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themis/fmt.go

70 lines
1.5 KiB

package themis
import (
"database/sql"
"fmt"
"strings"
)
func FormatRows(rows *sql.Rows) (string, error) {
sb := strings.Builder{}
cols, err := rows.Columns()
if err != nil {
return "", fmt.Errorf("failed to get rows columns: %w", err)
}
c := make([]string, len(cols))
for i := range c {
c[i] = " %-*s "
}
pattern := fmt.Sprintf("|%s|\n", strings.Join(c, "|"))
lengths := make([]int, len(cols))
for i := range lengths {
lengths[i] = len(cols[i])
}
scanned := make([][]any, 0)
for rows.Next() {
row := make([]interface{}, len(cols))
for i := range row {
row[i] = new(string)
}
rows.Scan(row...)
scanned = append(scanned, row) // keep track of row for later
for i, a := range row {
s := a.(*string)
if len(*s) > lengths[i] {
lengths[i] = len(*s)
}
}
}
// Write column names
curr := make([]any, 0, 2*len(cols))
for i := range lengths {
curr = append(curr, lengths[i], cols[i])
}
sb.WriteString(fmt.Sprintf(pattern, curr...))
// Write header separator row
curr = curr[:0] // empty slice but preserve capacity
for i := range lengths {
curr = append(curr, lengths[i], strings.Repeat("-", lengths[i]))
}
sb.WriteString(fmt.Sprintf(pattern, curr...))
// iterate rows and write each one
for _, r := range scanned {
curr = curr[:0] // empty slice but preserve capacity
for i := range lengths {
s := r[i].(*string)
curr = append(curr, lengths[i], *s)
}
sb.WriteString(fmt.Sprintf(pattern, curr...))
}
return sb.String(), nil
}