Question 110840 in Json Question posted in
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Parsing nested JSON and collecting data in a list

I am trying to parse a nested JSON and trying to collect data into a list under some condition.

Input JSON as below:

[
    {
        "name": "Thomas",
        "place": "USA",  
        "items": [
            {"item_name":"This is a book shelf", "level":1},
            {"item_name":"Introduction", "level":1},
            {"item_name":"parts", "level":2},   
            {"item_name":"market place", "level":3},
            {"item_name":"books", "level":1},
            {"item_name":"pens", "level":1},
            {"item_name":"pencils", "level":1}
        ],
        "descriptions": [
            {"item_name": "Books"}  
        ]
    },
    {
        "name": "Samy",
        "place": "UK",  
        "items": [
            {"item_name":"This is a cat house", "level":1},
            {"item_name":"Introduction", "level":1},
            {"item_name":"dog house", "level":3},   
            {"item_name":"cat house", "level":1},
            {"item_name":"cat food", "level":2},
            {"item_name":"cat name", "level":1},
            {"item_name":"Samy", "level":2}
        ],
        "descriptions": [
            {"item_name": "cat"}    
        ]
    }

]

I am reading json as below:

with open('test.json', 'r', encoding='utf8') as fp:
    data = json.load(fp)
for i in data:
   if i['name'] == "Thomas":
      #collect "item_name", values in a list (my_list) if "level":1
      #my_list = []

Expected output:

my_list = ["This is a book shelf", "Introduction", "books", "pens", "pencils"]

Since it’s a nested complex JSON, I am not able to collect the data into a list as I mentioned above. Please let me know no how to collect the data from the nested JSON.

Tags:

2

Answers


  1. 0

    Try:

    import json

with open("test.json", "r", encoding="utf8") as fp:
    data = json.load(fp)

my_list = [
    i["item_name"]
    for d in data
    for i in d["items"]
    if d["name"] == "Thomas" and i["level"] == 1
]
print(my_list)

    This prints:

    ['This is a book shelf', 'Introduction', 'books', 'pens', 'pencils']

    Or without list comprehension:

    my_list = []
for d in data:
    if d["name"] != "Thomas":
        continue
    for i in d["items"]:
        if i["level"] == 1:
            my_list.append(i["item_name"])

print(my_list)
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  2. 0

    Once we have the data we iterate over the outermost list of objects.
    We check if the object has the name equals to "Thomas" if true then we apply filter method with a lambda function on items list with a condition of level == 1

    This gives us a list of item objects who have level = 1

    In order to extract the item_name we use a comprehension so the final value in the final_list will be as you have expected.

    ["This is a book shelf", "Introduction", "books", "pens", "pencils"]

    import json
def get_final_list():
    with open('test.json', 'r', encoding='utf8') as fp:
        data = json.load(fp)

    final_list = []

    for obj in data:
        if obj.get("name") == "Thomas":
            x = list(filter(lambda item: item['level'] == 1, obj.get("items")))
            final_list = final_list + x

    final_list = [i.get("item_name") for i in final_list]

    return final_list
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