objectpath json query to get array values in python

Question

I've got some JSON like the following:

{
"books": [
    {
        "name": "Matthew"
    },
    {
        "name": "Mark",
        "sections": [
            {
                "reference": "1:1-1:8",
                "tags": [
                    "a",
                    "b"
                ],
                "summary": "blah",
                "notes": ""
            },
            {
                "reference": "1:9-1:15",
                "tags": [
                    "b",
                    "c",
                    "d"
                ],
                "summary": "",
                "notes": ""
            }
        ]
    }
]

}

I want to get a list of all sections using objectpath.

I've tried:

sections = Tree(db).execute('$.books[@.name is "Mark"].sections')
for section in sections:
    print(section)
    print("----\n")

but what is returned is a single section, which is an array. That is sections only has a single result while I am expecting (or at least wanting) just the array of 'sections'. This would save me having a for loop in a for loop.

Is there some special syntax to make it return how I want?

I've also tried:

'$.books[@.name is "Mark"].sections.*'
'$.books[@.name is "Mark"].sections[*]'

with no luck.

What's wrong with the python json library? [book['sections'] for book in json.loads(json_obj)['books']] — FHTMitchell
– FHTMitchell, Commented Aug 7, 2018 at 13:06
I"m using objectpath to help divorce the data structure from the code, so want to keep just a few strings in objectcode makes changing data layout very easy. — SupaGu
– SupaGu, Commented Aug 8, 2018 at 2:12

nio · Accepted Answer · 2018-08-07 13:34:21Z

2

sections is a generator object. To get the first item from it you can use next() function:

sections = Tree(db).execute('$.books[@.name is "Mark"].sections')
print(sections) # will show that it's a generator
for section in next(sections):
    print(section)
    print("----\n")

This first item will be the list with individual sections. Now you can iterate over each section using for loop.

edited Aug 7, 2018 at 13:34

answered Aug 7, 2018 at 13:23

nio

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1 Comment

philomath Over a year ago

This example helped me to extract a value from a nested json perfectly. Thanks

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