GH-157 - Provide a method to turn a Java map into an expression.

This closes #157.

neo4j-cypher-dsl-examples/src/test/java/org/neo4j/cypherdsl/examples/core/PropertiesTest.java

@@ -20,6 +20,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+import java.util.Map;
 import java.util.regex.Pattern;
 
 import org.assertj.core.api.Assertions;
@@ -102,4 +103,16 @@ void nestedProperties() {
 			.isEqualTo("MATCH (p:`Person`) WHERE p.`home.location`.y > 50 RETURN p.`home.location`.y");
 		// end::nested-properties[]
 	}
+
+	@Test
+	void usingExistingJavaMaps() {
+
+		var node = Cypher
+			.node("ANode")
+			.named("n")
+			.withProperties(Map.of("aProperty", 23));
+
+		assertThat(Cypher.match(node).returning(node).build().getCypher())
+			.isEqualTo("MATCH (n:`ANode` {aProperty: 23}) RETURN n");
+	}
 }

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/Cypher.java

@@ -22,6 +22,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 
 import org.apiguardian.api.API;
 import org.neo4j.cypherdsl.core.ListComprehension.OngoingDefinitionWithVariable;
@@ -393,6 +394,17 @@ public static MapExpression mapOf(Object... keysAndValues) {
 		return MapExpression.create(keysAndValues);
 	}
 
+	/**
+	 * Creates a map of expression from a Java Map.
+	 *
+	 * @param map A map to be turned into a MapExpression
+	 * @return A new map expression.
+	 */
+	public static MapExpression asExpression(Map<String, Object> map) {
+
+		return MapExpression.create(map);
+	}
+
 	/**
 	 * Creates a {@link ListExpression list-expression} from several expressions.
 	 *

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/ExposesProperties.java

@@ -18,6 +18,8 @@
  */
 package org.neo4j.cypherdsl.core;
 
+import java.util.Map;
+
 /**
  * A container that exposes methods to add properties with values to nodes or relationships.
  *
@@ -45,4 +47,15 @@ public interface ExposesProperties<T extends ExposesProperties<?> & PropertyCont
 	 * @return The new property container.
 	 */
 	T withProperties(Object... keysAndValues);
+
+	/**
+	 * Creates a a copy of this property container with additional properties.
+	 *
+	 * @param newProperties A map with the new properties
+	 * @return The new property container.
+	 */
+	default T withProperties(Map<String, Object> newProperties) {
+
+		return withProperties(MapExpression.create(newProperties));
+	}
 }

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/MapExpression.java

@@ -23,6 +23,7 @@
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 import org.apiguardian.api.API;
@@ -43,6 +44,18 @@
 @API(status = INTERNAL, since = "1.0")
 public final class MapExpression extends TypedSubtree<Expression> implements Expression {
 
+	static MapExpression create(Map<String, Object> map) {
+
+		Object[] args = new Object[map.size() * 2];
+		int i = 0;
+		for (Map.Entry<String, Object> entry : map.entrySet()) {
+			Object value = entry.getValue();
+			args[i++] = entry.getKey();
+			args[i++] = value instanceof Expression ? value : Cypher.literalOf(value);
+		}
+		return create(args);
+	}
+
 	static MapExpression create(Object... input) {
 
 		Assertions.isTrue(input.length % 2 == 0, "Need an even number of input parameters");

neo4j-cypher-dsl/src/test/java/org/neo4j/cypherdsl/core/CypherIT.java

@@ -21,6 +21,8 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
+import java.util.LinkedHashMap;
+import java.util.Map;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
@@ -2701,6 +2703,23 @@ void shouldRenderPointFunction() {
 	@Nested
 	class PropertyRendering {
 
+		@Test // GH-157
+		void usingExistingJavaMaps() {
+
+			Map<String, Object> newProperties = new LinkedHashMap<>();
+			newProperties.put("prop1", 23);
+			newProperties.put("theTruth", 42);
+			newProperties.put("somethingElse", "foobar");
+			newProperties.put("aParam", Cypher.parameter("x").withValue("y"));
+			Node node = Cypher
+				.node("ANode")
+				.named("n")
+				.withProperties(newProperties);
+
+			assertThat(Cypher.match(node).returning(node).build().getCypher())
+				.isEqualTo("MATCH (n:`ANode` {prop1: 23, theTruth: 42, somethingElse: 'foobar', aParam: $x}) RETURN n");
+		}
+
 		@Test // GH-114
 		void manuallyNested() {
 			Node node = Cypher.node("Person").named("p");