jayway jsonpath filter inner json array

Question

I have a JSON response which I was able to filter to a format like the one below using jayway jsonpath syntax:

[
   {
      "entityName" : "Financial Assets",
      "entityFullPath" : [
         "Path123",
         "Alternative"
      ]
   },
   {
      "entityName" : "123",
      "entityFullPath" : [
         "Path123",
         "Alternative"
      ]
   }
]

jsonpath:

$..domainEntity[?(@.dataObjectId !== null)].['entityName','entityFullPath']

What I want to do further, is to get only the first value from entityFullPath array - is that case Path123 , so the final JSON would look like this:

[
   {
      "entityName" : "Financial Assets",
      "entityFullPath" : [
         "Path123"
      ]
   },
   {
      "entityName" : "123",
      "entityFullPath" : [
         "Path123"
      ]
   }
]

Or even better (not sure if you can get rid of json array like that using only jsonpath):

[
   {
      "entityName" : "Financial Assets",
      "entityFullPath" : "Path123"
   },
   {
      "entityName" : "123",
      "entityFullPath" : "Path123"
     
   }
]

Is such drill down doable using only jsonpath? I'm using jayway flavor.

Answer 1

Unfortunately, this is not possible. Unlike XPath, JSONPath (as of now) offers no operations for accessing parent or sibling nodes from the given node. Furthermore, the [,] union operation (as commonly implemented) does not allow us to join nodes on different levels; that's why we are stuck here.

A not so elegant workaround that comes to mind is recreating the target JSON by merging the result of two (or more) individual JSONPath queries. Here is a JavaScript example of how this could look like:

 let json = [ { "entityName": "Financial Assets", "entityFullPath": [ "Path123", "Alternative" ] }, { "entityName": "123", "entityFullPath": [ "Path123", "Alternative" ] } ]; var a = JSONPath.JSONPath({path: '$.[*].entityName', json: json}); //= [ // "Financial Assets", // "123" //]; var b = JSONPath.JSONPath({path: '$.[*].entityFullPath.[0]', json: json}); //= [ // "Path123", // "Path123" //]; const result = Object.assign({}, [{"entityName":a[0], "extern_uid":b[0]}, {"entityName":a[1], "extern_uid":b[1]}]); console.log(result);

 <script src="https://cdn.jsdelivr.net/npm/jsonpath-plus@4.0.0/dist/index-umd.min.js"></script>

It's arguably best to work with the previous result and access the properties as needed in your regular code.