Add "has"

Author: katcharov

driver-core/src/main/com/mongodb/client/model/expressions/MapExpression.java

@@ -20,6 +20,12 @@
 
 public interface MapExpression<T extends Expression> extends Expression {
 
+    BooleanExpression has(StringExpression key);
+
+    default BooleanExpression has(String key) {
+        return has(of(key));
+    }
+
     // TODO-END doc "user asserts"
     T get(StringExpression key);
 

driver-core/src/main/com/mongodb/client/model/expressions/MqlExpression.java

@@ -777,6 +777,17 @@ public StringExpression substrBytes(final IntegerExpression start, final Integer
         return new MqlExpression<>(ast("$substrBytes", start, length));
     }
 
+    @Override
+    public BooleanExpression has(StringExpression key) {
+        return get(key).ne(ofRem());
+    }
+
+    static <R extends Expression> R ofRem() {
+        // $$REMOVE is intentionally not exposed to users
+        return new MqlExpression<>((cr) -> new MqlExpression.AstPlaceholder(new BsonString("$$REMOVE")))
+                .assertImplementsAllExpressions();
+    }
+
     /** @see MapExpression
      * @see EntryExpression */
 

driver-core/src/test/functional/com/mongodb/client/model/expressions/AbstractExpressionsFunctionalTest.java

@@ -126,11 +126,5 @@ public BsonValue readValue(final BsonReader reader, final DecoderContext decoder
         }
     }
 
-
-    static <R extends Expression> R ofRem() {
-        // $$REMOVE is intentionally not exposed to users
-        return new MqlExpression<>((cr) -> new MqlExpression.AstPlaceholder(new BsonString("$$REMOVE")))
-                .assertImplementsAllExpressions();
-    }
 }
 

driver-core/src/test/functional/com/mongodb/client/model/expressions/ComparisonExpressionsFunctionalTest.java

@@ -40,7 +40,7 @@ class ComparisonExpressionsFunctionalTest extends AbstractExpressionsFunctionalT
 
     // https://www.mongodb.com/docs/manual/reference/bson-type-comparison-order/#std-label-bson-types-comparison-order
     private final List<Expression> sampleValues = Arrays.asList(
-            ofRem(),
+            MqlExpression.ofRem(),
             ofNull(),
             of(0),
             of(1),

driver-core/src/test/functional/com/mongodb/client/model/expressions/MapExpressionsFunctionalTest.java

@@ -76,6 +76,18 @@ public void getSetMapTest() {
                 ofMap(Document.parse("{ 'null': null }")).get("null", of(1)));
     }
 
+    @Test
+    public void hasMapTest() {
+        assertExpression(
+                true,
+                mapKey123.has(of("key")),
+                "{'$ne': [{'$getField': {'input': {'$setField': {'field': 'key', 'input': " +
+                        "{'$literal': {}}, 'value': 123}}, 'field': 'key'}}, '$$REMOVE']}");
+        assertExpression(
+                false,
+                mapKey123.has("not_key"));
+    }
+
     @Test
     public void getSetEntryTest() {
         EntryExpression<IntegerExpression> entryA1 = ofEntry(of("keyA"), of(1));