Allow users to reuse nodes in CREATE clause

src/Patterns/Node.php

@@ -12,6 +12,7 @@
 
 use WikibaseSolutions\CypherDSL\Expressions\Label;
 use WikibaseSolutions\CypherDSL\Expressions\Literals\Map;
+use function WikibaseSolutions\CypherDSL\node;
 use WikibaseSolutions\CypherDSL\Traits\PatternTraits\PropertyPatternTrait;
 use WikibaseSolutions\CypherDSL\Utils\NameUtils;
 
@@ -77,6 +78,17 @@ public function getLabels(): array
         return $this->labels;
     }
 
+    /**
+     * Create a new node with the same variable as this node. Useful for using nodes
+     * inside a CREATE clause that were previously matched on in a MATCH clause.
+     *
+     * @see https://github.com/neo4j-php/php-cypher-dsl/issues/96
+     */
+    public function variable(): self
+    {
+        return node()->withVariable($this->getVariable());
+    }
+
     /**
      * Returns a label with the variable in this node.
      *

tests/end-to-end/ExamplesTest.php

@@ -227,6 +227,21 @@ public function testMatchClauseExample1(): void
         $this->assertStringMatchesFormat("MATCH (%s) RETURN %s", $query);
     }
 
+    public function testCreateReuseVariable(): void
+    {
+        $charlie = node("Person")->withProperties(["name" => "Charlie Sheen"]);
+        $oliver = node("Person")->withProperties(["name" => "Oliver Stone"]);
+
+        $wallStreet = node("Movie")->withProperties(["title" => "Wall Street"]);
+
+        $query = query()
+            ->match([$charlie, $oliver])
+            ->create($charlie->variable()->relationshipTo($wallStreet, type: "ACTED_IN", properties: ["role" => "Bud Fox"])->relationshipFrom($oliver->variable()))
+            ->build();
+
+        $this->assertStringMatchesFormat("MATCH (%s:Person {name: 'Charlie Sheen'}), (%s:Person {name: 'Oliver Stone'}) CREATE (%s)-[:ACTED_IN {role: 'Bud Fox'}]->(:Movie {title: 'Wall Street'})<--(%s)", $query);
+    }
+
     public function testMatchClauseExample2(): void
     {
         $movie = node("Movie");

tests/unit/Patterns/NodeTest.php

@@ -325,4 +325,36 @@ public function testLabeledMultipleLabels(): void
 
         $this->assertEquals(new Label($node->getVariable(), 'German', 'Swedish'), $labeled);
     }
+
+    public function testVariableNewNode(): void
+    {
+        $node = new Node();
+        $variable = $node->variable();
+
+        $this->assertMatchesRegularExpression('/^\(var\w{8}\)$/', $variable->toQuery());
+    }
+
+    public function testVariableNodeWithProperties(): void
+    {
+        $node = new Node();
+        $node->withProperties(['a' => 1, 'b' => 2, 'c' => 3]);
+
+        $this->assertStringMatchesFormat('({a: 1, b: 2, c: 3})', $node->toQuery());
+
+        $variable = $node->variable();
+
+        $this->assertMatchesRegularExpression('/^\(var\w{8}\)$/', $variable->toQuery());
+    }
+
+    public function testVariableNodeWithExistingVariable(): void
+    {
+        $node = new Node();
+        $node->withVariable('foo');
+
+        $this->assertSame('(foo)', $node->toQuery());
+
+        $variable = $node->variable();
+
+        $this->assertSame('(foo)', $variable->toQuery());
+    }
 }