Negate exist checks in inline filters (not defined or null)

parse(JSON_DOCUMENT).read("$.store.book[?(!@.isbn)]")

changelog.md

@@ -16,6 +16,8 @@ In The Pipe
 * Inline filter does not force path first  
   `parse(JSON_DOCUMENT).read("$.store.book[?(@.category == 'reference')].author")`    
   `parse(JSON_DOCUMENT).read("$.store.book[?('reference' == @.category)].author")`    
+* Negate exist checks in inline filters (not defined or null) 
+  `parse(JSON_DOCUMENT).read("$.store.book[?(!@.isbn)]")`    
 
 
 1.1.0 (2014-10-01)

json-path/src/main/java/com/jayway/jsonpath/Criteria.java

@@ -360,8 +360,13 @@ public class Criteria implements Predicate {
             boolean exists = ((Boolean) right);
             try {
                 Configuration c = Configuration.builder().jsonProvider(ctx.configuration().jsonProvider()).options(Option.REQUIRE_PROPERTIES).build();
-                ((Path)left).evaluate(ctx.item(), ctx.root(), c).getValue();
-                return exists;
+                Object value = ((Path) left).evaluate(ctx.item(), ctx.root(), c).getValue();
+                if(exists){
+                    return  (value != null);
+                } else {
+                    return (value == null);
+                }
+
             } catch (PathNotFoundException e) {
                 return !exists;
             }
@@ -654,7 +659,8 @@ public class Criteria implements Predicate {
     }
 
     private static boolean isPath(String string){
-       return (string != null && (string.startsWith("$") || string.startsWith("@")));
+       return (string != null
+               && (string.startsWith("$") || string.startsWith("@") || string.startsWith("!@")));
     }
 
     private static boolean isString(String string){
@@ -717,8 +723,13 @@ public class Criteria implements Predicate {
         Object rightPrepared = right;
         Path leftPath = null;
         Path rightPath = null;
+        boolean existsCheck = true;
 
         if(isPath(left)){
+            if(left.charAt(0) == '!'){
+                existsCheck = false;
+                left = left.substring(1);
+            }
             leftPath = PathCompiler.compile(left);
             if(!leftPath.isDefinite()){
                 throw new InvalidPathException("the predicate path: " + left + " is not definite");
@@ -731,6 +742,9 @@ public class Criteria implements Predicate {
         }
 
         if(isPath(right)){
+            if(right.charAt(0) == '!'){
+                throw new InvalidPathException("Invalid negation! Can only be used for existence check e.g [?(!@.foo)]");
+            }
             rightPath = PathCompiler.compile(right);
             if(!rightPath.isDefinite()){
                 throw new InvalidPathException("the predicate path: " + right + " is not definite");
@@ -743,7 +757,7 @@ public class Criteria implements Predicate {
         }
 
         if(leftPath != null && operator.isEmpty()){
-            return Criteria.where(leftPath).exists(true);
+            return Criteria.where(leftPath).exists(existsCheck);
         } else {
             return new Criteria(leftPrepared, CriteriaType.parse(operator), rightPrepared);
         }

json-path/src/test/java/com/jayway/jsonpath/InlineFilterTest.java

@@ -2,6 +2,7 @@ package com.jayway.jsonpath;
 
 import org.junit.Test;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import static java.util.Arrays.asList;
@@ -129,4 +130,31 @@ public class InlineFilterTest extends BaseTest {
         resLeft = JsonPath.parse(JSON_DOCUMENT).read("$.store.book[?(@.category =~ /REFERENCE/i)].author");
         assertThat(resLeft).containsExactly("Nigel Rees");
     }
+
+    @Test
+    public void negate_exists_check() {
+        List<String> hasIsbn = JsonPath.parse(JSON_DOCUMENT).read("$.store.book[?(@.isbn)].author");
+        assertThat(hasIsbn).containsExactly("Herman Melville", "J. R. R. Tolkien");
+
+        List<String> noIsbn = JsonPath.parse(JSON_DOCUMENT).read("$.store.book[?(!@.isbn)].author");
+
+        assertThat(noIsbn).containsExactly("Nigel Rees", "Evelyn Waugh");
+    }
+
+    @Test
+    public void negate_exists_check_primitive() {
+        List<Integer> ints = new ArrayList<Integer>();
+        ints.add(0);
+        ints.add(1);
+        ints.add(null);
+        ints.add(2);
+        ints.add(3);
+
+
+        List<Integer> notNull = JsonPath.parse(ints).read("$[?(@)]");
+        assertThat(notNull).containsExactly(0,1,2,3);
+
+        List<Integer> isNull = JsonPath.parse(ints).read("$[?(!@)]");
+        assertThat(isNull).containsExactly(new Integer[]{null});
+    }
 }

json-path/src/test/java/com/jayway/jsonpath/old/FilterTest.java

@@ -191,7 +191,6 @@ public class FilterTest extends BaseTest {
     }
 
     @Test
-    //@Ignore //TODO: finalize behaviour
     public void exists_filters_evaluates() throws Exception {
         Map<String, Object> check = new HashMap<String, Object>();
         check.put("foo", "foo");
@@ -200,8 +199,8 @@ public class FilterTest extends BaseTest {
         assertTrue(filter(where("foo").exists(true)).apply(createPredicateContext(check)));
         assertFalse(filter(where("foo").exists(false)).apply(createPredicateContext(check)));
 
-        assertTrue(filter(where("foo_null").exists(true)).apply(createPredicateContext(check)));
-        assertFalse(filter(where("foo_null").exists(false)).apply(createPredicateContext(check)));
+        assertTrue(filter(where("foo_null").exists(false)).apply(createPredicateContext(check)));
+        assertFalse(filter(where("foo_null").exists(true)).apply(createPredicateContext(check)));
 
         assertTrue(filter(where("bar").exists(false)).apply(createPredicateContext(check)));
         assertFalse(filter(where("bar").exists(true)).apply(createPredicateContext(check)));