fix issue 654 by adding a new option FILTER_AS_ARRAY.

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

@@ -83,6 +83,47 @@ public enum Option {
      * If REQUIRE_PROPERTIES option is present PathNotFoundException is thrown.
      * If REQUIRE_PROPERTIES option is not present ["b-val"] is returned.
      */
-    REQUIRE_PROPERTIES
+    REQUIRE_PROPERTIES,
+
+    /**
+     * This mode can be used query at special filters.
+     * In the origin design, the filter receive an array and return an array.
+     * However, the subsequent operation will apply on each element in the returned array, rather than the whole array itself.
+     * The mode treats the result of filter as array, and it might be useful to some situation.
+     * For example:
+     *
+     * Given:
+     * <pre>
+     * [
+     *      {
+     *          "price" : 20,
+     *          "name" : "book1"
+     *      },
+     *      {
+     *          "price" : 30,
+     *          "name" : "book1"
+     *      },
+     *      {
+     *          "price" : 40,
+     *          "name" : "book1"
+     *      },
+     *      {
+     *          "price" : 50,
+     *          "name" : "book1"
+     *      },
+     * ]
+     * </pre>
+     *
+     * We want to get the first book which price is greater than 25.
+     *
+     * evaluating the path "$[?(@.price > 25)][0]"
+     *
+     * when using classic mode, the result will be null.
+     * when using this mode, the result will be [{"price":30,"name":"book1"}]. That is what we expected.
+     *
+     *
+     * Notice: When using this mode, the path of the result will be incorrect. Besides, SET operation will don't work.
+     */
+    FILTER_AS_ARRAY
 
 }

json-path/src/main/java/com/jayway/jsonpath/internal/path/PathToken.java

@@ -146,6 +146,20 @@ public abstract class PathToken {
         }
     }
 
+    protected void handleWholeArray(String currentPath, Object model, EvaluationContextImpl ctx){
+        // using FILTER_AS_ARRAY mode, details at com/jayway/jsonpath/Option.FILTER_AS_ARRAY
+        // NOTICE: When using this mode, the path of the result will be incorrect. Besides, SET operation will don't work.
+        if(isLeaf()){
+            Iterable<?> it = ctx.jsonProvider().toIterable(model);
+            for(Object object : it){
+                ctx.addResult(currentPath, PathRef.NO_OP, object);  // Use PathRef.NO_OP because the SET operation is banned.
+            }
+        }
+        else{
+            next().evaluate(currentPath, PathRef.NO_OP, model, ctx);
+        }
+    }
+
     PathToken prev(){
         return prev;
     }

json-path/src/main/java/com/jayway/jsonpath/internal/path/PredicatePathToken.java

@@ -16,11 +16,13 @@ package com.jayway.jsonpath.internal.path;
 
 import com.jayway.jsonpath.Configuration;
 import com.jayway.jsonpath.InvalidPathException;
+import com.jayway.jsonpath.Option;
 import com.jayway.jsonpath.Predicate;
 import com.jayway.jsonpath.internal.PathRef;
 
 import java.util.Collection;
 import java.util.Collections;
+import java.util.List;
 
 import static java.lang.String.format;
 import static java.util.Arrays.asList;
@@ -53,6 +55,17 @@ public class PredicatePathToken extends PathToken {
                 }
             }
         } else if (ctx.jsonProvider().isArray(model)){
+            if (ctx.configuration().containsOption(Option.FILTER_AS_ARRAY)){
+                //using FILTER_AS_ARRAY mode, details at com/jayway/jsonpath/Option.FILTER_AS_ARRAY
+                Iterable<?> objects = ctx.jsonProvider().toIterable(model);
+                Object filteredModel = ctx.jsonProvider().createArray();
+                for(Object idxModel : objects){
+                    if(accept(idxModel, ctx.rootDocument(), ctx.configuration(), ctx)){
+                        ((List)filteredModel).add(idxModel);
+                    }
+                }
+                handleWholeArray(currentPath, filteredModel, ctx);
+            } else {
                 int idx = 0;
                 Iterable<?> objects = ctx.jsonProvider().toIterable(model);
 
@@ -62,6 +75,7 @@ public class PredicatePathToken extends PathToken {
                     }
                     idx++;
                 }
+            }
         } else {
             if (isUpstreamDefinite()) {
                 throw new InvalidPathException(format("Filter: %s can not be applied to primitives. Current context is: %s", toString(), model));

json-path/src/test/java/com/jayway/jsonpath/Issue_654.java

@@ -0,0 +1,38 @@
+package com.jayway.jsonpath;
+
+
+import org.junit.Test;
+
+public class Issue_654 {
+
+    public static final Configuration conf = Configuration.builder().options(Option.FILTER_AS_ARRAY).build();
+
+    public static final String json = "[\n" +
+            "    [0, 1, 2], \n" +
+            "    [3, 4, 5],\n" +
+            "    [6, 7, 8],\n" +
+            "    [9, 10, 11],\n" +
+            "    [12, 13, 14]\n" +
+            "]";
+
+
+    @Test
+    public void test_1(){
+        // find the first array that its first element is greater than 4
+        Object res_ori = JsonPath.parse(json).read("$[?(@[0] > 4)][0]");
+        Object res_new = JsonPath.using(conf).parse(json).read("$[?(@[0] > 4)][0]");
+        assert (res_ori.toString().equals("[6,9,12]")); // origin mode will use INDEX_AT(0) operation on [6, 7, 8], [9, 10, 11], [12, 13, 14] respectively;
+        assert (res_new.toString().equals("[[6,7,8]]")); // new mode use INDEX_AT(0) operation on ([6, 7, 8], [9, 10, 11], [12, 13, 14])
+    }
+
+    @Test
+    public void test_2(){
+        // find the count of the elements whose first element is greater than 4
+        Object res_ori = JsonPath.parse(json).read("$[?(@[0] > 4)].length()");
+        Object res_new = JsonPath.using(conf).parse(json).read("$[?(@[0] > 4)].length()");
+        assert (res_ori.toString().equals("[3,3,3]")); // origin mode will use length() function on [6, 7, 8], [9, 10, 11], [12, 13, 14] respectively;
+        assert (res_new.toString().equals("[3]")); // new mode use length() function on ([6, 7, 8], [9, 10, 11], [12, 13, 14])
+    }
+
+
+}