Fixes, disallow paths

Author: katcharov

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

@@ -17,6 +17,7 @@
 package com.mongodb.client.model.expressions;
 
 import org.bson.conversions.Bson;
+import org.bson.types.Decimal128;
 
 import java.time.Instant;
 
@@ -46,7 +47,11 @@ default BooleanExpression getBoolean(final String fieldName, final boolean other
 
     NumberExpression getNumber(String fieldName, NumberExpression other);
 
-    default NumberExpression getNumber(final String fieldName, final Number other) {
+    default NumberExpression getNumber(final String fieldName, final double other) {
+        return getNumber(fieldName, Expressions.numberToExpression(other));
+    }
+
+    default NumberExpression getNumber(final String fieldName, final Decimal128 other) {
         return getNumber(fieldName, Expressions.numberToExpression(other));
     }
 

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

@@ -139,10 +139,15 @@ public <R extends Expression> R cond(final R left, final R right) {
 
     /** @see DocumentExpression */
 
-    private Function<CodecRegistry, AstPlaceholder> getFieldInternal(final String fieldBoolean) {
-        return (cr) -> astDoc("$getField", new BsonDocument()
-                .append("input", this.fn.apply(cr).bsonValue)
-                .append("field", new BsonString(fieldBoolean)));
+    private Function<CodecRegistry, AstPlaceholder> getFieldInternal(final String fieldName) {
+        return (cr) -> {
+            BsonValue value = fieldName.startsWith("$")
+                    ? new BsonDocument("$literal", new BsonString(fieldName))
+                    : new BsonString(fieldName);
+            return astDoc("$getField", new BsonDocument()
+                    .append("input", this.fn.apply(cr).bsonValue)
+                    .append("field", value));
+        };
     }
 
     @Override
@@ -216,7 +221,7 @@ public <R extends Expression> ArrayExpression<R> getArray(final String fieldName
     }
 
     @Override
-    public <T1 extends Expression> ArrayExpression<T1> getArray(final String fieldName, final ArrayExpression<? extends T1> other) {
+    public <R extends Expression> ArrayExpression<R> getArray(final String fieldName, final ArrayExpression<? extends R> other) {
         return getArray(fieldName).isArrayOr(other);
     }
 

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

@@ -96,6 +96,16 @@ public void getFieldTest() {
                 .getDate("a").month(of("UTC")));
         assertExpression(3, ofDoc("{a: [3, 2]}").getArray("a").first());
         assertExpression(2, ofDoc("{a: {b: 2}}").getDocument("a").getInteger("b"));
+
+        // field names, not paths
+        DocumentExpression doc = ofDoc("{a: {b: 2}, 'a.b': 3, 'a$b': 4, '$a.b': 5}");
+        assertExpression(2, doc.getDocument("a").getInteger("b"));
+        assertExpression(3, doc.getInteger("a.b"));
+        assertExpression(4, doc.getInteger("a$b"));
+        assertExpression(5,
+                doc.getInteger("$a.b"),
+                "{'$getField': {'input': {'$literal': {'a': {'b': 2}, 'a.b': 3, 'a$b': 4, '$a.b': 5}}, "
+                        + "'field': {'$literal': '$a.b'}}}");
     }
 
     @Test