fix on new Duplicate method

desc/argument.go

@@ -121,7 +121,9 @@ func filterArguments(args Arguments, filter func(arg Argument) bool) Arguments {
 
 // FilterArgumentsForInsert takes a slice of arguments and returns a slice of arguments for insert.
 func filterArgumentsForFullUpdate(args Arguments) Arguments {
-	return filterArguments(args, func(arg Argument) bool { return !arg.Column.IsGenerated() })
+	return filterArguments(args, func(arg Argument) bool {
+		return !arg.Column.IsGenerated() && !arg.Column.Presenter // && !arg.Column.Unscannable
+	})
 }
 
 // extractPrimaryKeyValues takes a table definition and a slice of reflect values of structs

desc/column.go

@@ -57,7 +57,7 @@ type (
 		// Unique indexes can really improve the performance on big data select queries
 		// Read more at: https://www.postgresql.org/docs/current/indexes-unique.html
 		UniqueIndex string // an optional name for a unique index on the column
-		// If true then create table and insert query will omit this column.
+		// If true then create table, insert, update and duplicate queries will omit this column.
 		Presenter bool
 		// If true then insert query will omit this column.
 		AutoGenerated bool

desc/duplicate_query.go

@@ -29,7 +29,7 @@ func BuildDuplicateQuery(td *Table, idPtr any) (string, error) {
 	// (name, tag, source_id)
 	b.WriteByte(leftParenLiteral)
 
-	columns := td.ListColumnsWithoutGenerated()
+	columns := td.listColumnsForSelectWithoutGenerated()
 	for i, c := range columns {
 		if i > 0 {
 			b.WriteByte(',')

desc/scanner.go

@@ -1,6 +1,7 @@
 package desc
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 
@@ -84,12 +85,25 @@ func ConvertRowsToStruct(td *Table, rows pgx.Rows, valuePtr interface{}) error {
 			if td.Strict {
 				return fmt.Errorf("struct doesn't have corresponding row field: %s (strict check)", rows.FieldDescriptions()[i].Name) // return an error if the struct doesn't have a field for a column
 			} else {
-				scanTargets[i] = &nullScanner{}
+				scanTargets[i] = &noOpScanner{}
 			}
 		}
 	}
 
 	if err = rows.Scan(scanTargets...); err != nil {
+		// Help developer to find what field was errored:
+		var scanArgErr pgx.ScanArgError
+		if errors.As(err, &scanArgErr) {
+			if len(td.Columns) > scanArgErr.ColumnIndex {
+				col := td.Columns[scanArgErr.ColumnIndex]
+				destColumnName := col.Name
+				err = fmt.Errorf("%w: field: %s.%s (%s): column: %s.%s",
+					err,
+					col.Table.StructName, col.FieldName, col.FieldType.String(),
+					col.TableName, destColumnName)
+			}
+		}
+
 		return err // return an error if scanning the row data failed
 	}
 
@@ -127,16 +141,36 @@ func findScanTargets(dstElemValue reflect.Value, td *Table, fieldDescs []pgconn.
 			}
 		}
 
+		if col.Type == UUID && col.Nullable {
+			scanTargets[i] = &nullableScanner{
+				uuidFieldPtr: dstElemValue.FieldByIndex(col.FieldIndex),
+			}
+
+			continue
+		}
+
 		// get the scan target by using the field index and taking the address and interface of the struct field
 		scanTargets[i] = dstElemValue.FieldByIndex(col.FieldIndex).Addr().Interface()
 	}
 
 	return scanTargets, nil // return the scan targets and nil error
 }
 
-type nullScanner struct{}
+type noOpScanner struct{}
+
+func (t *noOpScanner) Scan(src interface{}) error { return nil }
+
+type nullableScanner struct { // useful for UUIDs with null values.
+	uuidFieldPtr reflect.Value
+}
+
+func (t *nullableScanner) Scan(src interface{}) error {
+	if src == nil {
+		return nil
+	}
+
+	t.uuidFieldPtr.Set(reflect.ValueOf(src))
 
-func (t *nullScanner) Scan(src interface{}) error {
 	return nil
 }
 

desc/table.go

@@ -122,6 +122,24 @@ func (td *Table) ListColumnsWithoutGenerated() []*Column {
 	return columns
 }
 
+func (td *Table) listColumnsForSelectWithoutGenerated() []*Column {
+	columns := make([]*Column, 0, len(td.Columns))
+
+	for _, c := range td.Columns {
+		if c.IsGenerated() {
+			continue
+		}
+
+		if c.Presenter {
+			continue
+		}
+
+		columns = append(columns, c)
+	}
+
+	return columns
+}
+
 // ListColumnNames returns the column names of the table definition.
 func (td *Table) ListColumnNames() []string {
 	names := make([]string, 0, len(td.Columns))