#289 - Add support for Criteria composition.

We now support composition of Criteria objects to create a Criteria from one or more top-level criteria and to compose nested AND/OR Criteria objects:

Criteria.where("name").is("Foo")).and(Criteria.where("name").is("Bar").or("age")
				.lessThan(49).or(Criteria.where("name").not("Bar").and("age").greaterThan(49))

Original pull request: #307.

Author: mp911de

Diff for: src/main/java/org/springframework/data/r2dbc/core/DefaultStatementMapper.java

@@ -88,7 +88,7 @@ private PreparedOperation<Select> getMappedObject(SelectSpec selectSpec,
 		BindMarkers bindMarkers = this.dialect.getBindMarkersFactory().create();
 		Bindings bindings = Bindings.empty();
 
-		if (selectSpec.getCriteria() != null) {
+		if (!selectSpec.getCriteria().isEmpty()) {
 
 			BoundCondition mappedObject = this.updateMapper.getMappedObject(bindMarkers, selectSpec.getCriteria(), table,
 					entity);
@@ -203,7 +203,7 @@ private PreparedOperation<Update> getMappedObject(UpdateSpec updateSpec,
 
 		Update update;
 
-		if (updateSpec.getCriteria() != null) {
+		if (!updateSpec.getCriteria().isEmpty()) {
 
 			BoundCondition boundCondition = this.updateMapper.getMappedObject(bindMarkers, updateSpec.getCriteria(), table,
 					entity);
@@ -237,7 +237,7 @@ private PreparedOperation<Delete> getMappedObject(DeleteSpec deleteSpec,
 		Bindings bindings = Bindings.empty();
 
 		Delete delete;
-		if (deleteSpec.getCriteria() != null) {
+		if (!deleteSpec.getCriteria().isEmpty()) {
 
 			BoundCondition boundCondition = this.updateMapper.getMappedObject(bindMarkers, deleteSpec.getCriteria(), table,
 					entity);

Diff for: src/main/java/org/springframework/data/r2dbc/core/StatementMapper.java

@@ -185,7 +185,7 @@ class SelectSpec {
 		private final Table table;
 		private final List<String> projectedFields;
 		private final List<Expression> selectList;
-		private final @Nullable Criteria criteria;
+		private final Criteria criteria;
 		private final Sort sort;
 		private final long offset;
 		private final int limit;
@@ -219,7 +219,7 @@ public static SelectSpec create(String table) {
 		 * @since 1.1
 		 */
 		public static SelectSpec create(SqlIdentifier table) {
-			return new SelectSpec(Table.create(table), Collections.emptyList(), Collections.emptyList(), null,
+			return new SelectSpec(Table.create(table), Collections.emptyList(), Collections.emptyList(), Criteria.empty(),
 					Sort.unsorted(), -1, -1);
 		}
 
@@ -463,9 +463,9 @@ class UpdateSpec {
 		@Nullable
 		private final Update update;
 
-		private final @Nullable Criteria criteria;
+		private final Criteria criteria;
 
-		protected UpdateSpec(SqlIdentifier table, @Nullable Update update, @Nullable Criteria criteria) {
+		protected UpdateSpec(SqlIdentifier table, @Nullable Update update, Criteria criteria) {
 
 			this.table = table;
 			this.update = update;
@@ -490,7 +490,7 @@ public static UpdateSpec create(String table, Update update) {
 		 * @since 1.1
 		 */
 		public static UpdateSpec create(SqlIdentifier table, Update update) {
-			return new UpdateSpec(table, update, null);
+			return new UpdateSpec(table, update, Criteria.empty());
 		}
 
 		/**
@@ -512,7 +512,6 @@ public Update getUpdate() {
 			return this.update;
 		}
 
-		@Nullable
 		public Criteria getCriteria() {
 			return this.criteria;
 		}
@@ -525,9 +524,9 @@ class DeleteSpec {
 
 		private final SqlIdentifier table;
 
-		private final @Nullable Criteria criteria;
+		private final Criteria criteria;
 
-		protected DeleteSpec(SqlIdentifier table, @Nullable Criteria criteria) {
+		protected DeleteSpec(SqlIdentifier table, Criteria criteria) {
 			this.table = table;
 			this.criteria = criteria;
 		}
@@ -550,7 +549,7 @@ public static DeleteSpec create(String table) {
 		 * @since 1.1
 		 */
 		public static DeleteSpec create(SqlIdentifier table) {
-			return new DeleteSpec(table, null);
+			return new DeleteSpec(table, Criteria.empty());
 		}
 
 		/**
@@ -567,7 +566,6 @@ public SqlIdentifier getTable() {
 			return this.table;
 		}
 
-		@Nullable
 		public Criteria getCriteria() {
 			return this.criteria;
 		}