python - Use A Conditional Statement To Check If A JSON Key Exists - Python3 -

i able return value of key class every time rappers in json structure. did parse_classes function seen below.

how can make conditional statment (if, else, or maybe loop) check if key class exists in argument json_data. if exist (the "if") run block of code , if not exists (the "else") move on funcction.

here code:

def parse_classes(json_data):     lst = list() #list of values of key "class" found     classes in json_data['images'][0]['classifiers'][0]: #runs every time find "classes" exists in json data.         item in json_data['images'][0]['classifiers'][0]['classes']: #gets "classes" in json , puts item             lst.append(item['class') #adds key "class" "item" list "lst"      return(lst) #returns list "lst" 

here example json structure:

{"images": ["classifiers": ["classes": ["class": "street"]]]} 

thanks, brendan (python 3.6.1, windows 10 64bit)

i think mean if instead of for:

def parse_classes(json_data):     lst = set()     if 'classes' in json_data['images'][0]['classifiers'][0]:         item in json_data['images'][0]['classifiers'][0]['classes']:             lst.add(item['class'])     else:         print("")     return lst 

or defensively

def parse_classes(json_data):     lst = set()     if (json_data.get('images')             , json_data['images'][0].get('classifiers')             , json_data['images'][0]['classifiers'][0].get('classes')):         item in json_data['images'][0]['classifiers'][0].get('classes', []):             lst.add(item['class'])     return lst if lst else none 

if want class in classifiers in images

def parse_classes(json_data):     lst = set()     image in json_data.get('images', []):         classifier in image.get('classifiers', []):             item in classifier.get('classes', []):                 lst.add(item['class'])     return lst if lst else none