graphql: handle unknown property in MapFilter

Handling unknown GraphQL filter property in MapFilter func.
It is required to fallback into selector filtering when
the specified property is not available in the search response.
E.g. ?filter=(eq,location,US) --> should filter using the selector.

internal/graphql/graphql.go

@@ -15,6 +15,7 @@ License.
 package graphql
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/openshift-kni/oran-o2ims/internal/model"
@@ -99,6 +100,9 @@ func (t FilterTerm) MapFilter(mapPropertyFunc func(string) string) (searchFilter
 
 	// Convert to GraphQL property
 	searchProperty := mapPropertyFunc(t.Path[0])
+	if searchProperty == "" {
+		return nil, errors.New("unknown GraphQL property")
+	}
 
 	// Build search filter
 	searchFilter = &model.SearchFilter{

internal/graphql/graphql_test.go

@@ -15,6 +15,8 @@ License.
 package graphql
 
 import (
+	"errors"
+
 	"github.com/openshift-kni/oran-o2ims/internal/model"
 	"github.com/openshift-kni/oran-o2ims/internal/search"
 
@@ -27,10 +29,14 @@ import (
 var _ = Describe("GraphQL filters", func() {
 	DescribeTable(
 		"Map a filter term to a SearchFilter",
-		func(term search.Term, expected *model.SearchFilter, mapPropertyFunc func(string) string) {
+		func(term search.Term, expectedFilter *model.SearchFilter, expectedErr error, mapPropertyFunc func(string) string) {
 			actual, err := FilterTerm(term).MapFilter(mapPropertyFunc)
-			Expect(err).ToNot(HaveOccurred())
-			Expect(actual).To(Equal(expected))
+			Expect(actual).To(Equal(expectedFilter))
+			if expectedErr != nil {
+				Expect(err).To(HaveOccurred())
+			} else {
+				Expect(err).ToNot(HaveOccurred())
+			}
 		},
 		Entry(
 			"Filter term for Cluster",
@@ -47,6 +53,7 @@ var _ = Describe("GraphQL filters", func() {
 				Property: "cluster",
 				Values:   []*string{ptr.To("=spoke0")},
 			},
+			nil,
 			func(s string) string {
 				return PropertyCluster(s).MapProperty()
 			},
@@ -66,6 +73,24 @@ var _ = Describe("GraphQL filters", func() {
 				Property: "cluster",
 				Values:   []*string{ptr.To("=spoke0")},
 			},
+			nil,
+			func(s string) string {
+				return PropertyNode(s).MapProperty()
+			},
+		),
+		Entry(
+			"Fail when an unknown property is specified",
+			search.Term{
+				Operator: search.Eq,
+				Path: []string{
+					"location",
+				},
+				Values: []any{
+					"EU",
+				},
+			},
+			nil,
+			errors.New("unknown GraphQL property"),
 			func(s string) string {
 				return PropertyNode(s).MapProperty()
 			},