cli/sql: new output format json alongside ndjson

Release note (cli change): The CLI commands that output SQL data
now support the output format JSON (`--format=json`), in addition
to newline-delimited JSON (ND-JSON, `--format=ndjson`) that had been
supported since v22.2.

pkg/cli/clisqlexec/format_json.go

@@ -15,43 +15,67 @@ import (
 	"io"
 )
 
-type ndjsonReporter struct {
-	cols []string
+type jsonReporter struct {
+	start, end, middle []byte
+	currentPrefix      []byte
+	cols               []string
+	rowMap             map[string]string
 }
 
-func (n *ndjsonReporter) describe(w io.Writer, cols []string) error {
+func (n *jsonReporter) describe(w io.Writer, cols []string) error {
 	n.cols = cols
-	return nil
+	n.rowMap = make(map[string]string, len(cols))
+	for _, col := range cols {
+		n.rowMap[col] = ""
+	}
+	_, err := w.Write(n.start)
+	return err
 }
 
-func (n *ndjsonReporter) beforeFirstRow(w io.Writer, allRows RowStrIter) error {
+func (n *jsonReporter) beforeFirstRow(w io.Writer, allRows RowStrIter) error {
 	return nil
 }
 
-func (n *ndjsonReporter) iter(w, ew io.Writer, rowIdx int, row []string) error {
-	retMap := make(map[string]string, len(row))
+func (n *jsonReporter) iter(w, ew io.Writer, rowIdx int, row []string) error {
 	for i := range row {
-		retMap[n.cols[i]] = row[i]
+		n.rowMap[n.cols[i]] = row[i]
 	}
-	out, err := json.Marshal(retMap)
+	out, err := json.Marshal(n.rowMap)
 	if err != nil {
 		return err
 	}
-	if _, err := w.Write(out); err != nil {
+	if _, err := w.Write(n.currentPrefix); err != nil {
 		return err
 	}
-	if _, err := w.Write(newLineChar); err != nil {
+	n.currentPrefix = n.middle
+	if _, err := w.Write(out); err != nil {
 		return err
 	}
 	return nil
 }
 
-var newLineChar = []byte("\n")
+func (n *jsonReporter) doneRows(w io.Writer, seenRows int) error {
+	_, err := w.Write(n.end)
+	return err
+}
 
-func (n *ndjsonReporter) doneRows(w io.Writer, seenRows int) error {
-	return nil
+func (n *jsonReporter) doneNoRows(w io.Writer) error {
+	_, err := w.Write(n.end)
+	return err
 }
 
-func (n *ndjsonReporter) doneNoRows(w io.Writer) error {
-	return nil
+func makeJSONReporter(format TableDisplayFormat) *jsonReporter {
+	r := &jsonReporter{
+		start:         []byte("["),
+		end:           []byte("\n]\n"),
+		middle:        []byte(",\n  "),
+		currentPrefix: []byte("\n  "),
+	}
+	if format == TableDisplayNDJSON {
+		r.start = nil
+		r.currentPrefix = nil
+		r.end = []byte("\n")
+		r.middle = []byte("\n")
+	}
+	return r
 }

pkg/cli/clisqlexec/format_table.go

@@ -254,7 +254,9 @@ func (sqlExecCtx *Context) makeReporter(w io.Writer) (rowReporter, func(), error
 		return reporter, cleanup, nil
 
 	case TableDisplayNDJSON:
-		return &ndjsonReporter{}, nil, nil
+		fallthrough
+	case TableDisplayJSON:
+		return makeJSONReporter(sqlExecCtx.TableDisplayFormat), nil, nil
 
 	case TableDisplayRaw:
 		return &rawReporter{}, nil, nil

pkg/cli/clisqlexec/format_table_test.go

@@ -136,6 +136,10 @@ thenshort`,
 	// ܈85            | 0
 	// sql --format=ndjson -e select * from t.u
 	// {"a|b":"0","f\"oo":"0","f'oo":"0","f\\oo":"0","short\nvery very long\nnot much":"0","very very long\nthenshort":"0","κόσμε":"0","܈85":"0"}
+	// sql --format=json -e select * from t.u
+	// [
+	//   {"a|b":"0","f\"oo":"0","f'oo":"0","f\\oo":"0","short\nvery very long\nnot much":"0","very very long\nthenshort":"0","κόσμε":"0","܈85":"0"}
+	// ]
 	// sql --format=sql -e select * from t.u
 	// CREATE TABLE results (
 	//   "f""oo" STRING,
@@ -220,6 +224,10 @@ func Example_sql_empty_table() {
 	// (0 rows)
 	// sql --format=records -e select * from t.norows
 	// sql --format=ndjson -e select * from t.norows
+	//
+	// sql --format=json -e select * from t.norows
+	// [
+	// ]
 	// sql --format=sql -e select * from t.norows
 	// CREATE TABLE results (
 	//   x STRING
@@ -258,6 +266,12 @@ func Example_sql_empty_table() {
 	// {}
 	// {}
 	// {}
+	// sql --format=json -e select * from t.nocols
+	// [
+	//   {},
+	//   {},
+	//   {}
+	// ]
 	// sql --format=sql -e select * from t.nocols
 	// CREATE TABLE results (
 	// );
@@ -300,6 +314,10 @@ func Example_sql_empty_table() {
 	// sql --format=records -e select * from t.nocolsnorows
 	// (0 rows)
 	// sql --format=ndjson -e select * from t.nocolsnorows
+	//
+	// sql --format=json -e select * from t.nocolsnorows
+	// [
+	// ]
 	// sql --format=sql -e select * from t.nocolsnorows
 	// CREATE TABLE results (
 	// );
@@ -626,6 +644,18 @@ func Example_sql_table() {
 	// {"d":"non-printable UTF8 string","s":"\\x01"}
 	// {"d":"UTF8 string with RTL char","s":"܈85"}
 	// {"d":"tabs","s":"a\tb\tc\n12\t123123213\t12313"}
+	// sql --format=json -e select * from t.t
+	// [
+	//   {"d":"printable ASCII","s":"foo"},
+	//   {"d":"printable ASCII with quotes","s":"\"foo"},
+	//   {"d":"printable ASCII with backslash","s":"\\foo"},
+	//   {"d":"non-printable ASCII","s":"foo\nbar"},
+	//   {"d":"printable UTF8","s":"κόσμε"},
+	//   {"d":"printable UTF8 using escapes","s":"ñ"},
+	//   {"d":"non-printable UTF8 string","s":"\\x01"},
+	//   {"d":"UTF8 string with RTL char","s":"܈85"},
+	//   {"d":"tabs","s":"a\tb\tc\n12\t123123213\t12313"}
+	// ]
 	// sql --format=sql -e select * from t.t
 	// CREATE TABLE results (
 	//   s STRING,

pkg/cli/clisqlexec/table_display_format.go

@@ -37,9 +37,11 @@ const (
 	// TableDisplayRecords is a record-oriented format. It is somewhat
 	// compatible with 'psql' "expanded display" mode.
 	TableDisplayRecords
-	// TableDisplayNDJSON reports results in an nd-json format
-	// (https://github.com/ndjson/ndjson-spec).
+	// TableDisplayNDJSON reports results in an newlined-delimited JSON
+	// format (https://github.com/ndjson/ndjson-spec).
 	TableDisplayNDJSON
+	// TableDisplayJSON reports results using JSON.
+	TableDisplayJSON
 	// TableDisplaySQL reports results using SQL statements that mimic
 	// the creation of a SQL table containing the result values.
 	TableDisplaySQL
@@ -95,6 +97,8 @@ func (f *TableDisplayFormat) String() string {
 		return "sql"
 	case TableDisplayNDJSON:
 		return "ndjson"
+	case TableDisplayJSON:
+		return "json"
 	case TableDisplayHTML:
 		return "html"
 	case TableDisplayRawHTML:
@@ -120,6 +124,8 @@ func (f *TableDisplayFormat) Set(s string) error {
 		*f = TableDisplaySQL
 	case "ndjson":
 		*f = TableDisplayNDJSON
+	case "json":
+		*f = TableDisplayJSON
 	case "html":
 		*f = TableDisplayHTML
 	case "rawhtml":

pkg/cli/clisqlshell/sql_test.go

@@ -163,10 +163,10 @@ func Example_sql_config() {
 	// HINT: Try \? for help.
 	// sql --set display_format=invalidvalue -e select 123 as "123"
 	// ERROR: -e: \set display_format=invalidvalue: invalid table display format: invalidvalue
-	// HINT: Possible values: tsv, csv, table, records, ndjson, sql, html, raw.
+	// HINT: Possible values: tsv, csv, table, records, ndjson, json, sql, html, raw.
 	// sql -e \set display_format=invalidvalue -e select 123 as "123"
 	// ERROR: -e: \set display_format=invalidvalue: invalid table display format: invalidvalue
-	// HINT: Possible values: tsv, csv, table, records, ndjson, sql, html, raw.
+	// HINT: Possible values: tsv, csv, table, records, ndjson, json, sql, html, raw.
 }
 
 func Example_sql_watch() {