feature to be able to filter project boards by milestones (#36321)

This pull request adds milestone filtering support to both repository
and organization project boards. Users can now filter project issues by
milestone, similar to how they filter by label or assignee. The
implementation includes backend changes to fetch and filter milestones,
as well as frontend updates to display a milestone filter dropdown in
the project board UI.

**Milestone filtering support:**

* Added support for filtering project board issues by milestone in both
repository and organization contexts, including handling for "no
milestone" and "all milestones" options. (`routers/web/repo/projects.go`
[[1]](diffhunk://#diff-5cba331a1ddf1eea017178cfefaaff9ad72a4b05797fb84bf508b0939aae2972R316-R330)
[[2]](diffhunk://#diff-5cba331a1ddf1eea017178cfefaaff9ad72a4b05797fb84bf508b0939aae2972R421-R441);
`routers/web/org/projects.go`
[[3]](diffhunk://#diff-f4279417070a8e33829c338abeb42877500377f490abb1495ae6357d50b6a765R344-R357)
[[4]](diffhunk://#diff-f4279417070a8e33829c338abeb42877500377f490abb1495ae6357d50b6a765R433-R485)
* Updated the project board template to include a milestone filter
dropdown, displaying open and closed milestones and integrating with the
query string for filtering. (`templates/projects/view.tmpl`
[[1]](diffhunk://#diff-e2c7e14d247ce381c352263a8fa639b8341690ff85f6dbebfa166ee3306542feL8-R8)
[[2]](diffhunk://#diff-e2c7e14d247ce381c352263a8fa639b8341690ff85f6dbebfa166ee3306542feR19-R58)

Solves Issue #35224

---------

Signed-off-by: josetduarte <6619440+josetduarte@users.noreply.github.com>
Co-authored-by: joseduarte <joseduarte@aidhound.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

routers/web/org/projects.go

@@ -13,7 +13,7 @@ import (
 	issues_model "code.gitea.io/gitea/models/issues"
 	org_model "code.gitea.io/gitea/models/organization"
 	project_model "code.gitea.io/gitea/models/project"
-	attachment_model "code.gitea.io/gitea/models/repo"
+	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unit"
 	"code.gitea.io/gitea/modules/json"
 	"code.gitea.io/gitea/modules/optional"
@@ -25,6 +25,8 @@ import (
 	"code.gitea.io/gitea/services/context"
 	"code.gitea.io/gitea/services/forms"
 	project_service "code.gitea.io/gitea/services/projects"
+
+	"xorm.io/builder"
 )
 
 const (
@@ -332,12 +334,26 @@ func ViewProject(ctx *context.Context) {
 		return
 	}
 	assigneeID := ctx.FormString("assignee")
+	milestoneID := ctx.FormInt64("milestone")
+
+	// Prepare milestone IDs for filtering
+	var milestoneIDs []int64
+	if milestoneID > 0 {
+		milestoneIDs = []int64{milestoneID}
+	} else if milestoneID == db.NoConditionID {
+		milestoneIDs = []int64{db.NoConditionID}
+	}
 
 	opts := issues_model.IssuesOptions{
-		LabelIDs:   preparedLabelFilter.SelectedLabelIDs,
-		AssigneeID: assigneeID,
-		Owner:      project.Owner,
-		Doer:       ctx.Doer,
+		LabelIDs:     preparedLabelFilter.SelectedLabelIDs,
+		AssigneeID:   assigneeID,
+		MilestoneIDs: milestoneIDs,
+		Owner:        project.Owner,
+	}
+	if ctx.Doer != nil {
+		opts.Doer = ctx.Doer
+	} else {
+		opts.AllPublic = true
 	}
 
 	issuesMap, err := project_service.LoadIssuesFromProject(ctx, project, &opts)
@@ -350,10 +366,10 @@ func ViewProject(ctx *context.Context) {
 	}
 
 	if project.CardType != project_model.CardTypeTextOnly {
-		issuesAttachmentMap := make(map[int64][]*attachment_model.Attachment)
+		issuesAttachmentMap := make(map[int64][]*repo_model.Attachment)
 		for _, issuesList := range issuesMap {
 			for _, issue := range issuesList {
-				if issueAttachment, err := attachment_model.GetAttachmentsByIssueIDImagesLatest(ctx, issue.ID); err == nil {
+				if issueAttachment, err := repo_model.GetAttachmentsByIssueIDImagesLatest(ctx, issue.ID); err == nil {
 					issuesAttachmentMap[issue.ID] = issueAttachment
 				}
 			}
@@ -411,6 +427,42 @@ func ViewProject(ctx *context.Context) {
 	ctx.Data["Labels"] = labels
 	ctx.Data["NumLabels"] = len(labels)
 
+	// Get milestones for filtering
+	// For organization projects, we need to get milestones from all repos the user has access to
+	var milestones issues_model.MilestoneList
+	if project.RepoID > 0 {
+		// Repo-specific project
+		milestones, err = db.Find[issues_model.Milestone](ctx, issues_model.FindMilestoneOptions{
+			RepoID: project.RepoID,
+		})
+		if err != nil {
+			ctx.ServerError("GetRepoMilestones", err)
+			return
+		}
+	} else {
+		// Organization-wide project - get milestones from all organization repos
+		// but only from repositories the current user can access.
+		// Use RepoCond with a subquery to avoid materializing all repo IDs in memory
+		// which can hit SQL parameter limits for orgs with many repos.
+		accessCond := repo_model.AccessibleRepositoryCondition(ctx.Doer, unit.TypeIssues)
+		repoCond := builder.And(
+			builder.Eq{"owner_id": project.OwnerID},
+			accessCond,
+		)
+		milestones, err = db.Find[issues_model.Milestone](ctx, issues_model.FindMilestoneOptions{
+			RepoCond: repoCond,
+		})
+		if err != nil {
+			ctx.ServerError("GetOrgMilestones", err)
+			return
+		}
+	}
+
+	openMilestones, closedMilestones := milestones.SplitByOpenClosed()
+	ctx.Data["OpenMilestones"] = openMilestones
+	ctx.Data["ClosedMilestones"] = closedMilestones
+	ctx.Data["MilestoneID"] = milestoneID
+
 	// Get assignees.
 	assigneeUsers, err := org_model.GetOrgAssignees(ctx, project.OwnerID)
 	if err != nil {

routers/web/repo/issue_list.go

@@ -462,14 +462,7 @@ func renderMilestones(ctx *context.Context) {
 		return
 	}
 
-	openMilestones, closedMilestones := issues_model.MilestoneList{}, issues_model.MilestoneList{}
-	for _, milestone := range milestones {
-		if milestone.IsClosed {
-			closedMilestones = append(closedMilestones, milestone)
-		} else {
-			openMilestones = append(openMilestones, milestone)
-		}
-	}
+	openMilestones, closedMilestones := issues_model.MilestoneList(milestones).SplitByOpenClosed()
 	ctx.Data["OpenMilestones"] = openMilestones
 	ctx.Data["ClosedMilestones"] = closedMilestones
 }

routers/web/repo/projects.go

@@ -311,13 +311,25 @@ func ViewProject(ctx *context.Context) {
 	}
 
 	preparedLabelFilter := issue.PrepareFilterIssueLabels(ctx, ctx.Repo.Repository.ID, ctx.Repo.Owner)
+	if ctx.Written() {
+		return
+	}
 
 	assigneeID := ctx.FormString("assignee")
+	milestoneID := ctx.FormInt64("milestone")
+
+	var milestoneIDs []int64
+	if milestoneID > 0 {
+		milestoneIDs = []int64{milestoneID}
+	} else if milestoneID == db.NoConditionID {
+		milestoneIDs = []int64{db.NoConditionID}
+	}
 
 	issuesMap, err := project_service.LoadIssuesFromProject(ctx, project, &issues_model.IssuesOptions{
-		RepoIDs:    []int64{ctx.Repo.Repository.ID},
-		LabelIDs:   preparedLabelFilter.SelectedLabelIDs,
-		AssigneeID: assigneeID,
+		RepoIDs:      []int64{ctx.Repo.Repository.ID},
+		LabelIDs:     preparedLabelFilter.SelectedLabelIDs,
+		AssigneeID:   assigneeID,
+		MilestoneIDs: milestoneIDs,
 	})
 	if err != nil {
 		ctx.ServerError("LoadIssuesOfColumns", err)
@@ -408,6 +420,12 @@ func ViewProject(ctx *context.Context) {
 	ctx.Data["Assignees"] = shared_user.MakeSelfOnTop(ctx.Doer, assigneeUsers)
 	ctx.Data["AssigneeID"] = assigneeID
 
+	renderMilestones(ctx)
+	if ctx.Written() {
+		return
+	}
+	ctx.Data["MilestoneID"] = milestoneID
+
 	rctx := renderhelper.NewRenderContextRepoComment(ctx, ctx.Repo.Repository)
 	project.RenderedContent, err = markdown.RenderString(rctx, project.Description)
 	if err != nil {