cvs: Add more from/to options

Add header option, on by default
Disable comments by default
Rename comma to delimiter
Add quote_char option
Add skip initial space option

Uses a forked version of std csv to support custom quote character

See top of csv.go for TODOs

Author: wader

format/csv/csv.go

@@ -1,14 +1,26 @@
 package csv
 
+// TODO: error, throw error always? no decode value with gap etc? -d csv from_csv
+// TODO: header row field count mismatch error, csv reader takes care of check atm. can use FieldsPerRecord -1
+// TODO: row object keys mismatch writer
+// TODO: lazy quotes?
+// TODO: comment in writer? string elements?
+// TODO: to_csv objects
+// TODO: to_csv opts help
+// TODO: go maps are random order, now sorts headers
+// TODO: option aliases?
+// TODO: snake_case option?
+
 import (
 	"bytes"
 	"embed"
-	"encoding/csv"
 	"errors"
 	"fmt"
 	"io"
+	"sort"
 
 	"github.com/wader/fq/format"
+	"github.com/wader/fq/internal/csvex"
 	"github.com/wader/fq/internal/gojqex"
 	"github.com/wader/fq/pkg/bitio"
 	"github.com/wader/fq/pkg/decode"
@@ -28,8 +40,11 @@ func init() {
 			ProbeOrder:  format.ProbeOrderTextFuzzy,
 			DecodeFn:    decodeCSV,
 			DefaultInArg: format.CSV_In{
-				Comma:   ",",
-				Comment: "#",
+				Delimiter:        ",",
+				Comment:          "",
+				QuoteChar:        `"`,
+				Header:           true,
+				SkipInitialSpace: false,
 			},
 			Functions: []string{"_todisplay"},
 		})
@@ -41,29 +56,59 @@ func decodeCSV(d *decode.D) any {
 	var ci format.CSV_In
 	d.ArgAs(&ci)
 
-	var rvs []any
 	br := d.RawLen(d.Len())
-	r := csv.NewReader(bitio.NewIOReader(br))
-	r.TrimLeadingSpace = true
+	r := csvex.NewReader(bitio.NewIOReader(br))
 	r.LazyQuotes = true
-	if ci.Comma != "" {
+	if ci.Delimiter != "" {
+		r.Comma = rune(ci.Delimiter[0])
+	} else if ci.Comma != "" {
 		r.Comma = rune(ci.Comma[0])
 	}
 	if ci.Comment != "" {
 		r.Comment = rune(ci.Comment[0])
+	} else {
+		r.Comment = 0
+	}
+	if ci.QuoteChar != "" {
+		r.Quote = rune(ci.QuoteChar[0])
+	} else {
+		r.Quote = '"'
 	}
+	r.TrimLeadingSpace = ci.SkipInitialSpace
+
+	row := 1
+	var rvs []any
+
+	var headers []string
 	for {
 		r, err := r.Read()
 		if errors.Is(err, io.EOF) {
 			break
 		} else if err != nil {
 			return err
 		}
-		var vs []any
-		for _, s := range r {
-			vs = append(vs, s)
+
+		if ci.Header {
+			if headers == nil {
+				// TODO: duplicate headers?
+				headers = append(headers, r...)
+			} else {
+				obj := map[string]any{}
+				for i, s := range r {
+					h := headers[i]
+					obj[h] = s
+				}
+				rvs = append(rvs, obj)
+			}
+		} else {
+			var vs []any
+			for _, s := range r {
+				vs = append(vs, s)
+			}
+			rvs = append(rvs, vs)
 		}
-		rvs = append(rvs, vs)
+
+		row++
 	}
 
 	d.Value.V = &scalar.Any{Actual: rvs}
@@ -73,35 +118,108 @@ func decodeCSV(d *decode.D) any {
 }
 
 type ToCSVOpts struct {
-	Comma string
+	Comma     string // alias for Delimiter
+	Delimiter string
+	QuoteChar string
+	Header    bool
 }
 
 func toCSV(_ *interp.Interp, c []any, opts ToCSVOpts) any {
 	b := &bytes.Buffer{}
-	w := csv.NewWriter(b)
-	if opts.Comma != "" {
+	w := csvex.NewWriter(b)
+	if opts.Delimiter != "" {
+		w.Comma = rune(opts.Delimiter[0])
+	} else if opts.Comma != "" {
 		w.Comma = rune(opts.Comma[0])
 	}
+	if opts.QuoteChar != "" {
+		w.Quote = rune(opts.QuoteChar[0])
+	} else {
+		w.Quote = '"'
+	}
+
+	seenObject := 0
+	seenArrays := 0
+	var headers []string
+
 	for _, row := range c {
-		rs, ok := gojqex.Cast[[]any](row)
-		if !ok {
-			return fmt.Errorf("expected row to be an array, got %s", gojqex.TypeErrorPreview(row))
-		}
-		vs, ok := gojqex.NormalizeToStrings(rs).([]any)
-		if !ok {
-			panic("not array")
-		}
-		var ss []string
-		for _, v := range vs {
-			s, ok := v.(string)
+		switch row.(type) {
+		case []any:
+			if seenObject > 0 {
+				return fmt.Errorf("mixed row types, expected row to be an object, got %s", gojqex.TypeErrorPreview(row))
+			}
+
+			rs, ok := gojqex.Cast[[]any](row)
 			if !ok {
-				return fmt.Errorf("expected row record to be scalars, got %s", gojqex.TypeErrorPreview(v))
+				return fmt.Errorf("expected row to be an array, got %s", gojqex.TypeErrorPreview(row))
 			}
-			ss = append(ss, s)
-		}
-		if err := w.Write(ss); err != nil {
-			return err
+			vs, ok := gojqex.NormalizeToStrings(rs).([]any)
+			if !ok {
+				panic("not array")
+			}
+			var ss []string
+			for _, v := range vs {
+				s, ok := v.(string)
+				if !ok {
+					return fmt.Errorf("expected row record to be scalars, got %s", gojqex.TypeErrorPreview(v))
+				}
+				ss = append(ss, s)
+			}
+			if err := w.Write(ss); err != nil {
+				return err
+			}
+
+			seenArrays++
+		case map[string]any:
+			if seenArrays > 0 {
+				return fmt.Errorf("mixed row types, expected row to be an array, got %s", gojqex.TypeErrorPreview(row))
+			}
+
+			rm, ok := gojqex.Cast[map[string]any](row)
+			if !ok {
+				return fmt.Errorf("expected row to be an object, got %s", gojqex.TypeErrorPreview(row))
+			}
+			vm, ok := gojqex.NormalizeToStrings(rm).(map[string]any)
+			if !ok {
+				panic("not object")
+			}
+
+			if headers == nil {
+				// TODO: maps are random order in go
+				for k := range vm {
+					headers = append(headers, k)
+				}
+				sort.Strings(headers)
+
+				if err := w.Write(headers); err != nil {
+					return err
+				}
+			}
+
+			var ss []string
+			keysFound := 0
+			for _, k := range headers {
+				s, ok := vm[k].(string)
+				if !ok {
+					return fmt.Errorf("expected row object to have a %q key, %s", k, gojqex.TypeErrorPreview(row))
+				}
+				ss = append(ss, s)
+				keysFound++
+			}
+			// TODO: what keys are extra/missing
+			if keysFound < len(headers) {
+				return fmt.Errorf("expected row object has missing keys %s", gojqex.TypeErrorPreview(row))
+			} else if keysFound > len(headers) {
+				return fmt.Errorf("expected row object has extra keys %s", gojqex.TypeErrorPreview(row))
+			}
+
+			if err := w.Write(ss); err != nil {
+				return err
+			}
+
+			seenObject++
 		}
+
 	}
 	w.Flush()
 

format/format.go

@@ -363,8 +363,12 @@ type HTML_In struct {
 }
 
 type CSV_In struct {
-	Comma   string `doc:"Separator character"`
-	Comment string `doc:"Comment line character"`
+	Comma            string `doc:"Alias for Delimiter"`
+	Delimiter        string `doc:"Field delimiter character"`
+	Comment          string `doc:"Comment line character"`
+	QuoteChar        string `doc:"Quote character"`
+	Header           bool   `doc:"Convert to objects based on header"`
+	SkipInitialSpace bool   `doc:"Don't include leading whitespace"`
 }
 
 type Bitcoin_Block_In struct {

internal/csvex/README.md

@@ -0,0 +1 @@
+Modified version of go std encoding/csv Reader/Writer to support difference quote character