如何使用打字稿在 json 文件中附加数据？

Question

我在 .json 文件中附加数据时遇到问题。所以我搜索了这个问题，找到了很多结果，但对我不起作用。如果有一个库可以方便地在 json 文件中附加数据或修复我的代码，我将不胜感激

这是我的函数

function writeToJson(path: string, data: any, rewrite: boolean = false) 
{
    let old_data: any = fs.readFileSync(path)
    if(old_data.length == 0 || rewrite == true)
    {
        fs.writeFileSync(path, JSON.stringify(data, null, 4))
        return
    }
    let json_obj: any = [JSON.parse(old_data)] // without brackets it reverts an error
    json_obj.push(data)
    fs.writeFileSync(path, JSON.stringify(json_obj, null, 4))
}

下面是实际结果。json

[
    [
        [
            [
                [
                    {
                        "price": 0.5631746759368121,
                        "timestamp": "5/4/2022, 2:06:44 AM"
                    },
                    {
                        "price": 0.5631746759368121,
                        "timestamp": "5/4/2022, 2:06:53 AM"
                    }
                ],
                {
                    "price": 0.5631746759368121,
                    "timestamp": "5/4/2022, 2:06:55 AM"
                }
            ],
            {
                "price": 0.5631746759368121,
                "timestamp": "5/4/2022, 2:06:58 AM"
            }
        ],
        {
            "price": 0.5631746759368121,
            "timestamp": "5/4/2022, 2:07:01 AM"
        }
    ],
    {
        "price": 0.5631746759368121,
        "timestamp": "5/4/2022, 2:07:04 AM"
    }
]

因此我希望得到类似

的结果

{
   {
     "price": 0.5631746759368121,
     "timestamp": "5/4/2022, 2:07:04 AM"
   }
   {
     "price": 0.5631746759368121,
     "timestamp": "5/4/2022, 2:07:04 AM"
   }
   ...
   {
     "price": 0.5631746759368121,
     "timestamp": "5/4/2022, 2:07:04 AM"
   }
}

Answer 1

您可能只是错过了指定编码：

fs.readFileSync(path, "utf8")

Node.js doc of fs.readFileSync:

If the encoding option is specified then this function returns a string. Otherwise it returns a buffer.

所以现在您应该可以按预期使用它了：

interface Data {
  price: number;
  timestamp: string;
}

let old_data: string = fs.readFileSync(path, "utf8")
// ...
let json_obj: Data[] = JSON.parse(old_data) || [] // No longer need extra array; initialoze as an empty array if needed
json_obj.push(data)

Answer 2

问题出在 .json 文件中，而不是函数中。所以如果你想让你的脚本正常工作


function writeToJson(path: string, data: any, rewrite: boolean = false) 
{
    let old_data: any = fs.readFileSync(path)
    if(old_data.length == 0 || rewrite == true)
    {
        fs.writeFileSync(path, JSON.stringify(data, null, 4))
        return
    }
    let json_obj: any = [JSON.parse(old_data)] // without brackets it reverts an error
    json_obj.push(data)
    fs.writeFileSync(path, JSON.stringify(json_obj, null, 4))
}

确保您的 json 文件已经以方括号开头


[
   // empty or some data
]

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