayload()
  @show rawpayload()

  json("Hello $(jsonpayload()["name"])")


Next we make a POST request using the HTTP package:

using HTTP

HTTP.request("POST", "http://localhost:8000/jsonpayload", [("Content-Type", "application/json")], """{"name":"Adrian"}""")

We will get the following output:

jsonpayload() = Dict{String,Any}("name"=>"Adrian")
rawpayload() = "{\"name\":\"Adrian\"}"

INFO:Main: /jsonpayload 200

HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

"Hello Adrian""""

First, for the two @show callse, notice how jsonpayload had successfully converted the POST data to a Dict. While the rawpayload returns the POST data as a String, exactly as received. Finally, our route handler returns a JSON response, greeting the user by extracting the name from within the jsonpayload Dict.