Consider a sample JSON Document:

 {
 "store": {
 "book": [{
 "category": "reference",
 "author": "Nigel Rees",
 "title": "Sayings of the Century",
 "price": 8.95
 },
 {
 "category": "fiction",
 "author": "Evelyn Waugh",
 "title": "Sword of Honour",
 "price": 12.99
 },
 {
 "category": "fiction",
 "author": "Herman Melville",
 "title": "Moby Dick",
 "isbn": "0-553-21311-3",
 "price": 8.99
 },
 {
 "category": "fiction",
 "author": "J. R. R. Tolkien",
 "title": "The Lord of the Rings",
 "isbn": "0-395-19395-8",
 "price": 22.99
 }],
 "bicycle": {
 "color": "red",
 "price": 19.95
 }
 }
}

Issue:
When using a filter operation with @property , JSONPath Plus incorrectly excludes array elements whose property (array index) is 0, because in JavaScript if(0) means it returns false.

Example JSONPath expression:

$.store.bicycle[?(@property)]

Output

red,
19.95

This works correctly because the children have string keys ("color" , "price"), which are truthy. Since each child has a property key , the filter operation for @property evaluate to true ,and therefore all child nodes are included.

But,

$.store.book[?(@property)]

Here, book is an array and then the @property for the array elements are going to be the array indices.

• For the first element , @property is 0 (its array index)
• For the second element, @property is 1 and so on.

But, here the problem is since for the first element array index is 0 , @property = 0, JavaScript evaluates if(0) as false. So, the first book element is incorrectly excluded. Only array elements at index 1,2,3 appear, because their properties are 1, 2, 3 , which are truthy. But the first array element should also be included since it also has a property.

JSONPath Expression

$.store.book[?(@property)]

Actual Output : Output lists except the first array element

 {
 "category": "fiction",
 "author": "Evelyn Waugh",
 "title": "Sword of Honour",
 "price": 12.99
 },
 {
 "category": "fiction",
 "author": "Herman Melville",
 "title": "Moby Dick",
 "isbn": "0-553-21311-3",
 "price": 8.99
 },
 {
 "category": "fiction",
 "author": "J. R. R. Tolkien",
 "title": "The Lord of the Rings",
 "isbn": "0-395-19395-8",
 "price": 22.99
 }

Expected Output : Output should list all array elements
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}

Environment
- JSONPath-Plus version: jsonpath-plus@10.3.0
Desktop
 - OS: Ubuntu (Linux)
 - Node Version: v18.13.0