Serde_json error in posting file to remote server

[sayyed-kamran]

I am using following code to post a json file to an http server (https://paste.rs/). Everything goes normal but when the json file is posted there, the contents of json file are store in reverse order. I am giving the code, the actual json file contents and the json file posted to http server.

The code used to post a Json file to http server

use error_chain::error_chain;
use serde_json:: {Value};
use std::env;
use std::fs;

error_chain! {
     foreign_links {
         HttpRequest(reqwest::Error);
         IoError(::std::io::Error);
     }
 }
 #[tokio::main]

async fn main() -> Result<()> {
    //Get file name from command line argument
    let args: Vec<String> = env::args().collect();    
    let file_name = &args[1];
    println!("The file name is: {}", file_name);

    //First load the file into a string
    let text = fs::read_to_string(file_name)?;
    println!("The text of the file is {}", text);

    //Parse the string into a dynamically-typed JSON structure.
    let json_file= serde_json::from_str::<Value>(&text).unwrap();
    

    //Post the file to an http server     
    let client = reqwest::Client::new();
    let res = client.post("https://paste.rs")
        .json(&json_file)
        .send()
        .await?;

    //Get and print responce values
     let response_text = res.text().await?;
     println!("Your paste is located at: {}",response_text );   
     Ok(())            
}

Contents of actual Json File

{
    "quiz": {
        "sport": {
            "q1": {
                "question": "Which one is correct team name in NBA?",
                "options": [
                    "New York Bulls",
                    "Los Angeles Kings",
                    "Golden State Warriros",
                    "Huston Rocket"
                ],
                "answer": "Huston Rocket"
            }
        },
        "maths": {
            "q1": {
                "question": "5 + 7 = ?",
                "options": [
                    "10",
                    "11",
                    "12",
                    "13"
                ],
                "answer": "12"
            },
            "q2": {
                "question": "12 - 8 = ?",
                "options": [
                    "1",
                    "2",
                    "3",
                    "4"
                ],
                "answer": "4"
            }
        }
    }
}

The contents of file posted to http server

{
    "quiz": {
        "maths": {
            "q1": {
                "answer": "12",
                "options": [
                    "10",
                    "11",
                    "12",
                    "13"
                ],
                "question": "5 + 7 = ?"
            },
            "q2": {
                "answer": "4",
                "options": [
                    "1",
                    "2",
                    "3",
                    "4"
                ],
                "question": "12 - 8 = ?"
            }
        },
        "sport": {
            "q1": {
                "answer": "Huston Rocket",
                "options": [
                    "New York Bulls",
                    "Los Angeles Kings",
                    "Golden State Warriros",
                    "Huston Rocket"
                ],
                "question": "Which one is correct team name in NBA?"
            }
        }
    }
}

[semicoleon]

JSON maps are unordered, you shouldn't rely on any parsing or serializing library preserving the order unless they explicitly specify that they do so^[1] .

If you're just sending the JSON data there's not really any reason to parse it though. You can just set the body data directly and manually add the content type header.

---

1. and generally caring about the order of keys in a JSON object is just asking for trouble since that's not how the standard works ↩︎