Make it so.

Author: semperos

.gitignore

@@ -0,0 +1,4 @@
+/target/
+**/*.rs.bk
+Cargo.lock
+.idea/

Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "csver"
+version = "0.1.0"
+license = "MIT OR Apache-2.0"
+authors = ["Daniel Gregoire <daniel.l.gregoire@gmail.com>"]
+
+[lib]
+name="csver"
+path="src/lib.rs"
+
+[[bin]]
+name="csver"
+path="src/main.rs"
+
+[dependencies]
+clap = "~2.26"
+csv = "1.0.0-beta.4"
+serde_json = "~1.0"

README.md

@@ -0,0 +1,23 @@
+# CSVer
+
+CSV utilities at the CLI.
+
+- Convert JSON array over STDIN to CSV over STDOUT
+- Specify CSV field/column delimiter
+
+## License
+
+Copyright © 2017 Daniel Gregoire.
+
+Licensed under either of
+
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any
+additional terms or conditions.

src/lib.rs

@@ -0,0 +1,67 @@
+extern crate csv;
+extern crate serde_json;
+
+use std::io;
+use std::process;
+use serde_json::value::Value;
+
+pub fn json_to_csv(stdin: &str, csv_delimiter: u8) -> io::Result<()> {
+ let mut is_array_of_objects = false;
+ let mut wtr = csv::WriterBuilder::new()
+ .delimiter(csv_delimiter)
+ .from_writer(io::stdout());
+ if let Ok(json) = serde_json::from_str::<Value>(stdin) {
+ if let Some(entries) = json.as_array() {
+ if let Some(example) = entries.first() {
+ if let Some(example_object) = example.as_object() {
+ let ks = example_object.keys();
+ // WRITE THE HEADER using example
+ wtr.write_record(ks)?;
+ wtr.flush()?;
+ is_array_of_objects = true;
+ } else {
+ eprintln!("Expected a JSON array of objects. Got: {}", json);
+ process::exit(1);
+ }
+ } else {
+ eprintln!("Will not write empty CSV, got empty JSON array.");
+ process::exit(1);
+ }
+
+ // RECORDS
+ if is_array_of_objects {
+ for entry in entries {
+ let o = entry.as_object().unwrap();
+ let vals = o.values().map(|x: &Value| match *x {
+ Value::Null => "null".to_owned(),
+ Value::Bool(ref b) => format!("{}", b),
+ Value::Number(ref n) => format!("{}", n),
+ Value::String(ref s) => s.to_owned(),
+ Value::Array(ref a) => {
+ eprintln!("Nested arrays not supported. Found {:?}", a);
+ process::exit(1);
+ }
+ Value::Object(ref o) => {
+ eprintln!("Nested objects not supported. Found {:?}", o);
+ process::exit(1);
+ }
+ });
+ wtr.write_record(vals)?;
+ }
+ }
+ } else {
+ eprintln!("Expected a JSON array of objects. Got: {}", json);
+ process::exit(1);
+ }
+ } else {
+ eprintln!("Non-JSON found: {}", stdin);
+ process::exit(1);
+ }
+ Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+ #[test]
+ fn it_works() {}
+}

src/main.rs

@@ -0,0 +1,53 @@
+extern crate clap;
+extern crate csver;
+
+use clap::{App, Arg};
+use std::io::{self, Read};
+use std::process;
+
+fn main() {
+ let matches = App::new("csver")
+ .version("0.1.0")
+ .author("Daniel Gregoire <daniel.l.gregoire@gmail.com>")
+ .about("JSON array over STDIN --> CSV over STDOUT")
+ .arg(
+ Arg::with_name("delimiter")
+ .value_name("DELIMITER")
+ .help("CSV delimiter to use between fields in each entry.")
+ .default_value("comma")
+ .long("delimiter")
+ .short("d")
+ .possible_values(&["comma", "tab"])
+ .takes_value(true),
+ )
+ .get_matches();
+
+ let delimiter_arg = matches.value_of("delimiter").unwrap().to_lowercase();
+ let delimiter = match delimiter_arg.as_ref() {
+ "comma" => b",",
+ "tab" => b"\t",
+ _ => {
+ eprintln!("Unsupported CSV delimiter. Only 'comma' or 'tab' allowed.");
+ process::exit(1);
+ }
+ };
+ println!(
+ "Delimiter arg was {} and final is {:?}",
+ delimiter_arg,
+ delimiter
+ );
+
+ let stdin = io::stdin();
+ let mut buffer = String::new();
+ stdin.lock().read_to_string(&mut buffer).expect(
+ "Couldn't read from STDIN",
+ );
+ // TODO Figure out case when nothing comes in over stdin. Tools like grep just hang.
+ if buffer.is_empty() {
+ println!("{}", matches.usage());
+ process::exit(1);
+ } else if let Err(e) = csver::json_to_csv(&buffer, delimiter[0]) {
+ eprintln!("Error converting JSON array to CSV: {:?}", e);
+ process::exit(1);
+ }
+}