如何使用 Python 从 List 中提取值？

Question

I requested a JSON File from API. Then I want to parse/save just some values out of the File.

Code:

First the request call:

request = requests.get(self.url, verify = False)
request_data = request.json()

Example File (Type <class 'list'>):

[
    {
        "id1": null,
        "id2": "test1",
        "id3": "test2",
    }
    {
        "id1": null,
        "id2": "test3",
        "id3": "test4",
    }
]

Now I just want to get all id2 and their value, I tried with the code below, but it only works with dictionaries, how can I convert the list to a dictionary? Or can I extract the values with a list too?

value = {}
output_data = {}
value["id2"] = data.get("id2")
output_data.append(value)

Answer 1

You can do as below:

var = [
    {
        "id1": "null",
        "id2": "test1",
        "id3": "test2",
    },
    {
        "id1": "",
        "id2": "test3",
        "id3": "test4",
    }
]
output = []
for i in var:
    output.append(i['id2'])

print(output)

Answer 2

It looks like you have a list of dictionaries. One Pythonic way of dealing with this would be:

all_id2s = [entry['id2'] for entry in request_data]

This would create an array containing just the "id2" elements, like:

['test1', 'test3']

Check it out on IDEOne: https://ideone.com/5iVZhw