Follow delvh's suggestion

models/project/board.go

@@ -208,7 +208,7 @@ func deleteBoardByID(ctx context.Context, boardID int64) error {
 		return err
 	}
 
-	if err = board.moveIssuesToAnotherColumn(ctx, defaultColumn.ID); err != nil {
+	if err = board.moveIssuesToAnotherColumn(ctx, defaultColumn); err != nil {
 		return err
 	}
 
@@ -330,11 +330,13 @@ func UpdateBoardSorting(ctx context.Context, bs BoardList) error {
 	})
 }
 
-func GetColumnsByIDs(ctx context.Context, columnsIDs []int64) (BoardList, error) {
+func GetColumnsByIDs(ctx context.Context, projectID int64, columnsIDs []int64) (BoardList, error) {
 	columns := make([]*Board, 0, 5)
-	if err := db.GetEngine(ctx).In("id", columnsIDs).OrderBy("sorting").Find(&columns); err != nil {
+	if err := db.GetEngine(ctx).
+		Where("project_id =?", projectID).
+		In("id", columnsIDs).
+		OrderBy("sorting").Find(&columns); err != nil {
 		return nil, err
 	}
-
 	return columns, nil
 }

models/project/issue.go

@@ -5,9 +5,11 @@ package project
 
 import (
 	"context"
+	"errors"
 	"fmt"
 
 	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/log"
 )
 
@@ -102,34 +104,38 @@ func MoveIssuesOnProjectBoard(ctx context.Context, board *Board, sortedIssueIDs
 	})
 }
 
-func (b *Board) moveIssuesToAnotherColumn(ctx context.Context, columnID int64) error {
-	if b.ID == columnID {
+func (b *Board) moveIssuesToAnotherColumn(ctx context.Context, newColumn *Board) error {
+	if b.ID == newColumn.ID {
 		return nil
 	}
-	_, err := db.GetEngine(ctx).Exec("UPDATE `project_issue` SET project_board_id = ? WHERE project_board_id = ? ", columnID, b.ID)
+	if b.ProjectID != newColumn.ProjectID {
+		return fmt.Errorf("columns have to be in the same project")
+	}
+	_, err := db.GetEngine(ctx).Exec("UPDATE `project_issue` SET project_board_id = ? WHERE project_board_id = ? ", newColumn.ID, b.ID)
 	return err
 }
 
-// MoveColumnsOnProject moves or keeps issues in a column and sorts them inside that column
+// MoveColumnsOnProject moves or keeps column in a project and sorts them inside that column
 func MoveColumnsOnProject(ctx context.Context, project *Project, sortedColumnIDs map[int64]int64) error {
 	return db.WithTx(ctx, func(ctx context.Context) error {
 		sess := db.GetEngine(ctx)
-
-		columnIDs := make([]int64, 0, len(sortedColumnIDs))
-		for _, columnID := range sortedColumnIDs {
-			columnIDs = append(columnIDs, columnID)
-		}
-		count, err := sess.Table(new(Board)).Where("project_id=?", project.ID).In("id", columnIDs).Count()
+		columnIDs := container.MapValues(sortedColumnIDs)
+		movedColumns, err := GetColumnsByIDs(ctx, project.ID, columnIDs)
 		if err != nil {
 			return err
 		}
-		if int(count) != len(sortedColumnIDs) {
-			return fmt.Errorf("all issues have to be added to a project first")
+		if len(movedColumns) != len(sortedColumnIDs) {
+			return errors.New("some columns do not exist")
+		}
+
+		for _, column := range movedColumns {
+			if column.ProjectID != project.ID {
+				return errors.New("Some column's projectID is not equal to project's ID")
+			}
 		}
 
 		for sorting, columnID := range sortedColumnIDs {
-			_, err = sess.Exec("UPDATE `project_board` SET sorting=? WHERE id=?", sorting, columnID)
-			if err != nil {
+			if _, err := sess.Exec("UPDATE `project_board` SET sorting=? WHERE id=?", sorting, columnID); err != nil {
 				return err
 			}
 		}

modules/container/map.go

@@ -0,0 +1,14 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package container
+
+// MapValues returns a slice of all values in a map.
+// TODO: remove this after Golang std lib has similar function but not golang.org/x/exp
+func MapValues[K comparable, V any](m map[K]V) []V {
+	values := make([]V, 0, len(m))
+	for _, v := range m {
+		values = append(values, v)
+	}
+	return values
+}

routers/web/shared/project/column.go

@@ -4,8 +4,6 @@
 package project
 
 import (
-	"errors"
-
 	issues_model "code.gitea.io/gitea/models/issues"
 	project_model "code.gitea.io/gitea/models/project"
 	"code.gitea.io/gitea/modules/json"
@@ -41,32 +39,13 @@ func MoveColumns(ctx *context.Context) {
 		return
 	}
 
-	columnIDs := make([]int64, 0, len(form.Columns))
 	sortedColumnIDs := make(map[int64]int64)
 	for _, column := range form.Columns {
-		columnIDs = append(columnIDs, column.ColumnID)
 		sortedColumnIDs[column.Sorting] = column.ColumnID
 	}
-	movedColumns, err := project_model.GetColumnsByIDs(ctx, columnIDs)
-	if err != nil {
-		ctx.NotFoundOrServerError("GetColumnsByIDs", issues_model.IsErrIssueNotExist, err)
-		return
-	}
-
-	if len(movedColumns) != len(form.Columns) {
-		ctx.ServerError("some columns do not exist", errors.New("some columns do not exist"))
-		return
-	}
-
-	for _, column := range movedColumns {
-		if column.ProjectID != project.ID {
-			ctx.ServerError("Some column's projectID is not equal to project's ID", errors.New("Some column's projectID is not equal to project's ID"))
-			return
-		}
-	}
 
 	if err = project_model.MoveColumnsOnProject(ctx, project, sortedColumnIDs); err != nil {
-		ctx.ServerError("MoveColumnsOnProject", err)
+		ctx.NotFoundOrServerError("MoveColumnsOnProject", issues_model.IsErrIssueNotExist, err)
 		return
 	}