Generate CSV with the correct escaping.

src/pricehist/cli.py

@@ -97,6 +97,13 @@ def build_parser():
     def today():
         return datetime.now().date().isoformat()
 
+    def valid_char(s):
+        if len(s) == 1:
+            return s
+        else:
+            msg = f"Not a single character: '{s}'."
+            raise argparse.ArgumentTypeError(msg)
+
     def formatter(prog):
         return argparse.HelpFormatter(prog, max_help_position=50)
 
@@ -165,6 +172,7 @@ def build_parser():
             "[--fmt-base SYM] [--fmt-quote SYM] [--fmt-time TIME] "
             "[--fmt-decimal CHAR] [--fmt-thousands CHAR] "
             "[--fmt-symbol rightspace|right|leftspace|left] [--fmt-datesep CHAR] "
+            "[--fmt-csvdelim CHAR]"
         ),
         formatter_class=formatter,
     )
@@ -299,5 +307,12 @@ def build_parser():
         type=str,
         help=f"date separator in output (default: '{default_fmt.datesep}')",
     )
+    fetch_parser.add_argument(
+        "--fmt-csvdelim",
+        dest="formatcsvdelim",
+        metavar="CHAR",
+        type=valid_char,
+        help=f"field delimiter for CSV output (default: '{default_fmt.csvdelim}')",
+    )
 
     return parser

src/pricehist/format.py

@@ -10,6 +10,7 @@ class Format:
     thousands: str = ""
     symbol: str = "rightspace"
     datesep: str = "-"
+    csvdelim: str = ","
 
     @classmethod
     def fromargs(cls, args):
@@ -25,6 +26,7 @@ class Format:
             thousands=if_not_none(args.formatthousands, default.thousands),
             symbol=if_not_none(args.formatsymbol, default.symbol),
             datesep=if_not_none(args.formatdatesep, default.datesep),
+            csvdelim=if_not_none(args.formatcsvdelim, default.csvdelim),
         )
 
     def format_date(self, date):

src/pricehist/outputs/csv.py

@@ -1,16 +1,32 @@
-from pricehist.format import Format
+import csv
+import io
 
+from pricehist.format import Format
 from .baseoutput import BaseOutput
 
 
 class CSV(BaseOutput):
     def format(self, series, source=None, fmt=Format()):
-        lines = ["date,base,quote,amount,source,type"]
-        for price in series.prices:
-            date = fmt.format_date(price.date)
+        output = io.StringIO()
+        writer = csv.writer(
+            output,
+            delimiter=fmt.csvdelim,
+            lineterminator="\n",
+            quotechar='"',
+            doublequote=True,
+            skipinitialspace=False,
+            quoting=csv.QUOTE_MINIMAL,
+        )
+
+        header = ["date", "base", "quote", "amount", "source", "type"]
+        writer.writerow(header)
+
         base = fmt.base or series.base
         quote = fmt.quote or series.quote
+
+        for price in series.prices:
+            date = fmt.format_date(price.date)
             amount = fmt.format_num(price.amount)
-            line = ",".join([date, base, quote, amount, source.id(), series.type])
-            lines.append(line)
-        return "\n".join(lines) + "\n"
+            writer.writerow([date, base, quote, amount, source.id(), series.type])
+
+        return output.getvalue()