Question

我有一个选项卡式窗口，要求用户输入一些数据，然后按一个按钮，该按钮既可以更新列表视图，又可以将新数据追加到JSON文件的末尾，但是我似乎无法弄清楚将数据附加在方括号[]中以使其有效为JSON，所以我想要的是：

[
    {
        "store": "My Store",
        "address": "123 Anywhere Calgary, Ab",
        "category": "Grocery",
        "item": "Ground Coffee",
        "qty": "1",
        "price": "10.99",
        "GST": false,
        "PST": false,
        "EHC": "0.",
        "deposit": "0.",
        "other": "0."
    },
    {
        "store": "My Store",
        "address": "123 Anywhere Calgary, Ab",
        "category": "Grocery",
        "item": "Flour, All Purp",
        "qty": "1",
        "price": "9.99",
        "GST": false,
        "PST": false,
        "EHC": "0.",
        "deposit": "0.",
        "other": "0."
    },
    {   
        "store": "My Store",
        "address": "123 Anywhere Calgary, Ab",
        "category": "Grocery",
        "item": "Taco Shells",
        "qty": "1",
        "price": "4.59",
        "GST": false,
        "PST": false,
        "EHC": "0.",
        "deposit": "0.",
        "other": "0."
    },
    {
        "store": "My Store",
        "address": "123 Anywhere Calgary, Ab",
        "category": "Grocery",
        "item": "BBQ Sauce",
        "qty": "1",
        "price": "3.79",
        "GST": false,
        "PST": false,
        "EHC": "0.",
        "deposit": "0.",
        "other": "0."
    },
    {
        "store": "My Store",
        "address": "123 Anywhere Calgary, Ab",
        "category": "Grocery",
        "item": "Ritz Bits",
        "qty": "1",
        "price": "3.49",
        "GST": false,
        "PST": false,
        "EHC": "0.",
        "deposit": "0.",
        "other": "0."
    }
]

哪个可以验证为正确的JSON格式，但是在附加到文件时得到的是：

[
    {
        "store": "My Store",
        "address": "123 Anywhere Calgary, Ab",
        "category": "Grocery",
        "item": "Ground Coffee",
        "qty": "1",
        "price": "10.99",
        "GST": false,
        "PST": false,
        "EHC": "0.",
        "deposit": "0.",
        "other": "0."
    }
]
[
    {
        "store": "My Store",
        "address": "123 Anywhere Calgary, Ab",
        "category": "Grocery",
        "item": "Flour, All Purp",
        "qty": "1",
        "price": "9.99",
        "GST": false,
        "PST": false,
        "EHC": "0.",
        "deposit": "0.",
        "other": "0."
    }
]

由于[]括号将每个附加项括起来，因此它不再是有效的JSON。那么，如何在[和]之间附加项目以保持JSON有效？有没有一种方法可以追加项目，然后转到文件的开头并插入[，然后移至文件的末尾并追加]？

问题是，从技术上来说，用户可以将杂货添加到JSON文件中，就像我在技术上使用JSON作为“数据库”一样。当用户运行该程序时，我希望能够重新读取JSON数据并使用以前的条目填充列表控件。

还是应该看看另一种存储数据的方法？

谢谢！

Answer 1

with open("my_file.json","rb") as f:
    existing = json.load(f)
existing.append(item)
with open("my_file.json","wb") as f:
    json.dump(existing,f)

或者更好地将其抽象出来

class JSONList(object):
     def __init__(self,fname):
        self.fname = fname
        self.items = []
        self.load()


     def save():
        with open(self.fname,"wb") as f:
            json.dump(self.items,f)

     def load(self):
        try:
            self.items = json.load(open(self.fname,"rb"))
        except: # bad form empty except... but whatever
            self.items = []

     def append(self,new_item,save=True):
        self.items.append(new_item)
        if save:
           self.save()

python并附加到JSON文件

1 个答案: