🐛 Fix task filtering and sorting. (#659)

Fix issues reported
[here](konveyor/tackle2-ui#1931 (comment)).
1. sorting seems to work only for `id` field i.e. 
2. filtering not supported for `createUser` and `id` fields( both listed
in the enhancement)
3. application name is missing in the response and in filtering.
Filtering by application ID works but this is not so nice.
4. `priority` is missing in the response and in the filtering
5. for `kind` the filtering is supported by the server but it seems it's
not included in the response

---

Filter and sorting: needed to support GORM join queries which qualifies
fields by table.

Example: For a task query joined with application, produces all of the
task fields qualified as table.column:
```
SELECT task.id, task.name ...
```
And the (joined) application fields prefixed with `APPLICATION__`
```
SELECT APPLICATION__ID, APPLICATION__NAME ...
```

---------

Signed-off-by: Jeff Ortel <jortel@redhat.com>

api/filter/filter.go

@@ -332,13 +332,18 @@ func (f *Field) Expand() (expanded []Field) {
 // split field name.
 // format: resource.name
 // The resource may be "" (anonymous).
+// The (.) separator is escaped when preceded by (\).
 func (f *Field) split() (relation string, name string) {
 	s := f.Field.Value
 	mark := strings.Index(s, ".")
 	if mark == -1 {
 		name = s
 		return
 	}
+	if mark > 0 && s[mark-1] == '\\' {
+		name = s[:mark-1] + s[mark:]
+		return
+	}
 	relation = s[:mark]
 	name = s[mark+1:]
 	return

api/sort/sort.go

@@ -16,17 +16,29 @@ type Clause struct {
 
 // Sort provides sorting.
 type Sort struct {
-	fields  map[string]interface{}
+	fields  map[string]any
+	alias   map[string]string
 	clauses []Clause
 }
 
+// Add adds virtual field and aliases.
+func (r *Sort) Add(name string, aliases ...string) {
+	r.init()
+	for _, alias := range aliases {
+		alias = strings.ToLower(alias)
+		r.fields[alias] = 0
+		r.alias[alias] = name
+	}
+}
+
 // With context.
-func (r *Sort) With(ctx *gin.Context, m interface{}) (err error) {
+func (r *Sort) With(ctx *gin.Context, m any) (err error) {
 	param := ctx.Query("sort")
 	if param == "" {
 		return
 	}
-	r.fields = r.inspect(m)
+	r.init()
+	r.inspect(m)
 	for _, s := range strings.Split(param, ",") {
 		clause := Clause{}
 		s = strings.TrimSpace(s)
@@ -38,7 +50,7 @@ func (r *Sort) With(ctx *gin.Context, m interface{}) (err error) {
 				err = &SortError{s}
 				return
 			}
-			clause.name = s
+			clause.name = r.resolved(s)
 			r.clauses = append(
 				r.clauses,
 				clause)
@@ -55,7 +67,7 @@ func (r *Sort) With(ctx *gin.Context, m interface{}) (err error) {
 				err = &SortError{s}
 				return
 			}
-			clause.name = s
+			clause.name = r.resolved(s)
 			r.clauses = append(
 				r.clauses,
 				clause)
@@ -66,6 +78,7 @@ func (r *Sort) With(ctx *gin.Context, m interface{}) (err error) {
 
 // Sorted returns sorted DB.
 func (r *Sort) Sorted(in *gorm.DB) (out *gorm.DB) {
+	r.init()
 	out = in
 	if len(r.clauses) == 0 {
 		return
@@ -78,11 +91,33 @@ func (r *Sort) Sorted(in *gorm.DB) (out *gorm.DB) {
 	return
 }
 
+// init allocate maps.
+func (r *Sort) init() {
+	if r.fields == nil {
+		r.fields = make(map[string]any)
+	}
+	if r.alias == nil {
+		r.alias = make(map[string]string)
+	}
+}
+
 // inspect object and return fields.
-func (r *Sort) inspect(m interface{}) (fields map[string]interface{}) {
-	fields = reflect.Fields(m)
-	for key, v := range fields {
-		fields[strings.ToLower(key)] = v
+func (r *Sort) inspect(m any) {
+	r.init()
+	for key, v := range reflect.Fields(m) {
+		key = strings.ToLower(key)
+		r.fields[key] = v
+	}
+	return
+}
+
+// resolved returns field names with alias resolved.
+func (r *Sort) resolved(in string) (out string) {
+	r.init()
+	out = in
+	alias, found := r.alias[in]
+	if found {
+		out = alias
 	}
 	return
 }

api/task.go

@@ -114,26 +114,32 @@ func (h TaskHandler) Get(ctx *gin.Context) {
 // @description List all tasks.
 // @description Filters:
 // @description - kind
+// @description - createUser
 // @description - addon
 // @description - name
 // @description - locator
 // @description - state
 // @description - application.id
+// @description - application.name
 // @description The state=queued is an alias for queued states.
 // @tags tasks
 // @produce json
 // @success 200 {object} []api.Task
 // @router /tasks [get]
 func (h TaskHandler) List(ctx *gin.Context) {
 	resources := []Task{}
+	// filter
 	filter, err := qf.New(ctx,
 		[]qf.Assert{
+			{Field: "id", Kind: qf.LITERAL},
+			{Field: "createUser", Kind: qf.STRING},
 			{Field: "kind", Kind: qf.STRING},
 			{Field: "addon", Kind: qf.STRING},
 			{Field: "name", Kind: qf.STRING},
 			{Field: "locator", Kind: qf.STRING},
 			{Field: "state", Kind: qf.STRING},
 			{Field: "application.id", Kind: qf.STRING},
+			{Field: "application.name", Kind: qf.STRING},
 		})
 	if err != nil {
 		_ = ctx.Error(err)
@@ -157,17 +163,28 @@ func (h TaskHandler) List(ctx *gin.Context) {
 		values = values.Join(qf.OR)
 		filter = filter.Revalued("state", values)
 	}
+	filter = filter.Renamed("application.id", "application__id")
+	filter = filter.Renamed("application.name", "application__name")
+	filter = filter.Renamed("createUser", "task\\.createUser")
+	filter = filter.Renamed("id", "task\\.id")
+	filter = filter.Renamed("name", "task\\.name")
+	// sort
 	sort := Sort{}
-	err = sort.With(ctx, &model.Issue{})
+	sort.Add("task.id", "id")
+	sort.Add("task.createUser", "createUser")
+	sort.Add("task.name", "name")
+	sort.Add("application__id", "application.id")
+	sort.Add("application__name", "application.name")
+	err = sort.With(ctx, &model.Task{})
 	if err != nil {
 		_ = ctx.Error(err)
 		return
 	}
+	// Fetch
 	db := h.DB(ctx)
 	db = db.Model(&model.Task{})
-	db = db.Preload(clause.Associations)
+	db = db.Joins("Application")
 	db = sort.Sorted(db)
-	filter = filter.Renamed("application.id", "applicationId")
 	db = filter.Where(db)
 	var m model.Task
 	var list []model.Task