如何在Python中计算JSON数据里的duration总时长

我有一个结构固定但内部值动态的JSON数据，需要在Python中计算所有"duration"字段的总时长。目前通过多层嵌套for循环实现，但希望找到更简洁、通用的高效方法。以下是JSON示例及现有代码：

JSON示例 #

{"data": {"9": {"mp_e_b": {"english": {"english_literature": {"video_lessons": {"The Fun They Had": {"-NNH9_LnN_RBLjxN3lKN": {"class_name": "9","duration": "28","subject_name": "English Literature"},"-NNH9jblawQprJ9-ZFmw": {"class_name": "9","duration": "25","subject_name": "English Literature"}}}},"hindi_grammar": {"video_lessons": {"हिंदी भाषा": {"-NNHA6axQjjM991cPvW_": {"class_name": "9","duration": "76","subject_name": "हिन्दी व्याकरण"}}}},"history": {"video_lessons": {"The French Revolution": {"-NNHAM0yNF4YcoQSTBRf": {"class_name": "9","duration": "56","subject_name": "History"}}}},"science": {"video_lessons": {"Matter in Our Surroundings": {"-NNHAC_cPxJTZ5iQYj3k": {"class_name": "9","duration": "5","subject_name": "Science"},"-NNHAFNjXkIJjLMuWmQU": {"class_name": "9","duration": "3","subject_name": "Science"}}}}},"hindi": {"computers": {"video_lessons": {"जावास्क्रिप्ट के प्रयोग से क्लाइंट की ओर से स्क्रिप्टिंग": {"-NNHAnYUZNVek70Amlbb": {"class_name": "9","duration": "20","subject_name": "Computers"}}}},"english_literature": {"video_lessons": {"The Fun They Had": {"-NO5EMyVA3PgaxoeYzbQ": {"class_name": "9","duration": "49","subject_name": "English Literature"}}}}}}}}}

现有嵌套循环实现 #

def reports_data():
    a = input("Enter the UID for the total reports: ")
    # userclass = input("Enter which class data you want to see or write 'all': ")
    total_time = []
    users = db.child("reports").child("app_reports").child(a).child("data").get()
    for i in users.each():
        # user_class = (i.key())
        var_class = (i.val()) #json of the class is being stored in the var variable
        for x, y in var_class.items():
                var_board = (y) #json of the board is being stored in the var variable
                for q, w in var_board.items():
                    var_lang = (w) #json of the language is being stored in the var variable
                    for e, r in var_lang.items():
                        var_subject = (r) #json of the subject is being stored in the var variable
                        for t, s in var_subject.items():
                            var_mode = (s) #json of the subject is being stored in the var variable
                            for u, o in var_mode.items():
                                var_chap = (o) #json of the type is being stored in the var variable
                                for a, p in var_chap.items():
                                    var_mode = (p) #json of the mode is being stored in the var variable
                                    for d, f in var_mode.items():
                                    #  outfile.write(f) #json of the perticular item watched is being stored in the var variable                                                
                                        if d == 'duration':
                                            total_time.append(f)
    total = sum(int(time) for time in total_time)
    print("Total time:", total,"sec")

更高效通用的解决方案 #

现有方法的问题是硬编码了嵌套层数，一旦JSON结构发生微小变化（比如新增/减少一层嵌套），代码就会失效。推荐使用递归遍历或迭代式遍历的方式，实现通用的字段收集逻辑：

方法1：递归生成器（简洁易读） #

通过递归遍历所有嵌套的字典和数组，自动收集所有duration字段的值：

def collect_durations(data):
    # 处理字典类型
    if isinstance(data, dict):
        for key, value in data.items():
            if key == "duration":
                yield int(value)  # 直接转成整数，避免后续重复转换
            else:
                # 递归遍历子节点
                yield from collect_durations(value)
    # 处理数组类型（如果JSON中存在数组结构，兼容扩展）
    elif isinstance(data, list):
        for item in data:
            yield from collect_durations(item)

def reports_data():
    a = input("Enter the UID for the total reports: ")
    users = db.child("reports").child("app_reports").child(a).child("data").get()
    # 将Firebase返回的对象转为字典
    data_dict = users.val()
    # 直接对生成器求和，内存效率更高
    total = sum(collect_durations(data_dict))
    print(f"Total time: {total} sec")

方法2：迭代式遍历（避免递归深度限制） #

如果JSON嵌套极深（超过Python默认递归深度限制），可以用栈实现迭代式遍历，避免栈溢出：

def collect_durations_iterative(data):
    stack = [data]
    while stack:
        current = stack.pop()
        if isinstance(current, dict):
            for key, value in current.items():
                if key == "duration":
                    yield int(value)
                else:
                    stack.append(value)
        elif isinstance(current, list):
            for item in current:
                stack.append(item)

def reports_data():
    a = input("Enter the UID for the total reports: ")
    users = db.child("reports").child("app_reports").child(a).child("data").get()
    data_dict = users.val()
    total = sum(collect_durations_iterative(data_dict))
    print(f"Total time: {total} sec")

方案优势 #

• 通用性强：无需依赖固定的嵌套层数，自动适配任何深度的JSON结构
• 代码简洁：相比多层嵌套循环，可读性和可维护性大幅提升
• 内存高效：使用生成器yield，无需先将所有duration存入列表，直接边遍历边累加，节省内存

内容的提问来源于stack exchange，提问作者Partik Chandra