feat(dataservices): abstract away some redundant code EE-5620 (#9110)

api/dataservices/helpers.go

@@ -0,0 +1,68 @@
+package dataservices
+
+import (
+	"errors"
+	"fmt"
+
+	perrors "github.com/portainer/portainer/api/dataservices/errors"
+
+	"github.com/rs/zerolog/log"
+)
+
+// ErrStop signals the stop of computation when filtering results
+var ErrStop = errors.New("stop")
+
+func IsErrObjectNotFound(e error) bool {
+	return errors.Is(e, perrors.ErrObjectNotFound)
+}
+
+// AppendFn appends elements to the given collection slice
+func AppendFn[T any](collection *[]T) func(obj interface{}) (interface{}, error) {
+	return func(obj interface{}) (interface{}, error) {
+		element, ok := obj.(*T)
+		if !ok {
+			log.Debug().Str("obj", fmt.Sprintf("%#v", obj)).Msg("type assertion failed")
+			return nil, fmt.Errorf("failed to convert to %T object: %#v", new(T), obj)
+		}
+
+		*collection = append(*collection, *element)
+
+		return new(T), nil
+	}
+}
+
+// FilterFn appends elements to the given collection when the predicate is true
+func FilterFn[T any](collection *[]T, predicate func(T) bool) func(obj interface{}) (interface{}, error) {
+	return func(obj interface{}) (interface{}, error) {
+		element, ok := obj.(*T)
+		if !ok {
+			log.Debug().Str("obj", fmt.Sprintf("%#v", obj)).Msg("type assertion failed")
+			return nil, fmt.Errorf("failed to convert to %T object: %#v", new(T), obj)
+		}
+
+		if predicate(*element) {
+			*collection = append(*collection, *element)
+		}
+
+		return new(T), nil
+	}
+}
+
+// FirstFn sets the element to the first one that satisfies the predicate and stops the computation, returns ErrStop on
+// success
+func FirstFn[T any](element *T, predicate func(T) bool) func(obj interface{}) (interface{}, error) {
+	return func(obj interface{}) (interface{}, error) {
+		e, ok := obj.(*T)
+		if !ok {
+			log.Debug().Str("obj", fmt.Sprintf("%#v", obj)).Msg("type assertion failed")
+			return nil, fmt.Errorf("failed to convert to %T object: %#v", new(T), obj)
+		}
+
+		if predicate(*e) {
+			*element = *e
+			return new(T), ErrStop
+		}
+
+		return new(T), nil
+	}
+}