Merge pull request jqnatividad#1031 from jqnatividad/rename-all_generic

`rename`: add `"_all generic"` special value for headers

src/cmd/rename.rs

@@ -1,12 +1,20 @@
 static USAGE: &str = r#"
-Rename the columns of CSV data efficiently.
+Rename the columns of a CSV efficiently.
 
-This command lets you rename the columns in CSV data. You must specify
-all of the headers, and separate them by a comma.
+This command lets you rename the columns in a CSV. The new column names
+are given as a comma-separated list of names. The number of column names
+given must match the number of columns in the CSV unless "_all_generic"
+is used.
 
   Change the name of the columns:
   $ qsv rename id,name,title
 
+  Replace the headers with generic column names:
+    $ qsv rename _all_generic
+
+  Add generic column names to a CSV with no headers:
+    $ qsv rename _all_generic --no-headers
+
   Use column names that contains commas and conflict with the separator:
   $ qsv rename '"Date - Opening","Date - Actual Closing"'
 
@@ -16,6 +24,13 @@ Usage:
     qsv rename [options] [--] <headers> [<input>]
     qsv rename --help
 
+rename arguments:
+    <headers>              The new headers to use for the CSV.
+                           Separate multiple headers with a comma.
+                           If "_all_generic" is given, the headers will be renamed
+                           to generic column names, where the column name uses
+                           the format "_col_N" where N is the 1-based column index.
+
 Common options:
     -h, --help             Display this message
     -o, --output <file>    Write output to <file> instead of stdout.
@@ -41,7 +56,7 @@ struct Args {
 }
 
 pub fn run(argv: &[&str]) -> CliResult<()> {
-    let args: Args = util::get_args(USAGE, argv)?;
+    let mut args: Args = util::get_args(USAGE, argv)?;
 
     let rconfig = Config::new(&args.arg_input)
         .delimiter(args.flag_delimiter)
@@ -51,6 +66,16 @@ pub fn run(argv: &[&str]) -> CliResult<()> {
     let mut wtr = Config::new(&args.flag_output).writer()?;
     let headers = rdr.byte_headers()?;
 
+    if args.arg_headers.to_lowercase() == "_all_generic" {
+        let mut generic_headers = String::new();
+        for (i, _) in headers.iter().enumerate() {
+            generic_headers.push_str(&format!("_col_{},", i + 1));
+        }
+        // remove the trailing comma
+        generic_headers.pop();
+        args.arg_headers = generic_headers;
+    }
+
     let mut new_rdr = csv::Reader::from_reader(args.arg_headers.as_bytes());
     let new_headers = new_rdr.byte_headers()?;
 

tests/test_rename.rs

@@ -26,6 +26,32 @@ fn rename() {
     assert_eq!(got, expected);
 }
 
+#[test]
+fn rename_generic() {
+    let wrk = Workdir::new("rename");
+    wrk.create(
+        "in.csv",
+        vec![
+            svec!["R", "S"],
+            svec!["1", "b"],
+            svec!["2", "a"],
+            svec!["3", "d"],
+        ],
+    );
+
+    let mut cmd = wrk.command("rename");
+    cmd.arg("_all_generic").arg("in.csv");
+
+    let got: Vec<Vec<String>> = wrk.read_stdout(&mut cmd);
+    let expected = vec![
+        svec!["_col_1", "_col_2"],
+        svec!["1", "b"],
+        svec!["2", "a"],
+        svec!["3", "d"],
+    ];
+    assert_eq!(got, expected);
+}
+
 #[test]
 fn rename_noheaders() {
     let wrk = Workdir::new("rename_noheaders");
@@ -46,3 +72,24 @@ fn rename_noheaders() {
     ];
     assert_eq!(got, expected);
 }
+
+#[test]
+fn rename_noheaders_generic() {
+    let wrk = Workdir::new("rename_noheaders");
+    wrk.create(
+        "in.csv",
+        vec![svec!["1", "b"], svec!["2", "a"], svec!["3", "d"]],
+    );
+
+    let mut cmd = wrk.command("rename");
+    cmd.arg("_ALL_Generic").arg("--no-headers").arg("in.csv");
+
+    let got: Vec<Vec<String>> = wrk.read_stdout(&mut cmd);
+    let expected = vec![
+        svec!["_col_1", "_col_2"],
+        svec!["1", "b"],
+        svec!["2", "a"],
+        svec!["3", "d"],
+    ];
+    assert_eq!(got, expected);
+}