nushell/src/commands/to_csv.rs

use crate::object::{Primitive, Value};
use crate::prelude::*;
use log::debug;
use csv::WriterBuilder;

pub fn value_to_csv_value(v: &Value) -> Value {

    debug!("value_to_csv_value(Value::Object(v)) where v = {:?}", v);

    match v {
        Value::Primitive(Primitive::String(s)) => Value::Primitive(Primitive::String(s.clone())),
        Value::Primitive(Primitive::Nothing) => Value::Primitive(Primitive::Nothing),
        Value::Object(o) => Value::Object(o.clone()),
        Value::List(l) => Value::List(l.clone()),
        Value::Block(_) => Value::Primitive(Primitive::Nothing),
        _ => Value::Primitive(Primitive::Nothing)
    }
}

pub fn to_string(v: &Value) -> Result<String, Box<dyn std::error::Error>> {
    match v {
        Value::List(_l) => return Ok(String::from("[list list]")),
        Value::Object(o) => {

            debug!("to_csv:to_string(Value::Object(v)) where v = {:?}", v);

            let mut wtr = WriterBuilder::new().from_writer(vec![]);
            let mut fields: VecDeque<String> = VecDeque::new();
            let mut values: VecDeque<String> = VecDeque::new();

            for (k, v) in o.entries.iter() {
                fields.push_back(k.clone());
                values.push_back(to_string(&v)?);
            }
            
            wtr.write_record(fields).expect("can not write.");
            wtr.write_record(values).expect("can not write.");

            return Ok(String::from_utf8(wtr.into_inner()?)?)
        },
        Value::Primitive(Primitive::String(s)) => return Ok(s.to_string()),
        _ => return Err("Bad input".into())
    }
}

pub fn to_csv(args: CommandArgs) -> Result<OutputStream, ShellError> {
    let out = args.input;
    let name_span = args.call_info.name_span;
    Ok(out
        .values
        .map(
            move |a| match to_string(&value_to_csv_value(&a.item)) {

                Ok(x) => { 
                     ReturnSuccess::value(Value::Primitive(Primitive::String(x)).spanned(name_span))
                }
                Err(_) => Err(ShellError::maybe_labeled_error(
                    "Can not convert to CSV string",
                    "can not convert piped data to CSV string",
                    name_span,
                )),
            },
        )
        .to_output_stream())
}