From ccdd85a5ebfbeaf2037d81cfd72f7f74e5a9e181 Mon Sep 17 00:00:00 2001
From: robford <robfordww@gmail.com>
Date: Fri, 20 Oct 2023 12:02:50 +0200
Subject: [PATCH] added ChopyFromCh

---
 copy_from.go | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/copy_from.go b/copy_from.go
index a2c227fd4..b15a0ae16 100644
--- a/copy_from.go
+++ b/copy_from.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"reflect"
 
 	"github.com/jackc/pgx/v5/internal/pgio"
 	"github.com/jackc/pgx/v5/pgconn"
@@ -64,6 +65,51 @@ func (cts *copyFromSlice) Err() error {
 	return cts.err
 }
 
+// CopyFromCh returns a CopyFromSource interface over the provided channel.
+// FieldNames is an ordered list of field names to copy from the struct, which
+// order must match the order of the columns.
+func CopyFromCh[T any](ch chan T, fieldNames []string) CopyFromSource {
+	return &copyFromCh[T]{c: ch, fieldNames: fieldNames}
+}
+
+type copyFromCh[T any] struct {
+	c          chan T
+	fieldNames []string
+	valueRow   []interface{}
+	err        error
+}
+
+func (g *copyFromCh[T]) Next() bool {
+	g.valueRow = g.valueRow[:0] // Clear buffer
+	val, ok := <-g.c
+	if !ok {
+		return false
+	}
+	// Handle both pointer to struct and struct
+	s := reflect.ValueOf(val)
+	if s.Kind() == reflect.Ptr {
+		s = s.Elem()
+	}
+
+	for i := 0; i < len(g.fieldNames); i++ {
+		f := s.FieldByName(g.fieldNames[i])
+		if !f.IsValid() {
+			g.err = fmt.Errorf("'%v' field not found in %#v", g.fieldNames[i], s.Interface())
+			return false
+		}
+		g.valueRow = append(g.valueRow, f.Interface())
+	}
+	return true
+}
+
+func (g *copyFromCh[T]) Values() ([]interface{}, error) {
+	return g.valueRow, nil
+}
+
+func (g *copyFromCh[T]) Err() error {
+	return g.err
+}
+
 // CopyFromSource is the interface used by *Conn.CopyFrom as the source for copy data.
 type CopyFromSource interface {
 	// Next returns true if there is another row and makes the next row data