XPath to read array elements from JSON string

Question

I am having JSON output string in the following structure.

{
    "Results": [
        { "Result": 5756 },
        { "Result": 5234 },
        { "Result": 5432 }
    ]
}

From this, I want to access each element (one by one – 5756, 5234, 5432) of “Results” array.

In order to read/extract the element, I am using “XPath”. I have tried many XPaths, however got no luck thus far; following are few of them.

//*[1].Result -- Invalid xPath
//*[1].Result[0] -- Invalid xPath
//*[1]/Result[0] -- NULL
//*[1]/Result -- NULL

And when used //*[1] It gives entire JSON string as following.

[
    { "Result": 5756 },
    { "Result": 5234 },
    { "Result": 5432 }
]

Could you please help me out to resolve the problem I am facing? Or In case, structure of JSON is required to be changed, suggest me new structure along with XPath to access array element, example would be appreciated.

Many thanks in advance.

Call me crazy but isn't XPath limited to parsing XML documents? — Phil
– Phil, Commented Dec 10, 2013 at 5:45
You can use XPath to parse JSON also. goessner.net/articles/JsonPath check this. — CodeGuru
– CodeGuru, Commented Dec 10, 2013 at 5:48
I'm pretty sure you can't (happy to be proven wrong). If you're using JSONPath, please tag this question accordingly (ie remove the xpath tag) — Phil
– Phil, Commented Dec 10, 2013 at 6:06
What tool are you actually using to perform your extraction? — Louis
– Louis, Commented Dec 10, 2013 at 9:11

Michael Kruglos · Accepted Answer · 2013-12-11 07:38:41Z

2

Here's an example of how you can do it in Ruby, using jsonpath gem (http://rubygems.org/gems/jsonpath):

requre 'json'
require 'jsonpath'

# I initialize the data inline here, but you can read it from file
data = <<-EOS
{
  "Results": [
    { "Result": 5756 },
    { "Result": 5234 },
    { "Result": 5432 }
   ]
}
EOS

json_data = JSON.parse(data)

# First value:
JsonPath.new("$.Results[0].Result").on(json_data) # => 5756

# Second value:
JsonPath.new("$.Results[1].Result").on(json_data) # => 5234

# Third value:
JsonPath.new("$.Results[2].Result").on(json_data) # => 5432

answered Dec 11, 2013 at 7:38

Michael Kruglos

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Hakan Bilgin · Accepted Answer · 2014-01-03 11:46:46Z

@Popeye - I recently released a first version of a JS lib that does exactly what you're looking for; DefiantJS (http://defiantjs.com)

With this lib, you can query any JSON structure with fullscale XPath syntax. You can also use the XPath evaluator to test/verify XPath expressions instantly here:

http://www.defiantjs.com/#xpath_evaluator

As for your example, assuming your result data is as simple as you've examplified, I would suggest a JSON structure like this:

var res = {
    "Results": [
          5756,
          5234,
          5432
    ]
}

And using the XPath evaluator (and see the console on your browser for hints), you can extract the selections you want with this XPath:

var sel = Defiant.search(res, '//Results');
// sel contains the array -> [5276, 5234, 5432]

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