CSV Writer: Allow different types in output

zio/csvio/writer.go

@@ -5,6 +5,7 @@ import (
  "errors"
  "fmt"
  "io"
+ "slices"
  "strings"
 
  "github.com/brimdata/zed"
@@ -19,6 +20,7 @@ type Writer struct {
  writer io.WriteCloser
  encoder *csv.Writer
  flattener *expr.Flattener
+ types map[int]struct{}
  first *zed.TypeRecord
  strings []string
 }
@@ -32,6 +34,7 @@ func NewWriter(w io.WriteCloser) *Writer {
  writer: w,
  encoder: csv.NewWriter(w),
  flattener: expr.NewFlattener(zed.NewContext()),
+ types: make(map[int]struct{}),
  }
 }
 
@@ -62,8 +65,11 @@ func (w *Writer) Write(rec *zed.Value) error {
  if err := w.encoder.Write(hdr); err != nil {
  return err
  }
- } else if rec.Type != w.first {
- return ErrNotDataFrame
+ } else if _, ok := w.types[rec.Type.ID()]; !ok {
+ if !fieldsEqual(w.first.Fields, rec.Fields()) {
+ return ErrNotDataFrame
+ }
+ w.types[rec.Type.ID()] = struct{}{}
  }
  w.strings = w.strings[:0]
  fields := rec.Fields()
@@ -96,3 +102,9 @@ func formatValue(typ zed.Type, bytes zcode.Bytes) string {
  }
  return zson.FormatValue(zed.NewValue(typ, bytes))
 }
+
+func fieldsEqual(a, b []zed.Field) bool {
+ return slices.EqualFunc(a, b, func(a, b zed.Field) bool {
+ return a.Name == b.Name
+ })
+}

zio/csvio/ztests/different-types.yaml

@@ -0,0 +1,14 @@
+zed: '*'
+
+input: |
+ {a:0}
+ {a:"foo"}
+ {a:127.0.0.1}
+
+output-flags: -f csv
+
+output: |
+ a
+ 0
+ foo
+ 127.0.0.1