Add GetNodeProperty and GetRelationshipProperty top-level APIs

These are generic helpers to extract properties from nodes and
relationships in a type-safe way.

Relates to #373

neo4j/graph.go

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [https://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package neo4j
+
+import (
+	"fmt"
+)
+
+// GetNodeProperty returns the value matching the property of the given neo4j.Node
+// If the property does not exist, an error is returned
+// If the property type does not match the type specification, an error is also returned
+func GetNodeProperty[T any](entity Node, key string) (T, error) {
+	return getProperty[T](entity.Props, key)
+}
+
+// GetRelationshipProperty returns the value matching the property of the given neo4j.Relationship
+// If the property does not exist, an error is returned
+// If the property type does not match the type specification, an error is also returned
+func GetRelationshipProperty[T any](entity Relationship, key string) (T, error) {
+	return getProperty[T](entity.Props, key)
+}
+
+func getProperty[T any](props map[string]any, key string) (T, error) {
+	rawValue, found := props[key]
+	if !found {
+		return *new(T), fmt.Errorf("could not find any property named %s", key)
+	}
+	value, ok := rawValue.(T)
+	if !ok {
+		zeroValue := *new(T)
+		return zeroValue, fmt.Errorf("expected value to have type %T but found type %T", zeroValue, rawValue)
+	}
+	return value, nil
+}

neo4j/graph_test.go

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [https://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package neo4j_test
+
+import (
+	"github.com/neo4j/neo4j-go-driver/v5/neo4j"
+	"testing"
+	"testing/quick"
+)
+
+func TestGetNodeProperty(outer *testing.T) {
+	check := func(key string, value int) bool {
+		entity := neo4j.Node{Props: singleProp(key, value)}
+
+		validValue, noErr := neo4j.GetNodeProperty[int](entity, key)
+		_, err := neo4j.GetNodeProperty[string](entity, key)
+
+		return validValue == value && noErr == nil && err != nil
+	}
+	if err := quick.Check(check, nil); err != nil {
+		outer.Error(err)
+	}
+}
+
+func TestGetRelationshipProperty(outer *testing.T) {
+	check := func(key string, value string) bool {
+		entity := neo4j.Relationship{Props: singleProp(key, value)}
+
+		validValue, noErr := neo4j.GetRelationshipProperty[string](entity, key)
+		_, err := neo4j.GetRelationshipProperty[int64](entity, key)
+
+		return validValue == value && noErr == nil && err != nil
+	}
+	if err := quick.Check(check, nil); err != nil {
+		outer.Error(err)
+	}
+}
+
+func singleProp[T any](key string, value T) map[string]any {
+	return map[string]any{key: value}
+}