Add --no-auto-unsparsify flag

pkg/cli/option_parse.go

@@ -2392,6 +2392,15 @@ var CSVTSVOnlyFlagSection = FlagSection{
 			},
 		},
 
+		{
+			name:     "--no-auto-unsparsify",
+			help:     "For CSV/TSV output: if the record keys change from one row to another, emit a blank line and a new header line. This is non-compliant with RFC 4180 but it helpful for heterogeneous data.",
+			parser: func(args []string, argc int, pargi *int, options *TOptions) {
+				options.WriterOptions.NoAutoUnsparsify = true
+				*pargi += 1
+			},
+		},
+
 		{
 			name:     "--implicit-csv-header",
 			altNames: []string{"--headerless-csv-input", "--hi", "--implicit-tsv-header"},

pkg/cli/option_types.go

@@ -134,6 +134,40 @@ type TWriterOptions struct {
 	// (all but JSON) -- unless the user explicitly asks to suppress that.
 	AutoFlatten bool
 
+	// Default CSV/TSV:
+	//   a=1,b=2,c=3
+	//   a=4,b=5
+	// leads to
+	//   a,b,c
+	//   1 2,3
+	//   4,5, <-- note trailing empty field
+	// and
+	//   a=1,b=2,c=3
+	//   d=4,e=5
+	// leads to
+	//   fatal error
+	//
+	// With this flag:
+	//   a=1,b=2,c=3
+	//   a=4,b=5
+	// leads to
+	//   a,b,c
+	//   1 2,3
+	//
+	//   a,b
+	//   4,5
+	//
+	// and
+	//   a=1,b=2,c=3
+	//   d=4,e=5
+	// leads to
+	//   a,b,c
+	//   1,2,3
+	//
+	//   d,e
+	//   4,5
+	NoAutoUnsparsify bool
+
 	// For floating-point numbers: "" means use the Go default.
 	FPOFMT string
 

pkg/output/record_writer_csv.go

@@ -46,8 +46,8 @@ func (writer *RecordWriterCSV) Write(
 	bufferedOutputStream *bufio.Writer,
 	outputIsStdout bool,
 ) error {
-	// End of record stream: nothing special for this output format
 	if outrec == nil {
+		// End of record stream: nothing special for this output format
 		return nil
 	}
 

pkg/output/record_writer_csvlite.go

@@ -32,8 +32,8 @@ func (writer *RecordWriterCSVLite) Write(
 	bufferedOutputStream *bufio.Writer,
 	outputIsStdout bool,
 ) error {
-	// End of record stream: nothing special for this output format
 	if outrec == nil {
+		// End of record stream: nothing special for this output format
 		return nil
 	}
 

pkg/output/record_writer_dkvp.go

@@ -25,8 +25,8 @@ func (writer *RecordWriterDKVP) Write(
 	bufferedOutputStream *bufio.Writer,
 	outputIsStdout bool,
 ) error {
-	// End of record stream: nothing special for this output format
 	if outrec == nil {
+		// End of record stream: nothing special for this output format
 		return nil
 	}
 

pkg/output/record_writer_nidx.go

@@ -24,8 +24,8 @@ func (writer *RecordWriterNIDX) Write(
 	bufferedOutputStream *bufio.Writer,
 	outputIsStdout bool,
 ) error {
-	// End of record stream: nothing special for this output format
 	if outrec == nil {
+		// End of record stream: nothing special for this output format
 		return nil
 	}
 

pkg/output/record_writer_tsv.go

@@ -40,8 +40,8 @@ func (writer *RecordWriterTSV) Write(
 	bufferedOutputStream *bufio.Writer,
 	outputIsStdout bool,
 ) error {
-	// End of record stream: nothing special for this output format
 	if outrec == nil {
+		// End of record stream: nothing special for this output format
 		return nil
 	}
 

pkg/output/record_writer_xtab.go

@@ -48,8 +48,8 @@ func (writer *RecordWriterXTAB) Write(
 	bufferedOutputStream *bufio.Writer,
 	outputIsStdout bool,
 ) error {
-	// End of record stream: nothing special for this output format
 	if outrec == nil {
+		// End of record stream: nothing special for this output format
 		return nil
 	}