Getting last element from a JSON with Python

Question

I have files with the following structure:

{
    "function": "ComAl_Set_nad_crtl_xcall_state",
    "timeStamp": 1488500329974,
    "Param1": "SIG_NAD_XCALL_ATTEMPTS_COUNT",
    "Value1": "2"
}

These JSON files are created by some functions which I have in my program. But I have an issue getting the last value from these files (Value1). Currently this is the code I am using to get data from the file:

def get_json_from_stub(self, file_name):
    def jsonize_stub(raw_data):
        end = raw_data.rfind(",")
        parsed_data = "[" + raw_data[:end] + "]" 
        return json.loads(parsed_data.replace("\00", ""))

    command = "'cat "  + self.stub_path + file_name + "'"
    content =  self.send_ssh_command(command)
    json_stub = jsonize_stub(content)
    return json_stub

and this is the code for getting Value1:

@app.route('/stub/comal/getSignal/ComAl_Set_nad_crtl_xcall_requests', methods=['GET'])
    def get_nad_crtl_xcall_requests():
        file_name = "ComAl_Set_nad_crtl_xcall_requests.out"
        json_stub = self.stubManager.get_json_from_stub(file_name)
        return MapEcallRequests().tech_to_business(json_stub[-1]["Value1"])

more specifically I want to replace json_stub[-1]["Value1"] with another way of getting Value1. The problem is that sometimes these files don´t get written so I would like to get Value1 in a different way and to raise an error message in case Value1 isn´t there, just to avoid my application crashing in case the value is not there. Is there are way to do it? Thanks.

Answer 1

You can check if the key exists (you can also check if the length is correct):

if len(json_stub) > 0 and json_stub[-1].get('Value1') is not None:
    value1_node = json_stub[-1]('Value1')
else:
    # 'Value1' key does not exist