Refactor issue sidebar and fix various problems (#37045)

Fix various legacy problems, including:

* Don't create default column when viewing an empty project
* Fix layouts for Windows
* Fix (partially) #15509
* Fix (partially) #17705

The sidebar refactoring: it is a clear partial-reloading approach,
brings better user experiences, and it makes "Multiple projects" /
"Project column on issue sidebar" feature easy to be added.

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/repo/issue_new.go

@@ -121,11 +121,9 @@ func NewIssue(ctx *context.Context) {
 	}
 
 	pageMetaData.MilestonesData.SelectedMilestoneID = ctx.FormInt64("milestone")
-	pageMetaData.ProjectsData.SelectedProjectID = ctx.FormInt64("project")
-	if pageMetaData.ProjectsData.SelectedProjectID > 0 {
-		if len(ctx.Req.URL.Query().Get("project")) > 0 {
-			ctx.Data["redirect_after_creation"] = "project"
-		}
+	pageMetaData.ProjectsData.SelectedProjectIDs, _ = base.StringsToInt64s(strings.Split(ctx.FormString("project"), ","))
+	if len(pageMetaData.ProjectsData.SelectedProjectIDs) == 1 {
+		ctx.Data["redirect_after_creation"] = "project"
 	}
 
 	tags, err := repo_model.GetTagNamesByRepoID(ctx, ctx.Repo.Repository.ID)
@@ -273,7 +271,7 @@ func ValidateRepoMetasForNewIssue(ctx *context.Context, form forms.CreateIssueFo
 		ctx.NotFound(nil)
 		return ret
 	}
-	pageMetaData.ProjectsData.SelectedProjectID = form.ProjectID
+	pageMetaData.ProjectsData.SelectedProjectIDs = util.Iif(form.ProjectID > 0, []int64{form.ProjectID}, nil)
 
 	// prepare assignees
 	candidateAssignees := toSet(pageMetaData.AssigneesData.CandidateAssignees, func(user *user_model.User) int64 { return user.ID })

routers/web/repo/issue_page_meta.go

@@ -34,9 +34,14 @@ type issueSidebarAssigneesData struct {
 }
 
 type issueSidebarProjectsData struct {
-	SelectedProjectID int64
-	OpenProjects      []*project_model.Project
-	ClosedProjects    []*project_model.Project
+	SelectedProjectIDs []int64 // TODO: support multiple projects in the future
+
+	// the "selected" fields are only valid when len(SelectedProjectIDs)==1
+	SelectedProjectColumns []*project_model.Column
+	SelectedProjectColumn  *project_model.Column
+
+	OpenProjects   []*project_model.Project
+	ClosedProjects []*project_model.Project
 }
 
 type IssuePageMetaData struct {
@@ -92,6 +97,11 @@ func retrieveRepoIssueMetaData(ctx *context.Context, repo *repo_model.Repository
 		return data
 	}
 
+	data.retrieveProjectData(ctx)
+	if ctx.Written() {
+		return data
+	}
+
 	// TODO: the issue/pull permissions are quite complex and unclear
 	// A reader could create an issue/PR with setting some meta (eg: assignees from issue template, reviewers, target branch)
 	// A reader(creator) could update some meta (eg: target branch), but can't change assignees anymore.
@@ -158,9 +168,33 @@ func (d *IssuePageMetaData) retrieveAssigneesData(ctx *context.Context) {
 	ctx.Data["Assignees"] = d.AssigneesData.CandidateAssignees
 }
 
+func (d *IssuePageMetaData) retrieveProjectData(ctx *context.Context) {
+	if d.Issue == nil || d.Issue.Project == nil {
+		return
+	}
+	d.ProjectsData.SelectedProjectIDs = []int64{d.Issue.Project.ID}
+	columns, err := d.Issue.Project.GetColumns(ctx)
+	if err != nil {
+		ctx.ServerError("GetProjectColumns", err)
+		return
+	}
+	d.ProjectsData.SelectedProjectColumns = columns
+	columnID, err := d.Issue.ProjectColumnID(ctx)
+	if err != nil {
+		ctx.ServerError("ProjectColumnID", err)
+		return
+	}
+	for _, col := range columns {
+		if col.ID == columnID {
+			d.ProjectsData.SelectedProjectColumn = col
+			break
+		}
+	}
+}
+
 func (d *IssuePageMetaData) retrieveProjectsDataForIssueWriter(ctx *context.Context) {
 	if d.Issue != nil && d.Issue.Project != nil {
-		d.ProjectsData.SelectedProjectID = d.Issue.Project.ID
+		d.ProjectsData.SelectedProjectIDs = []int64{d.Issue.Project.ID}
 	}
 	d.ProjectsData.OpenProjects, d.ProjectsData.ClosedProjects = retrieveProjectsInternal(ctx, ctx.Repo.Repository)
 }